https://www.xmswiki.com/api.php?action=feedcontributions&user=Eshaw&feedformat=atomXMS Wiki - User contributions [en]2024-03-29T13:00:19ZUser contributionsMediaWiki 1.39.0https://www.xmswiki.com/index.php?title=WMS:TIN_Interpolation&diff=28580WMS:TIN Interpolation2008-10-11T20:36:42Z<p>Eshaw: New page: ==Interpolate TIN To TIN== The '''Interpolate to TIN''' command of the '''TIN''' menu allows you to interpolate the elevations of the active TIN to one or more TINs. If more than one othe...</p>
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<div>==Interpolate TIN To TIN==<br />
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The '''Interpolate to TIN''' command of the '''TIN''' menu allows you to interpolate the elevations of the active TIN to one or more TINs. If more than one other TIN exists a dialog will appear that lets you select the TIN(s) you wish to interpolate to. No changes occur in the elevations of the active TIN.<br />
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==Interpolate TIN To 2D Grid==<br />
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The '''Interpolate to 2D Grid''' command of the '''TIN''' menu interpolates the elevations of the active TIN to the 2D Grid. Only available if both a TIN and a 2D Grid exist.<br />
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==Related Topics==<br />
* [[WMS:2D Grid Module|2D Grids]]<br />
* [[WMS:Interpolation Options|Interpolation Options]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Introduction_to_TINs&diff=28578WMS:Introduction to TINs2008-10-11T20:30:53Z<p>Eshaw: </p>
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<div>TINs are formed by connecting a set of xyz points (scattered or gridded) with edges to form a network of triangles. Points used to create TINs can be obtained by digitizing a contour map (or a scanned image inside of WMS), by generated automatically from feature arcs and polygons, or by using DEMs or existing TINs as background elevation maps. TINs can be contoured, displayed in oblique view with mapped images and hidden surfaces removed, and several other display options that can be set to visualize and understand the terrain surface better. TINs are used for basin delineation and drainage analysis. Basin areas and several other geometric parameters can be computed and combined with hydrologic analyses.<br />
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The Project Explorer can be used to set the name of the TIN by either double-clicking on the TIN name, or by right-clicking on the name and choosing Rename. The name of the TIN is always displayed along with the TIN icon when using the Select TIN tool.<br />
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==Related Topics==<br />
* [[WMS:Creating a TIN from a Scanned Image|Creating a TIN from a Scanned Image]]<br />
* [[WMS:Creating TINs|Creating TINs]]<br />
* [[WMS:Where Can I Get Data?|Data Acquisition]]<br />
* [[WMS:Merging TINs|Merging TINs]]<br />
* [[WMS:TIN Interpolation|TIN Interpolation]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:TIN_Options&diff=28577WMS:TIN Options2008-10-11T20:30:10Z<p>Eshaw: </p>
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<div>The TIN Options dialog controls setting for several of the TIN creation and editing functions.<br />
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[[Image:image72.jpg]]<br />
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==Vertex Options==<br />
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There are two different modes for creating vertices, digitizing and non-digitizing modes. In digitizing mode all of the options for triangulation of new points, confirmation of z values etc. are disabled and the z values of newly created vertices are determined by the z value entered in the z edit field of the edit window. Newly created vertices are not triangulated into a TIN so triangulation of vertices should be done once digitizing vertices is completed. [[WMS:Creating a TIN from a Scanned Image|See creating a TIN from a scanned image]] for more information on how digitizing mode can be used to create a TIN from a contour map.<br />
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In non-digitizing mode there are several options that control what happens to vertices and triangles of a TIN when new vertices are created:<br />
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*If the Retriangulate after deleting is checked, the region surrounding the vertex will be retriangulated as each vertex is deleted. Otherwise, the triangles adjacent to the vertex are simply deleted.<br />
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*If the check box entitled Adjust boundary to include exterior vertices is selected, the boundary of the TIN will be changed so that the new vertex becomes part of the TIN if a new point is added outside the active TIN. If the new vertex is in the interior of the active TIN, the vertex will be automatically incorporated into the TIN. <br />
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*If the check box entitled Confirm z values item is selected, WMS will prompt for a z value every time a new vertex is created.<br />
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*If the Interpolate for default z on interior item is checked and a new vertex is entered in the interior of a TIN, the program will linearly interpolate a default z-value from the plane equation defined by the triangle containing the point.<br />
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*The default z value edit box displays the z value that will be assigned all subsequent new vertices created with the Create Vertex tool if the Confirm z values check box is not selected.<br />
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*If the Extrapolate for default z on exterior item is checked and a new vertex is entered outside the TIN boundary, the program will extrapolate a default z-value by using a gradient based inverse distance weighted interpolation.<br />
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*The duplicate vertex tolerance edit box shows the tolerance used for such TIN operations as removing duplicate vertices, insertion of breaklines, and dividing drainage boundaries. You should not need to change this value, but occasionally it becomes the only way to work around sticky numerical problems.<br />
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*The maximum filter angle is used when thinning dense vertex lists for more reasonable management. This is particularly useful when processing TINs generated from LIDAR technology.<br />
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==Triangulation Optimization==<br />
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There are two different ways of generating an initial triangulation of the xyz vertices for a TIN.<br />
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*Angle optimization prioritizes the creation of triangles with as near equal angles as possible.<br />
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*Area optimization prioritizes the creation of triangles with as near equal areas as possible.<br />
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==Triangle Options==<br />
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The triangle options are used when searching for [[WMS:Boundary Triangles|thin boundary triangles]] to eliminate after performing an automated triangulation.<br />
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==Breakline Options==<br />
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When [[WMS:TIN Breaklines|enforcing breaklines]] with feature arcs, elevations can be linearly interpolated from the TIN, or derived from the z-values of the feature vertices (of course it is important that z-values are defined for the vertices if this option is selected).<br />
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==Related Topics==<br />
* [[WMS:Delete Duplicates|Removing Duplicates]]<br />
* [[WMS:Triangulating|Triangulating]]<br />
* [[WMS:Creating a TIN from a Scanned Image|Creating a TIN from a Scanned Image]]<br />
* [[WMS:Creating Vertices|Creating Vertices]]<br />
* [[WMS:TIN Breaklines|Breaklines]]<br />
* [[WMS:Boundary Triangles|Selecting Boundary Triangles]]<br />
* [[WMS:Triangulation Optimization|Triangulation Optimization]]<br />
* [[WMS:TIN Interpolation|TIN Interpolation]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Editing_DEMs&diff=28576WMS:Editing DEMs2008-10-11T20:25:09Z<p>Eshaw: /* Related Topics */</p>
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<div>==Trimming DEMs==<br />
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The '''Trim''' command is used to set the area of DEM that you wish to work with. A DEM by definition includes a rectangular area, but you may not need to process in the entire area to delineate a watershed, or prepare information for a hydraulic model so it is convenient to be able to trim away the parts of the DEM that are not needed. <br />
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The illustration belows indicates a rectangle that bounds the area of interest within a larger DEM model.<br />
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[[Image:WMSImageSetActiveRgn.png]]<br />
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When choosing the '''Trim''' command you can enter a polygon interactively or select an existing feature polygon in order to identify the region of interest within the DEM. If a polygon is already selected prior to choosing the '''Trim''' command then the selected polygon will be used for trimming without a prompt. When trimming with a polygon, only the DEM points within the polygon will have active elevations as everything outside the polygon, but within the bounding rectangle of the polygon is set to a NODATA value as illustrated in the figures below.<br />
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[[Image:WMSImage272.png]][[Image:WMSImage0274.png]]<br />
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==Filling Gaps Between DEMs==<br />
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When reading in [[WMS:Importing USGS DEMs|multiple DEM files that are adjacent]], a small area or gap between the DEMs may have no elevation data. The Fill command will interpolate an elevation for the selected DEM cells (or scan automatically for all such regions if a cell block is not selected) that are classified as "NODATA." The elevation for a selected NODATA cell is determined using [[WMS:Inverse Distance Weighted Interpolation|inverse distance weighted interpolation]] from its eight nearest neighbor cells (if any of the eight neighboring cells are NODATA cells then they are not used in the interpolation). This command is intended to correct single isolated DEM points or a single row/column, and is not intended to create data for large regions of NODATA cells, especially regions on the border of the DEM.<br />
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==Deleting DEMs==<br />
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The '''Delete''' command in the '''DEM''' menu will delete from memory (not the hard drive) the current DEM. A DEM may also be deleted by right-clicking in the Project Explorer and choosing the '''Delete''' command. <br />
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==Related Topics==<br />
* [[WMS:Delete NULL Basins Cell Data|Inactive NULL Basin]]<br />
* [[WMS:Trimming TINs|Trimming a TIN]]<br />
* [[WMS:Overview|Project Explorer]]<br />
* [[WMS:Deleting Data|Deleting Data]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Introduction_to_DEMs&diff=28572WMS:Introduction to DEMs2008-10-11T20:22:47Z<p>Eshaw: </p>
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<div>DEMs can be used to delineate watershed and sub-basin boundaries which can subsequently be converted to a series of arcs and polygons. DEMs can also be converted to TINs and used to develop hydraulic models. Additionally, DEMs can be contoured and displayed in oblique view. When creating a TIN, they can be used as a background elevation map.<br />
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==Related Topics==<br />
* [[WMS:Where Can I Get Data?|Data Acquisition]]<br />
* [[WMS:Delineation with DEMs|Basin Delineation with DEMs]]<br />
* [[WMS:Smoothing DEMs|Smoothing DEMs]]<br />
* [[WMS:Editing DEMs|Editing DEMs]]<br />
* [[WMS:Editing DEM Elevations|Editing DEM Elevations]]<br />
* [[WMS:Converting DEMs|Converting DEMs]]<br />
* [[WMS:Interpolation of DEMs elevations to TINs and 2D Grids|Interpolation to TINs and 2-D Grids]]<br />
* [[WMS:TOPAZ|TOPAZ]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Triangulation&diff=28571WMS:Triangulation2008-10-11T20:15:49Z<p>Eshaw: /* Related Topics */</p>
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<div>A TIN can be constructed by triangulating a set of vertices. WMS connects the vertices with a series of edges to form a network of triangles. The resulting triangulation satisfies the Delauney criterion The Delauney criterion ensures that no vertex lies within the interior of any of the circumcircles of the triangles in the network (figure shown below).<br />
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As the triangulation process proceeds, adjacent triangles are compared to see if they satisfy the Delauney criterion. If necessary, the adjacent edge of the two triangles is swapped (the diagonal of the quadrilateral defined by the two triangles is changed to the other two vertices) in order to satisfy the Delauney criterion. This edge swapping process forms the basis of the triangulation algorithm.<br />
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When a new point is inserted into a TIN, the point is incorporated into the TIN and the edges of the triangles adjacent to the new point are swapped as necessary in order to satisfy the Delauney criterion. If the Delauney criterion is satisfied everywhere on the TIN, the minimum interior angle of all of the triangles is maximized. The result is that long thin triangles are avoided as much as possible.<br />
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[[Image:image64.gif]]<br />
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It is important to note that the triangulation described above is used as a preliminary step to creating a TIN conditioned for basin delineation and is not sufficient in most cases for actually doing the drainage delineation. Even if you begin with TIN data you will want to create another [[WMS:Creating TINs|TIN using feature objects]].<br />
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==Related Topics==<br />
* [[WMS:Triangulating|Triangulating]]<br />
* [[WMS:TIN Options|TIN Options]]<br />
* [[WMS:Creating TINs|Creating TINs from Feature Objects]]<br />
* [[WMS:Triangulation Optimization|Triangulation Optimization]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Triangulating&diff=28570WMS:Triangulating2008-10-11T20:15:36Z<p>Eshaw: </p>
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<div>Vertices can be triangulated using the currently selected triangulation algorithm by selecting the '''Triangles | Triangulate''' command from the '''TIN''' menu. It is important to recognize that the [[WMS:Triangulation|Delauney triangulation]] is not necessarily the best for performing drainage delineation because it does not insure that important linear features such as streams and ridges will be honored in the TIN as triangle edges. For this reason you should always use a TIN triangulated in this fashion as a "background" elevation source for [[WMS:Creating TINs|creating a new TIN from a "conceptual" model]] of feature objects.<br />
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==Related Topics==<br />
* [[WMS:Creating TINs|Creating TINs from Feature Objects]]<br />
* [[WMS:TIN Options|TIN Options]]<br />
* [[WMS:Triangulation|Delauney Triangulation]]<br />
* [[WMS:Trimming TINs|Trimming TINs]]<br />
* [[WMS:Filter|Filtering TINs]]<br />
* [[WMS:Triangulation Optimization|Triangulation Optimization]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Triangulation_Optimization&diff=28569WMS:Triangulation Optimization2008-10-11T20:14:37Z<p>Eshaw: /* Related Topics */</p>
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<div>The '''Triangles | Optimize Triangulation''' command of the '''TIN''' menu will optimize triangulation according to the following criterion: <br />
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* If Angle optimization is selected in the TIN Options dialog, the edges of triangles will be swapped to form edges that match the Delaunay criterion. <br />
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* If Area Optimization is selected in the TIN Options dialog, the edges of neighboring triangles will be swapped if the area of one triangle is more than the bias times the area of the smaller triangle.<br />
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The criteria is specified in the TIN Options dialog.<br />
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==Related Topics==<br />
* [[WMS:TIN Options|TIN Options]]<br />
* [[WMS:Triangulating|Triangulation]]<br />
* [[WMS:Triangulation|Delauney Triangulation]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Merging_TINs&diff=28566WMS:Merging TINs2008-10-11T18:54:44Z<p>Eshaw: </p>
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<div>You can merge a selected TIN with another TIN using the '''Merge''' command in the '''TIN''' menu. This is particularly useful if you wish to merge a TIN generated from one program with a TIN derived from a background elevation source such as a DEM. <br />
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For example you may have surveyed data with a lot of detail for a part of your project (such as a roadway profile) and wish to combine that with a TIN derived from a DEM of the surrounding area.<br />
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[[Image:image31.jpg]]<br />
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[[Image:image32.jpg]]<br />
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The following dialog is used to select existing TINs for merging. The merged TINs can be completed merged (all vertices combined and retriangulated), or you can specify to have vertices in overlapping regions deleted. You can delete old TINs if you wish, or keep them.<br />
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[[Image:WMSimage74.jpg]]<br />
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The following rules are adhered to when merging a list of TINs:<br />
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* The TIN at the bottom of the list of TINs to merge has the highest priority, meaning that all of its triangle edges will be preserved while vertices that overlap from TINs higher in the list will be deleted. <br />
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* If a region being deleted from one TIN overlaps any stream vertices on the TIN being deleted, the stream will be split. The stream will be cutoff wherever it "enters" the TIN selected for merging and begin again upstream where it "exits." <br />
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* Drainage data will be lost and not transferred as part of the merged TIN. <br />
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==Related Topics==<br />
* [[WMS:Introduction to TINs|Introduction to TINs]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Creating_TINs&diff=28564WMS:Creating TINs2008-10-11T18:53:44Z<p>Eshaw: /* Related Topics */</p>
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<div>A TIN can be created from a set of feature objects in a drainage coverage using the '''Create TIN''' command in the '''Feature Objects''' menu. The density of vertices in the TIN will be proportional to the vertex spacing along arcs. The Redistribute command in the Feature Objects menu can be used to adjust vertex spacing and locally refine the TIN in important areas. Either an existing TIN or a DEM can be used as a background elevation map when interpolating z values for the vertices of the TIN. If appropriate z values have been assigned to the feature arcs then the z values from the arcs will override z values interpolated from the background elevation map for TIN vertices created from feature arcs vertices.<br />
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[[Image:image44.gif]]<br />
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For TINs requiring a lot of memory (high resolution of vertices or covering a large spatial extent), it may be advantageous to build the TIN in the absence of a background DEM. Interpolation of elevations to the TIN from the DEM afterwards can be done in a “block by block” fashion using the '''Interpolate | ...to TIN''' command found in the '''DEM''' menu of the Terrain Data module. In other words you can read in portions of the DEM and interpolate to TIN multiple times. Elevations for TIN vertices that are not within the extents of the current DEM are not interpolated. No such option exists if a TIN is used as the background elevation source.<br />
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You may wonder why if you already have TIN data, you would ever use a TIN as a background elevation set. The primary purpose of creating TINs from feature objects is to insure that stream channels and other important hydrologic features are adequately represented in the TIN as triangle edges. If you simply triangulate a set of xyz scatter points, or import a TIN from another data source, it is not likely that this condition will exist. Creating a new TIN from feature objects will insure that the TIN is optimal for performing drainage analysis because the new TIN will be built “around” the feature objects.<br />
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==Related Topics==<br />
* [[WMS:Feature Objects|Feature Objects]]<br />
* [[WMS:Creating Watershed Models|Creating Watershed Models]]<br />
* [[WMS:Feature Object Guidelines|Feature Object Guidelines]]<br />
* [[WMS:Creating Grids|Creating Grids]]<br />
* [[WMS:Converting DEMs|Converting DEMs]]<br />
* [[WMS:Fill|Fill Command]]<br />
* [[WMS:Merging TINs|Merging TINs]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Deleting_Vertices&diff=28562WMS:Deleting Vertices2008-10-11T18:51:21Z<p>Eshaw: </p>
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<div>Vertices can be deleted by selecting the vertex/vertices to be deleted and hitting the DELETE or BACKSPACE key on the keyboard or by selecting the '''Delete''' command from the '''Edit''' menu. If the [[WMS:Confirm Deletions|Confirm deletions]] option is active, you will be prompted to confirm each deletion. This is helpful in preventing accidental deletions. The [[WMS:Confirm Deletions|Confirm deletions]] flag can be toggled by selecting the Confirm Deletions item from the General tab of the '''Preferences''' dialog of the '''Edit''' menu.<br />
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==Related Topics==<br />
* [[WMS:Dynamic Tool Palette|Selecting Objects]]<br />
* [[WMS:Delete|Delete]]<br />
* [[WMS:Trimming TINs|Trimming TINs]]<br />
* [[WMS:Filter|Filtering TINs]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Trimming_TINs&diff=28559WMS:Trimming TINs2008-10-11T18:48:33Z<p>Eshaw: New page: Trimming allows you to eliminate all vertices that are outside of a selected feature polygon. You must first create the feature polygon in the Map module, then select the polygon you wish ...</p>
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<div>Trimming allows you to eliminate all vertices that are outside of a selected feature polygon. You must first create the feature polygon in the Map module, then select the polygon you wish to use prior to selecting the Trim command from the TIN menu (Terrain Data module).<br />
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==Related Topics==<br />
* [[WMS:Triangulating|Triangulating]]<br />
* [[WMS:Deleting Vertices|Deleting Vertices]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Smoothing_Pits&diff=28558WMS:Smoothing Pits2008-10-11T18:47:13Z<p>Eshaw: </p>
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<div>The '''Vertices | Smooth Pits''' command of the '''TIN''' menu adjusts the elevations of pits in order to remove them. For each pit the two next highest (elevations) of adjacent vertices are located and the elevation of the pit is set to the average of these two elevations. Flat triangles should be removed before using this command.<br />
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==Related Topics==<br />
* [[WMS:Remove Flat Triangles|Removing Flat Triangles]]<br />
* [[WMS:Filter|TIN Filtering]]<br />
* [[WMS:Displaying the Stream Profile|Displaying Stream Profile]]<br />
* [[WMS:Trimming TINs|Trimming TINs]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Fill&diff=28557WMS:Fill2008-10-11T18:44:51Z<p>Eshaw: New page: The '''Fill''' command triangulates a selected polygon and merges it with the original TIN. Vertices should be distributed according to the density of TIN vertices desired on the interior ...</p>
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<div>The '''Fill''' command triangulates a selected polygon and merges it with the original TIN. Vertices should be distributed according to the density of TIN vertices desired on the interior of the TIN. The primary purpose is to fill in an area where data is missing on a TIN, or where you wish to retriangulate to a higher density.<br />
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You must have some kind of background elevation behind the polygon (e.g. a DEM or another TIN), or the resulting vertices within the polygon will all have zero elevations.<br />
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==Related Topic==<br />
* [[WMS:Triangulating|Triangulating]]<br />
* [[WMS:Creating TINs|Creating TINs from Feature Objects]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Filter&diff=28555WMS:Filter2008-10-11T18:41:25Z<p>Eshaw: </p>
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<div>Redundant and overlapping data may exist in a scattered XYZ data sets. WMS offers the ability to filter the data and remove unnecessary data points in relatively flat areas in the '''Filter''' command from the '''TIN''' menu. The user specifies an angle. Each data point is checked to see if it is in a flat region by dotting the normals of the surrounding triangles.<br />
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[[Image:image270.gif]]<br />
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If the normals are all within the specified angle, the region is considered flat and the point is deleted.<br />
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This type of processing is very important when trying to use LIDAR data. Typical LIDAR collection results in resolutions of 1-3 meters so that good detail of flood plains and channel banks is achieved. However this leaves massive amounts of points in relatively flat areas where the increased resolution is not required (it would be like asking your surveyor to get points every 5 feet just so he doesn't miss anything, when hopefully he can be much smarter). The filtering eliminates the points where they are not needed and retains the important points. (The [[WMS:References|reference]] to Creighton Omer's paper is about a study using this technique on LIDAR data for hydraulic modeling that concludes a filter angle of 4-8 degrees can be used that will result in up to 85% data reduction without impacting hydraulic modeling results.)<br />
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==Related Topics==<br />
* [[WMS:References|References]]<br />
* [[WMS:Deleting Vertices|Deleting Vertices]]<br />
* [[WMS:Triangulating|Triangulating]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Remove_Flat_Triangles&diff=28554WMS:Remove Flat Triangles2008-10-11T18:37:43Z<p>Eshaw: </p>
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<div>The '''Triangles | Remove Flat Triangles''' command attempts to eliminate flat triangles on a TIN. A first pass is made in attempt to adjust the triangulation or slightly alter vertex elevation and a second pass is then made which inserts new vertices in flat triangles and interpolates the elevation.<br />
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===Interpolating Flat Triangles===<br />
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This method inserts new points in flat triangles and adjusts the elevation of the new points by using an interpolation technique. This method works well when there is a small number of clustered (2-10) flat triangles. However, when large regions of flat triangles exist, the TIN filtering should be used before trying to remove flat objects.<br />
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When the '''Triangles | Remove Flat Triangles''' command in the '''TIN''' menu is issued, WMS computes the differences between the elevations of the flat triangles and the elevations of the surface defined by the [[WMS:Inverse Distance Weighted Interpolation|IDW quadratic interpolation scheme]]. This technique is used because of its ability to accurately infer important terrain features such as pits, peaks, streams, and ridges. The difference between the flat surface and the interpolated surface is referred to as the "deviation" of the flat triangles. The deviation is computed at regularly spaced points on the interior of each flat triangle. The subdivision factor in the Interpolation Scheme dialog controls the level of subdivision or the number of interior points. The point in each flat triangle with the maximum deviation is assumed to represent the maximum for that triangle.<br />
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Once the deviations are determined, WMS locates the flat triangle whose deviation is the maximum. A new point is added at the xy location of the maximum deviation. The elevation of the new point is computed using the [[WMS:Inverse Distance Weighted Interpolation|IDW quadratic interpolation scheme]]. The new point is inserted into the TIN, and the TIN is adjusted locally to accommodate the new point. Many times the insertion of a new point in a flat triangle combined with the local retriangulation of the TIN results in the removal of several flat triangles. The list of flat triangles is updated, the flat triangle with the next largest deviation is found, and the process is repeated. By inserting new points in this fashion, the minimum number of new points will be added in the best possible locations to infer local minima and maxima such as pits, peaks, streams, and ridges.<br />
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Once all flat triangles have been eliminated, further processing to remove flat edges and pits is done. Prior to performing the '''Triangles | Remove Flat Triangles''' command all [[WMS:Locked/Unlocked Vertices|TIN vertices are locked]]. Any new vertices created as part of this process are set to ulocked status. When completed you will be able to distinguish the new vertices from the original by observing the ones that are unlocked. You may wish to unlock all vertices for further editing.<br />
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==Related Topics==<br />
* [[WMS:Smoothing Pits|Smooth Pits]]<br />
* [[WMS:Locked/Unlocked Vertices|Locked/Unlocked Vertices]]<br />
* [[WMS:Interpolation Options|Interpolation Options]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Creating_Vertices&diff=28552WMS:Creating Vertices2008-10-11T18:34:20Z<p>Eshaw: </p>
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<div>New vertices can be created by selecting the Create Vertices tool from the Tool Palette and clicking in the Graphics Window where the new vertex is to be located. The x and y values of the vertex are determined by the position of the mouse cursor when a click is made. The z value must be entered separately. A default z value and other parameters governing the creation of new vertices can be set by selecting the '''TIN Options''' command from the '''TIN''' menu.<br />
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==Related Topics==<br />
* [[WMS:Creating a TIN from a Scanned Image|Creating a TIN from a Scanned Image]]<br />
* [[WMS:Editing XYZ Coordinates|Editing XYZ Coordinates]]<br />
* [[WMS:TIN Options|TIN Options]]<br />
* [[WMS:Deleting Vertices|Deleting Vertices]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Drainage_Data_to_Feature_Objects&diff=28549WMS:Drainage Data to Feature Objects2008-10-11T18:25:36Z<p>Eshaw: </p>
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<div>In order to provide a way to export watersheds delineated from TIN data sources to GIS they must first be converted to [[WMS:Feature Objects|feature objects]]. This can be done using the '''Drainage Data -> Feature Objects''' command. When performing this operation the TIN is deleted and the drainage boundary and stream network are converted to feature polygons and feature arcs. The '''Export''' command from the '''File''' menu can then be used to save the feature objects to a shapefile so that the information can easily be transferred to a GIS. All of the drainage data computed/entered for the TIN basins and junctions (areas, lag times, slopes, and other hydrologic modeling parameters) are automatically transferred during the conversion process.<br />
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==Related Topics:==<br />
* [[WMS:TIN Boundary to Polygon|TIN Boundary to Polygon]]<br />
* [[WMS:TIN to DEM|TIN to DEM]]<br />
* [[WMS:TIN to Scatter Points|TIN to Scatter Points]]<br />
* [[WMS:TIN Contours to Feature Objects|TIN Contours to Feature Objects]]<br />
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{{WMSMain}}<br />
[[Category:TINs]]</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Converting_DEMs&diff=28548WMS:Converting DEMs2008-10-11T18:23:43Z<p>Eshaw: /* Related Topics */</p>
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<div>==Converting DEMs to TINs==<br />
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===All DEM Points===<br />
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Using the '''Conversion | DEM->TIN''' command from the '''DEM''' menu, you can convert all of your DEM cell points to TIN vertices and triangulate. In general it is not efficient to do this, but it may be desirable to create the TIN for use in extracting cross sections for a hydraulic model, or other purposes where a TIN is required. More efficient ways of converting DEMs to a TIN include using a [[WMS:Creating TINs|bounding polygon]] and interior breakline arcs (i.e. streams and/or ridges), or filtering out less important elevation points using the '''Filtered DEM Points''' command.<br />
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===Filtered DEM Points===<br />
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An alternative to converting every DEM elevation to a TIN vertex (especially for very large DEMs) is to filter out DEM points where the curvature in the terrain between elevation points is small (i.e. a relatively constant slope). The filter algorithm is based on [[WMS:References|Southard (1990)]] where a second difference (difference of differences) is computed for each of the eight neighbors (adjusted appropriately for DEM points on the boundary or corners). This second difference is the second derivative of elevation or curvature (the first difference is slope) and represents large changes in slope. <br />
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A filter rank is then specified to determine the sensitivity. By default the filter rank is 5 which means a point will be kept if 5 or more of the 8 neighbors have a lower curvature. The maximum value for the rank is 8, meaning the point is only kept if all 8 neighbors have lower curvature, and the minimum is 0, meaning all points will be kept. By adjusting based on a rank and not just the magnitude of curvature, points in flatter areas where curvature may be small, but is changing rapidly relative to the points around it.<br />
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[[Image:WMSImage80.png]]<br />
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==DEM Contours to Feature Objects==<br />
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The DEM Contours to Feature Objects command ('''Conversion - DEM Contours->Feature'''... command from the '''DEM''' menu) converts the current linear contours from the DEM to a series of Feature Arcs which could then be exported as a shapefile. Feature arcs carry an elevation attribute and the elevation of the contour is stored in this attribute. When exporting the arcs as a shapefile the elevation attribute field will be saved automatically.<br />
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==Related Topics==<br />
* [[WMS:Creating TINs|Creating TINs from Feature Objects]]<br />
* [[WMS:References|References]]<br />
* [[WMS:Save As|Saving a Shape File]]<br />
* [[WMS:TIN Contours to Feature Objects|TIN Contours to Feature Objects]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:TIN_to_DEM&diff=28545WMS:TIN to DEM2008-10-11T17:59:30Z<p>Eshaw: </p>
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<div>A DEM may be created from any TIN using the '''Convert | TIN->DEM''' command in the '''TIN''' menu. A resolution (x and y spacing) must be defined and then an interpolation method specified (linear is the default) to interpolate DEM elevations from the TIN. Since a DEM must be rectangular, elevations that are outside of the TIN boundary are given a NODATA value of -9999.<br />
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==Related Topics==<br />
* [[WMS:TIN to Scatter Points|TIN to Scatter Points]]<br />
* [[WMS:Interpolation Options|Interpolation Options]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Interpolation_Options_for_Floodplain_Delineation&diff=28544WMS:Interpolation Options for Floodplain Delineation2008-10-11T17:26:50Z<p>Eshaw: New page: Since stages are defined by a 2D scatter set, the same interpolation options are used for flood plain delineation as are used in the 2D Scatter module. ==Re...</p>
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<div>Since stages are defined by a 2D scatter set, the same [[WMS:Interpolation Options|interpolation options]] are used for flood plain delineation as are used in the 2D Scatter module.<br />
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==Related Topics==<br />
* [[WMS:Interpolation Options|Interpolation Options for Scatter Data Sets]]<br />
* [[WMS:Overview of Flood Plain Delineation|Floodplain Delineation]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Overview_of_Floodplain_Delineation&diff=28543WMS:Overview of Floodplain Delineation2008-10-11T17:23:59Z<p>Eshaw: /* Related Topics */</p>
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<div>In addition to stream network and drainage basin delineation, WMS can also be used to perform floodplain delineation. Water levels simulated by a river hydraulic model or collected from different sources are read from a text file as a scatter data set (see [[WMS:Preparing Stage Data|preparing stage data]] for more help). A smooth water surface is constructed by interpolating water levels at TIN vertices. User specified [[WMS:Flood Barrier|flood barriers]] such as embankments, roads, etc are also considered during this process. This surface is then intersected with the triangles in TIN representing the ground elevations, and the resulting set of edges defines the floodplain.<br />
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The basic steps to performing a flood plain delineation in WMS include:<br />
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:*[[WMS:Introduction to TINs|Prepare a triangulated irregular network]] (TIN) surface of the area where the delineation is to be performed. This can be done by reading scattered elevation, converting from a DEM, or digitizing a contour map.<br />
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[[Image:image430.gif]]<br />
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:*[[WMS:Preparing Stage Data|Prepare your water surface elevation data]]. Water elevations data consists of a series of surface water elevations points defined as x, y, z (where z is the elevation of the water surface). Such points could be the results of a hydraulic model simulation, calculated in the WMS channel calculator, or retrieved from a known gaging station. They are stored as a [[WMS:Scatter Point Sets|scatter data set]].<br />
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[[Image:image431.gif]]<br />
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:*Select the appropriate [[WMS:Delineate Flood Plain|options for delineating]] the flood plain, including the possibility of using a barrier coverage, and then delineate the flood.<br />
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[[Image:image432.gif]]<br />
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:*The result of the flood plain delineation will be a new dataset of water surface elevations and/or inundation depths. These datasets can be used to display contours on the TIN and converted to a series of output coverages (maps), including a [[WMS:Flood Depth Map|flood depth map]] and [[WMS:Flood Impact Map|impact maps]] derived from two separate delineations.<br />
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===Stochastic Modeling===<br />
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The flood plain delineation tools are [[WMS:Stochastic Modeling|connected]] with the HEC-1 hydrologic model and HEC-RAS hydraulic model to perform a series of floodplains based on the results of a series of model runs where rainfall, CN, and Manning's n are varied stochastically within a range of valid results.<br />
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==Related Topics==<br />
* [[WMS:Differences From Earlier Versions (Version 6.0 and earlier)|Differences From Earlier Versions]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS:Preparing Stage Data|Preparing Stage Data]]<br />
* [[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
* [[WMS:Hydraulic Modeling Introduction|Hydraulic Modeling]]<br />
* [[WMS:Interpolation Options for Floodplain Delineation|Interpolation Options for Floodplain Delineation]]<br />
* [[WMS:SMPDBK|Simplified Dam-Break Analysis]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Create_Flood_Barrier_Coverage&diff=28541WMS:Create Flood Barrier Coverage2008-10-11T17:11:51Z<p>Eshaw: New page: This option allows you to incorporate flood barriers through a coverage representing natural or artificial barriers that are not represented explicitly in the elevations of a TIN. [[WMS:De...</p>
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<div>This option allows you to incorporate flood barriers through a coverage representing natural or artificial barriers that are not represented explicitly in the elevations of a TIN. [[WMS:Delineate Flood Plain|The floodplain delineation process considers these barriers during water level interpolation]]. The resulting flood depth will be closer to reality, rather than a mere interpolation. For example, an embankment or a road is not always represented in a DTM. In order to delineate a floodplain properly, these barriers must be considered in a hydraulic model as well as in the floodplain delineation process. This option not only incorporates such existing barriers in the process, it also provides the flexibility so that they can be considered proposed structures and evaluate the “what if” scenarios.<br />
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Note: This is not equivalent to actually running a hydraulic model with the "proposed" embankment or structure, but will limit the flood plain delineation from proceeding beyond, or at least force calculated flow paths to go around.<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS:Flow Paths and Barrier Coverages|Flow Paths and Barrier Coverages]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Flood_Barrier&diff=28540WMS:Flood Barrier2008-10-11T17:07:48Z<p>Eshaw: </p>
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<div>A flood barrier coverage represents natural or artificial barriers that are not represented explicitly in the elevations of a TIN. The [[WMS:Overview of Flood Plain Delineation|flood plain delineation process]] can then use these barriers while interpolating water surface elevations across a TIN surface. The resultant flood depth will be closer to reality rather than a mere interpolation. For example, an embankment or a road is not always represented in a TIN.<br />
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==Related Topics==<br />
* [[WMS:Coverages|Coverages]]<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Flow Paths and Barrier Coverages|Flow Paths and Barrier Coverages]]<br />
* [[WMS:Create Flood Barrier Coverage|Create Flood Barrier Coverage]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Flow_Paths_and_Barrier_Coverages&diff=28539WMS:Flow Paths and Barrier Coverages2008-10-11T17:07:21Z<p>Eshaw: /* Related Topics */</p>
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<div>Figure (a) shows natural high ground and embankment in a TIN and the location of water levels and flood barriers used in the floodplain delineation. This and the subsequent figures demonstrate the following options: 1) floodplain delineation without considering the flow path option, 2) floodplain delineation considering the flow path option, and 3) floodplain delineation considering flood barriers.<br />
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[[Image:image425.gif]]<br />
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(a) Sample TIN for illustrating flood plain delineation options.<br />
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The flow path option in the [[WMS:Delineate Flood Plain|floodplain delineation process]] ensures that the sources of water (i.e. the water levels) and the areas flooded are hydraulically connected. This is an important option because if not applied, the process may interpolate water levels while ignoring obstructions between the water levels and the point of interpolation. The effect of such interpolation is shown in Figure (b) where the floodplain is delineated without considering flow paths. The figure shows two flooded areas separated from each other by a natural embankment. Considering the water levels, which are located outside the embankment and lower than the elevation of the embankment, the area inside the embankment should not be flooded. Therefore, it is obvious that the flooding inside the embankment is the effect of the interpolation done by the process without checking hydraulic connectivity.<br />
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[[Image:image426.gif]]<br />
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(b) Flood plain delineation without consideration of flow paths<br />
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The more realistic flooding scenario is simulated when flow paths are considered as shown in Figure (c). In this case the process first checks for hydraulic connectivity before performing any interpolation at any location inside the embankment. Since the water is obstructed by the embankment the process does not find any flow paths. As a result the area inside the embankment remains flood free.<br />
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[[Image:image427.gif]]<br />
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(c) Flood plain delineation using flow paths.<br />
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Not all natural and artificial flood obstructions are well represented by digital terrain models. The effect of these obstructions cannot be simulated with the flow path option alone. The use of flood barrier coverages along with the flow path option provides a way to address this issue in the floodplain delineation process. The effect of using flood barriers in the floodplain delineation is demonstrated in Figure (d), which shows an area on each side of the river that is protected by a floodwall. Since the elevations in the TIN do not show the presence of the floodwalls, a flood barrier coverage is used to simulate the effect in the floodplain delineation. While checking hydraulic connectivity, the process recognizes those barriers and therefore, reports the areas inside the barrier as flood free.<br />
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[[Image:image428.gif]]<br />
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(d) Flood plain delineation using a flood barrier coverage.<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS:Search Radius and Flow Distance|Search Radius and Flow Distance]]<br />
* [[WMS:Create Flood Barrier Coverage|Create Flood Barrier Coverage]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Stochastic_Modeling&diff=28538WMS:Stochastic Modeling2008-10-11T16:27:06Z<p>Eshaw: </p>
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<div>There is always a great deal of uncertainty in hydrologic and hydraulic modeling and the parameters that are used to develop solutions. Despite this, a typical flood plain boundary is black and white in that you are either in or out of the flood plain. A good engineer might be able to dispute a flood plain boundary by performing a hydrologic/hydraulic analysis with a set of equally probable parameters that results in a difference in the flood plain delineation. Until recently, computer programs lacked the ability to consider multiple probable answers and report a probabilistic floodplain boundary, but with the Stochastic Modeling tools in WMS this is possible using a combination of HEC-1 for hydrologic analysis, HEC-RAS for 1D hydraulic river modeling, and the WMS flood plain delineation tools.<br />
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You can "connect" the results of HEC-1 to a developed HEC-RAS model and then run them as many times consecutively, with the results of the HEC-1 analysis feeding the boundary conditions for an HEC-RAS model. Certain parameters (at this point only basin CN and precipitation within HEC-1, and Manning's roughness within HEC-RAS) can be varied within a range of reasonable values using Monte Carlo or Latin Hypercube simulations in order to create a number of simulations. The results of each HEC-RAS model can then be used to delineate a series of flood plains. The combination of all floodplains can then be examined in order to derive a "probabilistic" flood plain where a region flooded by 100% of the model simulation combinations can be distinguished from an area that is flooded by only 50% of the models as shown in the figure below:<br />
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[[Image:image277.gif]]<br />
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The following steps outline the process for developing a stochastic model of floodplain boundaries using WMS, HEC-1, and HEC-RAS.<br />
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:1.[[WMS:Hydrologic Model|Develop a hydrologic model with HEC-1]]<br />
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[[Image:image310.gif]]<br />
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:2.[[WMS:Hydrologic Model|Develop a working model in HEC-RAS]]<br />
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[[Image:image311.gif]]<br />
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:3.[[WMS:Flood Plain Delineation|Establish appropriate flood plain delineation parameters for your area]]<br />
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:4.[[WMS:Stochastic Simulation Parameters|Set up stochastic simulation parameters]]<br />
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:5.[[WMS:Linking Models|Assign boundary conditions between models and run the stochastic simulation]]<br />
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:6.[[WMS:Stochastic-Running a Simulation|Run the simulation]]<br />
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:7.[[WMS:Post Processing|Post Process the results]]<br />
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[[Image:image313.gif]]<br />
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[[Image:image312.gif]]<br />
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==''Related Topics''==<br />
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[[WMS:HEC-1 Run Analysis|HEC-1 Modeling]]<br />
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[[WMS:Hydraulic Modeling Introduction|HEC-RAS Modeling]]<br />
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[[WMS:Overview of Flood Plain Delineation|Flood Plain Delineation]]</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Hydrologic_Model&diff=28537WMS:Hydrologic Model2008-10-11T16:25:26Z<p>Eshaw: </p>
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<div>The HEC-1 Interface tools in WMS can be used to develop a working HEC-1 model. It is important that this model be running effectively (i.e. calibrated and/or adjusted to give credible results) prior to using it for the Stochastic Modeling simulation.<br />
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[[Image:image85.jpg]]<br />
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The only parameters at this point that can be varied within a range of probable answers are rainfall and CN (curve number for the different basins. This is done by setting the [[WMS:HEC-1 Precipitation|precipitation]] or [[WMS:HEC-1 SCS Loss Method (LS)|CN]] to be a negative number in their respective dialogs. This negative number is a key number and should be unique for each stochastic variable you create. When running the stochastic simulation WMS will substitute the simulation specific parameter for the defined key. You can then setup a stochastic variable for HEC-1 in the Stochastic Run Parameters dialog. A key value (matching the key you defined in the materials property) starting value, min value, max value, standard deviation and distribution type.<br />
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[[WMS:Hydraulic Model|Next Step in Stochastic Modeling]]<br />
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==Related Topics==<br />
*[[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
*[[WMS:HEC-1 Parameters|HEC-1 Modeling]]<br />
*[[WMS:HEC-1 Precipitation|Precipitation Data]]<br />
*[[WMS:HEC-1 SCS Loss Method (LS)|Curve Number]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Hydraulic_Model&diff=28536WMS:Hydraulic Model2008-10-11T16:24:44Z<p>Eshaw: </p>
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<div>The [[WMS:Hydraulic Modeling Introduction|HEC-RAS interface]] tools in WMS can be used to developing a working HEC-RAS model. It is important that this model be running effectively (i.e. calibrated and/or adjusted to give credible results) prior to using it for the Stochastic Modeling simulation.<br />
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[[Image:image279.gif]]<br />
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The only parameter at this point that can be varied within a range of probable answers are Manning's coefficients for the different material types. This is done by setting the roughness to be a negative number in the [[WMS:Material Properties|HEC-RAS Materials]] dialog. This negative number is a key number and should be unique for each stochastic variable you create. When running the stochastic simulation WMS will substitute the simulation specific parameter for the defined key. You can then setup a stochastic variable for HEC-RAS in the Stochastic Run Parameters dialog. A key value (matching the key you defined in the materials property) starting value, minimum value, maximum value, standard deviation and distribution type.<br />
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[[Image:image84.jpg]]<br />
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[[WMS:Hydrologic Model|Previous Step in Stochastic Modeling]]<br />
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[[WMS:Flood Plain Delineation|Next Step in Stochastic Modeling]]<br />
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==Related Topics==<br />
*[[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
*[[WMS:Overview of Flood Plain Delineation|HEC-RAS Modeling]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Floodplain_Delineation&diff=28535WMS:Floodplain Delineation2008-10-11T16:23:49Z<p>Eshaw: </p>
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<div>The floodplain delineation portion of the stochastic modeling uses the results from each HEC-RAS model to develop a floodplain for each run. The [[WMS:Overview of Flood Plain Delineation|floodplain delineation]] is the same model used by WMS to perform individual floodplain delineations.<br />
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[[Image:image86.jpg]]<br />
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The only parameters at this point that can be varied within a range of probable answers the [[WMS:Search Radius and Flow Distance|search radius]] of the flood plain delineation. This is done by setting the search radius in the Floodplain Delineation Options be a negative number. This negative number is a key number and should be unique for each stochastic variable you create. When running the stochastic simulation WMS will substitute the simulation specific parameter for the defined key. You can then setup a stochastic variable for Floodplain in the Stochastic Run Parameters dialog. A key value (matching the key you defined in the materials property) starting value, min value, max value, standard deviation and distribution type.<br />
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[[WMS:Hydraulic Model|Previous Step in Stochastic Modeling]]<br />
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[[WMS:Stochastic Simulation Parameters|Next Step in Stochastic Modeling]]<br />
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==Related Topics==<br />
*[[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
*[[WMS:Overview_of_Flood_Plain_Delineation|Floodplain Delineation]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Stochastic_Simulation_Parameters&diff=28534WMS:Stochastic Simulation Parameters2008-10-11T16:05:24Z<p>Eshaw: </p>
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<div>There are several simulation parameters that control a stochastic simulation. They are defined in the Stochastic Run Parameters dialog shown below. Each section of this dialog is discussed below.<br />
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[[Image:image87.jpg]]<br />
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Simulation Type<br />
The simulation type and number of simulations can be set. In a Monte Carlo simulation, each specified input variable is randomly varied within a specified minimum and maximum value a given number of times. If only a few simulations are run it may not be guaranteed to fully explore the parameter space. A Latin Hypercube simulation, on the other hand, divides the range into intervals and insures that parameters are chosen from each interval. With this kind of simulation you are more likely to explore the parameter space with fewer simulations.<br />
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Stochastic Models<br />
HEC-1 or TR-20 for hydrologic modeling, HEC-RAS for hydraulic modeling, and Floodplain Delineation are the only currently available models for stochastic modeling. For each model you include a basin input file and solution files directory needs to be defined. For HEC-1, TR-20, or HEC-RAS you should select the input file of the already created model. These models will have key values (negative numbers) for the input parameters that will be defined as stochastic variables. The current floodplain delineation options will be saved in the flood run file.<br />
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You can add stochastic variables for any of the models. Each stochastic variable requires a key value (a negative number that has been entered in place of a parameter such as precipitation), a type, a starting value, a minimum value, a maximum value, a standard deviation, and a distribution. The distribution can be either normal or uniform and optionally defined as log.<br />
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[[WMS:Flood Plain Delineation|Previous Step in Stochastic Modeling]]<br />
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[[WMS:Linking Models|Next Step in Stochastic Modeling]]<br />
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==Related Topics==<br />
*[[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
*[[WMS:Hydrologic Modeling Module|Hydrologic Modeling]]<br />
*[[WMS:Hydrologic Modeling Module|Hydraulic Modeling]]<br />
*[[WMS:Overview_of_Flood_Plain_Delineation|Floodplain Delineation]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Linking_Models&diff=28533WMS:Linking Models2008-10-11T16:04:40Z<p>Eshaw: </p>
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<div>The final step before running a stochastic simulation is to link any required models. In particular you have to link how the hydrologic modeling results are used as boundary conditions for the HEC-RAS hydraulic model. When you choose the Run Stochastic Model option the Model Steering Dialog appears. For the hydrologic model you are using (HEC-1) you must assign the appropriate hydrograph (basin or outlet) to the river reach and section in the hydraulic model.<br />
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The option to Assign Hydrographs Automatically can be used providing a drainage coverage and centerline coverage are being used to set up the hydrologic and hydraulic models.<br />
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[[Image:image144.jpg]]<br />
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After identifying the hydrograph and the river, reach, and cross section station select the Assign Hydrograph BC button to link the models for this point. Continue until all of the appropriate model locations are linked.<br />
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When selecting OK your model simulation will run.<br />
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[[WMS:Stochastic Simulation Parameters|Previous Step in Stochastic Modeling]]<br />
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[[WMS:Stochastic-Running a Simulation|Next Step in Stochastic Modeling]]<br />
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==Related Topics==<br />
*[[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Stochastic-Running_a_Simulation&diff=28531WMS:Stochastic-Running a Simulation2008-10-11T16:03:12Z<p>Eshaw: </p>
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<div>Once the simulation begins running you will see the parameters selected for each model run, as well as the status of each run. The Read solution on exit toggle is on by default and will cause that all model solutions (hydrographs, water surface elevations, and floodplain delineations) are read when the simulations are completed.<br />
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[[Image:image83.jpg]]<br />
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[[WMS:Linking Models|Previous Step in Stochastic Modeling]]<br />
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[[WMS:Post Processing|Next Step in Stochastic Modeling]]<br />
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==Related Topics==<br />
*[[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Post_Processing&diff=28530WMS:Post Processing2008-10-11T15:59:42Z<p>Eshaw: /* Annual Exceedance Probability (AEP) Map */</p>
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<div>After finishing a stochastic simulation there are two primary results read back into WMS for each simulation: hydrographs from the HEC-1 model, and the floodplain depths and water surface elevations for each run.<br />
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===Hydrographs===<br />
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A series of hydrographs are loaded for each hydrograph station and can be viewed in the normal way hydrographs are viewed.<br />
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[[Image:image91.jpg]]<br />
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===Floodplains===<br />
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Each floodplain delineation results in a water surface elevation and a flood depth data set. Each pair of data sets are organized in a folder underneath the TIN in the Project Explorer. You can set the contour options for a TIN and select the data set you wish to be active and displayed from the Project Explorer.<br />
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[[Image:image330.gif]]<br />
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[[Image:image137.jpg]]<br />
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===Probabilistic Floodplain Boundary===<br />
A final data set showing the probability of flooding is also created from all of the individual floodplain data sets. The probabilistic flood plain indicates for each vertex on the TIN the percentage of model runs that resulting in inundation at the point.<br />
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[[Image:image135.jpg]]<br />
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Close up view<br />
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[[Image:image136.jpg]]<br />
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===Annual Exceedance Probability (AEP) Map===<br />
When using the stochastic hydrologic/hydraulic/floodplain delineation tools it is possible to generate an annual exceedance probability map. This is done by generating inundation maps that consider the range of all possible floods for all return periods. The result is a map that identifies the annual exceedance probability of flooding for every TIN vertex. For example if a point is flooded 10 times in 1000 simulations then it would represent the .01 probability. The [[WMS:Return Period to Feature Objects|Return Period -> Feature Objects...]] command allows you to generate contours from the AEP map for specified return periods.<br />
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[[Image:AEPMAP.jpg]]<br />
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[[WMS:Stochastic-Running a Simulation|Previous Step in Stochastic Modeling]]<br />
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==Related Topics==<br />
*[[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
*[[WMS:Displaying Hydrographs|Displaying Hydrographs]]<br />
*[[WMS:Return Period to Feature Objects|Return Period to Feature Object]]<br />
*[[WMS:Plot Windows|Plot Windows]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Return_Period_to_Feature_Objects&diff=28529WMS:Return Period to Feature Objects2008-10-11T15:53:07Z<p>Eshaw: </p>
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<div>When using the stochastic hydrologic/hydraulic/floodplain delineation tools it is possible to generate an annual exceedance probability map. This is done by generating inundation maps that consider the range of all possible floods for all return periods. The result is a map that identifies the annual exceedance probability of flooding for every TIN vertex. For example if a point is flooded 10 times in 1000 simulations then it would represent the .01 probability. The '''Return Period -> Feature Objects''' command allows you to generate contours from the AEP map for specified return periods. You should remember that such a map does not represent a solution from a single set of input parameters, but is rather the composite of several hundred or thousand simulations. <br />
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[[Image:WMSAEPMAP.jpg]]<br />
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==Related Topics==<br />
* [[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Flood_Depth_Map&diff=28528WMS:Flood Depth Map2008-10-11T15:46:28Z<p>Eshaw: /* Related Topics */</p>
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<div>The classified flood depth coverage ('''Conversion | Flood->Depth Map''' command in the '''Flood menu''') shows the variation of flood using different classes. Each class represents a range of flood depths (or water surface elevations) specified by the user. On the other hand the flood extent coverage contains the land-water boundary showing the extent of a floodplain. These coverages can be exported from WMS for reporting or use with Geographic Information Systems (GIS) to perform other flood management tasks.<br />
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The Flood Depth Coverage dialog shown below allows you to specify the options for creating your depth map.<br />
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[[Image:image268.jpg]]<br />
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You must first select the TIN (if more than one TIN is present) and the data set you wish to create the coverage for (this would typically be a water surface or flood depth data set computed from the flood delineation process, but you will note that the elevation data set may be used as well). The first range will be from 0.0 to the value specified and the second range from the values between 1 and 2. The attribute field can be used to store a keyword or text that will be exported as an attribute of a shape file when exported and should be something that uniquely identifies the given range.<br />
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An example of a flood depth map is shown below:<br />
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[[Image:image423.gif]]<br />
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''Delineated flood plain with depth contours shown.''<br />
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[[Image:image424.gif]]<br />
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''Classified Flood Depth Map exported as a shapefile to ArcView GIS.''<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS:Flood Extent Map|Create Flood Extent Map]]<br />
* [[WMS:Flood Impact Map|Create Impact Map]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Flood_Extent_Map&diff=28527WMS:Flood Extent Map2008-10-11T15:45:48Z<p>Eshaw: </p>
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<div>The '''Conversion | Flood->Extent Coverage''' command in the '''Flood''' menu allows you to create a polygon in a flood extent coverage that defines the inundated area as determined in the flood depth data set. The default inundation limit is 0.0, but you can specify any positive depth value as the inundation limit and WMS will generate a polygon that conforms to that limit.<br />
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To create the flood extent map you must specify the flood depth and water surface elevation data sets along with the inundation limit. You can optionally have WMS force or stamp in the flood extent coverage to the TIN. This will insure that you have TIN vertices with depth values at exactly 0.0. This is not the case in the original data sets computed by the flood plain delineation algorithm. The 0.0 (or any other depth contour value) value is likely interpolated along a triangle edge between two vertices. Stamping the flood extent coverage into the TIN is particularly useful for confining the display of water surface elevation values to be within the flood extent region. While the inundation limit for flood depth is a constant value (0.0), the value of water surface elevation at the inundation limit is not. By stamping in the flood extent coverage and updating the associated data sets water surface elevation contours can be controlled since WMS will set vertices outside of the flood extent coverage to be inactive and those inside to be active.<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS:Flood Depth Map|Create Flood Depth Map]]<br />
* [[WMS:Flood Impact Map|Create Impact Map]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Flood_Impact_Map&diff=28526WMS:Flood Impact Map2008-10-11T15:43:51Z<p>Eshaw: </p>
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<div>The floodplain delineation tools allow you to compare two different flooding scenarios and generate a flood impact coverage. A flood impact coverage shows increase and decrease in flooding from two different delineations using different classifications. Like other coverages, this can also be exported from WMS for reporting or other flood management purposes.<br />
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An impact map is created ('''Conversion | Flood->Impact Map''' command in the '''Flood''' menu) by showing classified increases and decreases between two separate delineations. You can specify what the increments in change are for increased and decreased (up to 5 each) flooding between two calculated datasets. A coverage of polygons is then generated for each classification. A keyword or text string can be stored with each polygon classification in order to better identify it when exported to a shape file for use in Geographic Information Systems (GIS) analysis.<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS:Flood Extent Map|Create Flood Extent Map]]<br />
* [[WMS:Flood Depth Map|Create Flood Depth Map]]<br />
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<br />
{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Differences_From_Earlier_Versions_(Version_6.0_and_earlier)&diff=28525WMS:Differences From Earlier Versions (Version 6.0 and earlier)2008-10-11T15:42:38Z<p>Eshaw: /* Related Topics */</p>
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<div>The new method differs from the previous method in several aspects. The locations of water levels and their section criteria for interpolation are more flexible than the previous method. Ability to incorporate user defined flood barriers as coverage provides an excellent opportunity to overcome the limitations inherent in digital terrain models. It also becomes useful in evaluating “what if” or post project scenarios. The new method provides several options to present flood depth data that are not available in the older method. In addition to conceptual and computational differences between two methods, you will also notice following changes while using the new method:<br />
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*[[WMS:Read Stage File|Water levels are read as a scatter data set]] as opposed to flood stages at TIN vertices.<br />
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*The method does not require “streams” in the TIN.<br />
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*Multiple events or water level time series can be read as oppose to a single event. User can choose an event while delineating floodplain. <br />
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*User can specify [[WMS:Flow Paths and Barrier Coverages|flood barriers as features in the flood barrier coverage]] and the new method incorporates those features during flood depth computation. <br />
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*Computed flood depths are stored as TIN data set and saved along with the TIN. <br />
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*Multiple flood depth data sets can be created in a TIN from multiple events.<br />
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*In addition to displaying flood depth as contours, this method can also create flood extent and [[WMS:Flood Depth Map|classified flood depth coverage]]. <br />
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*It is now possible to compare two different flooding scenarios by creating a [[WMS:Flood Impact Map|flood impact coverage]].<br />
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*Finally flood extent, classified flood depth, and flood impact coverages can be exported as shapefiles for reporting or other flood management purposes.<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Search_Radius_and_Flow_Distance&diff=28523WMS:Search Radius and Flow Distance2008-10-11T15:38:38Z<p>Eshaw: </p>
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<div>The floodplain delineation process offers several options for selecting water levels that are used in the interpolation. As expected, these options and the values of the parameters used in the process affect the resulting floodplain delineation. Therefore, care must be taken in selecting these options and appropriate values. <br />
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The effect of search radius and flow distance are demonstrated in the figure shown below. The figure shows the flooded areas delineated using a 2,000 foot search radius and flow distance in the shades of colors. The line represents the extent of flooding delineated using a 3,000 foot search radius and flow distance. For most places along the river these two flood extents coincide except in the west side of the middle portion. In that area a 3,000 foot search radius and flow distance resulted in more flooding than the 2,000 foot search radius and flow distance. This indicates the earlier the process could not compute flooding in that area because of the 2,000 foot limit. The water levels that could flood that area were discarded because they were outside of the 2,000 foot search radius or flow distance. To avoid this kind of problem, floodplains should be delineated by increasing the search radius and the flow distance until the flood extents stop changing. The final extent would then be the extent determined by the topography not by the search radius and flow distance.<br />
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[[Image:image429.gif]]<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS:Flow Paths and Barrier Coverages|Flow Paths and Barrier Coverages]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Delineate_Floodplain&diff=28522WMS:Delineate Floodplain2008-10-11T15:37:09Z<p>Eshaw: /* Select the Stage Scatter and Data Set */</p>
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<div>There are several options that must be defined in the Floodplain Delineation dialog shown in order to delineate a flood plain in WMS. Each of these options are explained and described in detail below. <br />
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[[Image:image82.jpg]]<br />
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==Select a TIN==<br />
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Most of the time you will be working with a single TIN and therefore this option will be dimmed out. However, it is possible to have more than one TIN in WMS and in such cases you will need to specify the TIN on which the flood plain delineation will be performed.<br />
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==Select the Stage Scatter and Data Set==<br />
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Water surface elevation data used to derive the floodplain are imported and processed in WMS as scatter data sets. In addition to the scatter set (the xy locations of water surface elevation points), a particular data set must also be specified. It is possible to have a single scatter set (locations of water elevations) with multiple data sets representing the water levels themselves. This will often occur when multiple scenarios of a hydraulic model are run. See the information on [[WMS:Preparing Stage Data|preparing stage files]] for more information about creating scatter data sets for floodplain delineation.<br />
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==Select a Flood Barrier Coverage==<br />
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A flood barrier coverage allows you to incorporate flood barriers representing natural or artificial barriers that are not represented explicitly by elevations in a TIN. The floodplain delineation process considers these barriers during water level interpolation. The resulting flood depth become closer to reality rather than a mere interpolation. For example, an embankment or a road is not always represented in a TIN. <br />
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In order to delineate the floodplain properly, these barriers must be considered in a hydraulic model as well as in floodplain delineation process. This option not only incorporates such existing barriers in the process, it also provides the flexibility to professionals so that they can consider proposed structures and evaluate the “what if” scenarios.<br />
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==Maximum Search Radius==<br />
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Water surface elevations are determined for each TIN vertex by using interpolation from a set of "nearest" water surface elevations in the stage scattered data set. The [[WMS:Search Radius and Flow Distance|maximum search radius]] defines the limiting distance that will be used when collecting the nearest stage scatter points. If the Use Flow Paths option is turned on then the "radius" distance is the flow distance path, whereas if the option is turned off it is the straight line (as the crow flies) distance.<br />
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==Using Flow Paths==<br />
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The flow path option in the floodplain delineation process ensures that the sources of water, i.e. the water levels, and the areas flooded (TIN vertices for which water surface elevation is interpolated) are hydraulically connected. This is an important option because if not applied, the process may interpolate water levels while ignoring obstructions between the water levels and the point of interpolation.<br />
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==Quadrants==<br />
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The [[WMS:Flow Paths and Barrier Coverages|quadrant option]] ensures the water levels are selected for interpolation from different directions instead of being biased by a particular direction. When using this option water elevations used for interpolation are selected equally from the four primary quadrants surround the point of interpolation. If no water levels, or an insufficient number, are found in a quadrant the process proceeds using that many fewer water levels for interpolation.<br />
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==Number of Stages==<br />
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A [[WMS:Search Radius and Flow Distance|number of stages]] used for interpolation must be defined. If the [[WMS:Flow Paths and Barrier Coverages|quadrant option]] is turned on then you will need to specify the number of closest stage points to find within each quadrant. Without the quadrant option then the [[WMS:Search Radius and Flow Distance|total number of nearest stages]] are specified. It is not required that the number specified be found, interpolation will proceed as long as one possible water elevation scatter point is found to meet the specified criteria. For example if 2 stages from each quadrant is specified, and one quadrant has zero possible choices and another quadrant only 1, then 5 points will be used in interpolation.<br />
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==Resulting Data Sets==<br />
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The floodplain delineation tool generates two different types of data sets that can be used for contouring and further analysis with the TIN. First of all a data set of water surface elevations at each TIN vertex contained in the flood plain is calculated and stored. Secondly TIN elevations are subtracted from the water surface elevations to create a flood depth data set. Both, or either of the data sets can be specified for calculation. The data set(s) are TIN data sets and are managed by selecting the active data set for the TIN.<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Differences From Earlier Versions (Version 6.0 and earlier)|Differences From Earlier Versions]]<br />
* [[WMS:Preparing Stage Data|Preparing Stage Data]]<br />
* [[WMS:Stochastic Modeling|Stochastic Modeling]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Read_Stage_File&diff=28520WMS:Read Stage File2008-10-11T15:34:19Z<p>Eshaw: </p>
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<div>Water levels are used in WMS as scattered data sets and can be imported as scattered data set (x, y, z). Files can be in a simple delimited format as shown here within a text file or spreadsheet and imported through the [[WMS:Text Import Wizard|Text Import Wizard]].<br />
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"id" "x" "y" "stg1" "stg2"<br />
1 110 0 45 47<br />
2 110 20 48 49<br />
3 110 40 51 53<br />
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Data can also be formatted in a [[2D Scatter Point Files|scatter point file]], or in the same stage file format used in earlier versions of WMS (version 6.0 and earlier). <br />
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Since water levels are imported as a scatter data set and stored completely separate from the TIN, it is not necessary to match water level locations with TIN vertices (but it is okay if they are). This also removes the necessity of creating stream in the TIN. This flexibility provides the opportunity to incorporate water levels along rivers as well as over the floodplains that are either observed or simulated from a river hydraulic model.<br />
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One of the problems, though, with this new format is that there is no longer a way to "interpolate" stage values between known fixed stages as could be done in previous versions. If you wish to bring forward your data from earlier versions of WMS then you should read the stage file into the older version, interpolate the stage between fixed stage points, and save the stage file (including both the fixed and interpolated stages). Version 7.0 of WMS will then read this stage file and create scattered data points for each of the locations in the old format stage file.<br />
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==Related Topics==<br />
* [[WMS:Overview of Flood Plain Delineation|Overview of Flood Plain Delineation]]<br />
* [[WMS:Delineate Flood Plain|Delineate Flood Plain]]<br />
* [[WMS: Text Import Wizard|Text Import Wizard]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Interpolating_Hydraulic_Model_Results&diff=28519WMS:Interpolating Hydraulic Model Results2008-10-11T15:29:43Z<p>Eshaw: </p>
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<div>After running a 1D Hydraulic model like HEC-RAS, the result is a water surface elevation (or hydrograph for a dynamic solution) at the cross section as indicated by the red circles in the river section shown in the figure below.<br />
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[[Image:image296.gif]]<br />
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The flood plain delineation uses interpolation from the scatter set created by the hydraulic model solution, but the interpolation is not very accurate with such a sparse data set (it often takes 6-8 points to interpolate and with such a sparse data set these six or eight points could cover a long distance within the reach and result in a poor interpolation value). The Interpolate Water Surface Elevations command of the River Tools menu will interpolate for either the 1D-Hydraulic Centerline, or 1D-Hydraulic Cross-sections command new scatter points either at the vertices of the feature arcs (centerline or cross sections) or at a specified distance along the arcs.<br />
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[[Image:image108.jpg]]<br />
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Along cross sections the same value is used at every point along the cross section and along the centerline linearly interpolation is used between consecutive cross sections (this would be consistent with the assumption of a 1D hydraulic model that the water surface is linear between cross sections - if not more detail to the model should be added).<br />
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You specify either the centerline or the cross-sections by making it the active coverage in the Project Explorer prior to choosing this command. The following figure shows the result of interpolating along both the cross sections and the centerline of the model shown above.<br />
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[[Image:image297.gif]]<br />
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==Related Topics==<br />
* [[WMS:HEC-RAS Read Solution|Read HEC-RAS Simulation]]<br />
* [[WMS:Overview of Flood Plain Delineation|Flood Plain Delineation]]<br />
* [[WMS:Preparing Stage Data|Preparing Stage Data]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=File:WMS_DEM_trimmed.png&diff=28427File:WMS DEM trimmed.png2008-10-03T23:32:16Z<p>Eshaw: </p>
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<div></div>Eshawhttps://www.xmswiki.com/index.php?title=File:WMS_DEM_TrimArea.png&diff=28426File:WMS DEM TrimArea.png2008-10-03T23:32:04Z<p>Eshaw: </p>
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<div></div>Eshawhttps://www.xmswiki.com/index.php?title=File:WMSImageSetActiveRgn.png&diff=28423File:WMSImageSetActiveRgn.png2008-10-03T23:20:56Z<p>Eshaw: </p>
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<div></div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Interpolation_of_DEMs_elevations_to_TINs_and_2D_Grids&diff=28420WMS:Interpolation of DEMs elevations to TINs and 2D Grids2008-10-03T22:51:47Z<p>Eshaw: </p>
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<div>==Interpolation to TIN Elevations==<br />
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The Interpolate to TIN command of the DEM menu is used to interpolate the elevations of the DEM to an existing TIN. If TIN vertices lie outside the bounds of the active region of the DEM, no interpolation is performed. This interpolation is done automatically when creating a TIN from feature objects and a DEM is used for a background elevation map. If you are trying to create a TIN from a very large DEM (large number of DEM points) it may be advantageous to create the TIN first and then interpolate elevations from the DEM in a piece-wise fashion by dividing the DEM into several smaller regions and interpolating to the TIN one at a time.<br />
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==Interpolation to 2D Grids==<br />
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Elevations from the DEM can be interpolated to a 2D finite difference grid used for GSSHA models. This is accomplished using the Interpolate to 2D Grid command of the DEM menu.<br />
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==Related Topics==<br />
* [[WMS:Creating TINs|Creating TINs from Feature Objects]]<br />
* [[WMS:Creating Grids|Creating 2-D Grids]]<br />
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{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=File:DEMconversion_opts.png&diff=28410File:DEMconversion opts.png2008-10-03T13:03:31Z<p>Eshaw: </p>
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<div></div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Scatter_Point_Sets&diff=28380WMS:Scatter Point Sets2008-09-30T17:27:10Z<p>Eshaw: </p>
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<div>Each of the points from which values are interpolated are called scatter points. A group of scatter points is called a scatter point set. Each of the scatter points is defined by a set of xy coordinates.<br />
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Each scatter point set has a list of scalar data sets. Each data set represents a set of values that can be interpolated to a grid or TIN. When an interpolation command is selected, the active data set for the scatter point set is used in the interpolation process.<br />
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Multiple scatter point sets can exist at one time in memory. One of the scatter point sets is always designated as the "active" scatter point set. Interpolation is performed from the active scatter point set only. The active scatter point set can be changed using the Project Explorer. Whenever a new scatter point set is read from a file or created, it becomes the active set.<br />
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The most common uses of scatter point sets in WMS is for rainfall gages and the results of hydraulic modeling.<br />
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==Related Topics==<br />
* [[WMS:Terrain Data Module|Terrain Data Module]]<br />
* [[WMS:Preparing Stage Data|Preparing Stages for Floodplain Delineation]]<br />
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<br />
{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Interpolation_to_Grids&diff=28379WMS:Interpolation to Grids2008-09-30T17:21:30Z<p>Eshaw: New page: Once an interpolation scheme has been selected and all of the parameters for the selected scheme have been input, the data associated with the active time step and data set of the active s...</p>
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<div>Once an interpolation scheme has been selected and all of the parameters for the selected scheme have been input, the data associated with the active time step and data set of the active scatter point set can be interpolated to a grid. During the interpolation process, a new data set is constructed for the grid containing the interpolated values.<br />
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The interpolation is done either to the grid nodes or to the grid cell centers depending on whether the grid is a mesh or cell centered grid.<br />
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==Related Topics==<br />
* [[WMS:Interpolation Options|Interpolation Options]]<br />
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<br />
{{WMSMain}}</div>Eshawhttps://www.xmswiki.com/index.php?title=WMS:Interpolation_of_Rainfall_to_Basin_Centroids&diff=28378WMS:Interpolation of Rainfall to Basin Centroids2008-09-30T17:20:51Z<p>Eshaw: New page: The '''Interpolate to Basin Precip''' command in the '''Interpolation''' menu is designed to interpolate rainfall values at scattered points to the xy series representing rainfall for a ba...</p>
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<div>The '''Interpolate to Basin Precip''' command in the '''Interpolation''' menu is designed to interpolate rainfall values at scattered points to the xy series representing rainfall for a basin in either HEC-1 or TR-20. The scattered points typically represent either gaging stations or radar locations for NEXRAD data. Unlike interpolation to grids, this command does not use the active interpolation method, but rather uses the Thiessen method in order to assign the weights of each scatter point for each basin.<br />
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In addition to interpolating rainfall values to basin centroids it is often convenient to interpolate the rainfall values to a grid so that an animation sequence of a storm can be generated. The Bounding Grid options described below is useful for setting up a grid for this purpose.<br />
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==Related Topics==<br />
* [[WMS:Interpolation Options|Interpolation Options]]<br />
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{{WMSMain}}</div>Eshaw