Running the tool is also easy. The tool dialog will prompt you for the origin and destination feature classes as well as the optional key fields that will link destination points to origin points.
In the example below, the county seats are related to state capitals by the FIPS code. After the computations are complete, the BasinSlope field in the input Subbasin feature class is populated. The Longest Flow Path tool will create a feature class with polyline features that will store the longest flow path for each sub-basin. Confirm the inputs, and leave the default output name LongestFlowPath unchanged. A new feature class storing longest flow path for each sub-basin is created as shown below:.
Open the attribute table of Longest Flow Path, and examine its attributes. Close the attribute table, and save the map document. The Basin Centroid tool will create a Centroid point feature class to store the centroid of each sub-basin. Select Characteristics Basin Centroid. Note: Center of Gravity Method computes the centroid as the center of gravity of the sub basin if it is located within the sub basin. If the Center of Gravity is outside, it is snapped to the closest boundary.
Longest Flow Path Method computes the centroid as the center of the longest flow path within the sub basin. The quality of the results by the two methods is a function of the shape of the sub basin and should be evaluated after they are generated. A point feature class showing centroid for each sub-basin is added to the map document. As centroid locations look reasonable, we will accept the center of gravity method results, and proceed.
After the computations are complete, open the attribute table of Centroid to examine the Elevation field. The centroid elevation update may be needed when none of the basin centroid methods center of gravity or longest flow path provide satisfactory results, and it becomes necessary to edit the Centroid feature class and move the centroids to a more reasonable location manually. This creates a new polyline feature class showing the flowpath for each centroid point along longest flow path.
These parameters include SCS curve number, time of concentration, channel routing coefficients, etc. You can specify the methods that HMS should use for transform rainfall to runoff and routing channel routing using this function. Confirm input feature classes for Subbasin and River, and click OK.
You can open the attribute table of subbasin feature class to see that the subbasin methods are added to LossMet, TransMet, and BaseMet fields, respectively. The Muskingum method is added to RouteMet field in the River feature class.
You can treat these methods as tentative which can be changed in HMS model. River Auto Name. The River Auto Name function assigns names to river segments. Confirm the input feature class for River, and click OK. Basin Auto Name. The Basin Auto Name function assigns names to sub-basins. Confirm the input feature class for sub-basin, and click OK. These parameters are assigned using Subbasin Parameters option.
This function overlays subbasins over grids and compute average value for each basin. We will explore only those parameters that do not require additional datasets or information.
Add cngrid curve number grid from Layers folder to the map document. You will get a menu of parameters that you can assign. After the computations are complete, you can open the attribute table for subbasin, and see that a field named BasinCN is populated with average curve number for each sub-basin.
Note: We will skip parameters associated with computing rainfall as these numbers should come from detailed analysis of the watershed.
However, if you are interested, you can explore these functions because you have all the necessary data for their execution. The CN Lag Method function computes basin lag in hours weighted time of concentration or time from the center of mass of excess rainfall hyetograph to the peak of runoff hydrograph using the NRCS National Engineering Handbook curve number method.
This function populates the BasinLag field in the subbasin feature class with numbers that represent basin lag time in hours. Take a look at attribute tables of River and Subbasin feature class to see what fields are populated, and what they mean in hydrologic modeling. Map to HMS Units. This tool is used to convert units. Confirm the input files, and click OK.
Note: Due to some unknown reasons, if you get an error message at this point saying field cannot be added to a layer, save the map document, exit ArcMap and open the document, and try again. In the next window, choose English units default from the drop-down menu, and click OK.
Check Data. This tool will verify all the input datasets. Confirm the input datasets to be checked, and click OK. You should get a message after the data check saying the check data is completed successfully as shown below. You can also look at the log file and make sure there are no errors in the data by scrolling to the bottom of the log file as shown below:. If you get problems in any of the above four categories names, containment, connectivity and relevance , you can look at the log file to identify the problem, and fix them by yourself.
This version of HecGeoHMS apparently gives error with river connectivity even if the rivers are well connected. Therefore, check the data carefully, and if you think everything is OK, ignore the errors if you get any for connectivity and proceed.
HMS Schematic. Confirm the inputs, and click OK. Add Coordinates. This is useful for exporting the schematic to other models or programs without loosing the geospatial information. Prepare Data for Model Export. Confirm the input Subbasin and River files, and click OK. This function allows preparing subbasin and river features for export. Background Shape File. This function captures the geographic information x,y of the subbasin boundaries and stream alignments in a text file that can be read and displayed within HMS.
Two shapefiles: one for river and one for sub-basin are created in the project folder. Click OK on the process completion message box. Basin Model. This function will export the information on hydrologic elements nodes and links , their connectivity and related geographic information to a text file with. The output file CedarCreek. You can also open the. Meteorologic Model. We do not have any meteorologic data temperature, rainfall etc at this point.
We will only create an empty file that we can populate inside HMS. HMS Project. This function copies all the project specific files that you have created. Provide locations for all files. Even if we did not create a gage file, there will be a gage file created when the met model file is created. Give some name for the Run, and leave the default information for time and time interval unchanged.
After you respond to that message a project file report will be displayed as shown below:. Typically, you will have to modify meteorologic and basin files to reflect field conditions before actually running the HMS model. Close the report. Browse to CedarCreek. Expand the Basin Models folder and click on CedarCreek. This will display the Cedar creek schematic. If you expand the CedarCreek basin in watershed explorer, you will see the list of junctions, reaches and subbasins.
You can click on any reach and see its associated methods. For example, when you click on a Reach R , you will see that Muskingum routing method is associated with it.
Manipulating data in HMS, populating the Meteorologic file, and running the model is beyond the scope of this tutorial. Save your HMS project. Hydraulic Modeling Workflow. Additional datasets that may be useful are aerial photograph s and land use information. It is then cumbersome to find out which feature classes were used during pre-processing, and which feature classes contain results for visualization. To create a geometry file, you need terrain elevation data.
You must have the same coordinate system for all the data and data frames used for this tutorial or any GeoRAS project. You can check this by right-clicking on the data frame and looking at its properties. After creating RAS layers, these are added to the map document with a pre-assigned symbology. Since these layers are empty, our task is to populate some or all of these layers depending on our project needs, and then create a HEC-RAS geometry file.
Creating a river centerline. Let us first start with river centerline. The river has different tributaries as shown below. Zoom-in to the most upstream part of the ceedar creek tributaries. To create the river centerline in River feature class , start editing, and choose Create New Feature as the Task, and River as the Target as shown below:.
Using the Sketch tool highlighted above , start digitizing the river centerline from upstream to downstream until you reach the intersection with Tule Creek tributary. To digitize the upper Baxter River reach, click in the direction of flow and double click when done at intersection with Tule Tributary. If you need to pan, click the pan tool, pan through the map and then continue by clicking the sketch tool do not double-click until you reach the junction.
After finishing digitizing the upper Baxter Reach, save the edits. Before you start digitizing the Tule Creek tributary, modify some editing options. We are modifying the editing environment because when we digitize the Tule tributary we want its downstream end coincide with the downstream end of the upper Baxter Reach. Close the snapping box, and then start digitizing the Tule Tributary from its upstream end towards the junction with the Baxter River. When you come close to the junction, zoom-in, and you will notice that the tool will automatically try to snap or hug!
Double click at this point to finish digitizing the Tule Tributary. Save edits. Finally, digitize the lower Baxter reach from junction with the Tule Tributary to the most downstream end of the Baxter River. Again make sure you snap the starting point with the common end points of Upper Baxter Reach and Tule Tributary.
Save edits, and stop editing. Snapping of all the reaches at the junction is necessary for connectivity and creating HEC-RAS junction so make sure the three reaches are snapped correctly. After the reaches are digitized, the next task is to name them. We can treat the main stem of the Baxter River as one river and the Tributary as the second river.
With the button active, click on the upper Baxter River reach. You will see the reach will get selected, invoking the following window:.
Click on the tributary reach, and use Tule Creek and Tributary for River and Reach name, respectively. Now open the attribute table of River featureclass, and you will see that the information you just provided on river and reach names is entered as feature attributes as shown below:. Also note that there are still some unpopulated attributes in the River feature class FromNode, ToNode, etc. Before we move forward let us make sure that the reaches we just created are connected, and populate the remaining attributes of the River feature class.
This will populate the remaining attributes. Now open the attribute table for River, and understand the meaning of each attribute. HydroID is a unique number for a given feature in a geodatabase. The River and Reach attributes contain unique names for rivers and reaches, respectively. The FromNode and ToNode attributes define the connectivity between reaches. For example, each river has a station number of zero at the downstream end, and is equal to the length of the river at the upstream end.
Bank lines are used to distinguish the main channel from the overbank floodplain areas. Information related to bank locations is used to assign different properties for crosssections. Creating bank lines is similar to creating the channel centerline, but there are no specific guidelines with regard to line orientation and connectivity - they can be digitized either along the flow direction or against the flow direction, or may be continuous or broken.
To create the channel centerline in Banks feature class , start editing, and choose Create New Feature as the Task, and Banks as the Target as shown below:. Although there are no specific guidelines for digitizing banks, to be consistent, follow these guidelines: 1 start from the upstream end; 2 looking downstream, digitize the left bank first and then the right bank.
Digitize banks for all three reaches and save the edits and the map document. Creating the Flowpath Layer. The flowpath layer contains three types of lines: centerline, left overbank, and right overbank.
The flowpath lines are used to determine the downstream reach lengths between cross-sections in the main channel and over bank areas. If the river centerline that we created earlier lie approximately in the center of the main channel which it does , it can be used as the flow path centerline. To create the left and right flow paths in Flowpaths feature class , start editing, and choose Create New Feature as the Task, and Flowpaths as the Target as shown below:.
Use the sketch tool to create flowpaths. The left and right flowpaths must be digitized within the floodplain in the downstream direction. These lines are used to compute distances between cross-sections in the over bank areas. Again, to be consistent, looking downstream first digitize the left flowpath followed by the right flowpath for each reach. After digitizing, save the edits and stop editing. Now label the flowpaths by using the Assign LineType button.
Click on the button notice the change in cursor , and then click on one of the flow paths left or right, looking downstream , and name the flow path accordingly as shown below:. Label all flow paths, and confirm this by opening the attribute table of the Flowpaths feature class. The LineType field must have data for each row if all flowpaths are labeled.
Cross-section cutlines are used to extract the elevation data from the terrain to create a ground profile across channel flow. The intersection of cutlines with other RAS layers such as centerline and flow path lines are used to compute HEC-RAS attributes such as bank stations locations that separate main channel from the floodplain , downstream reach lengths distance between crosssections and Mannings number.
Therefore, creating adequate number of cross-sections to produce a good representation of channel bed and floodplain is critical. Certain guidelines must be followed in creating cross-section cutlines: 1 they are digitized perpendicular to the direction of flow; 2 must span over the entire flood extent to be modeled; and 3 always digitized from left to right looking downstream. Even though it is not required, but it is a good practice to maintain a consistent spacing between cross sections.
In addition, if you come across a structure eg. Structures can be identified by using the aerial photograph provided with the tutorial dataset. For example, we will use one bridge location in this exercise just downstream of the junction with tributary as shown below bridge location is shown in red :. Follow the above guidelines and digitize cross-sections using the sketch tool.
While digitizing, make sure that each cross-section is wide enough to cover the floodplain. This can be done using the cross-sections profile tool. Click on the profile tool, and then click on the cross-section to view the profile.
For example, if you get a cross-section profile shown in Figure A below, then there is no need to edit the cross-section, but if you get a cross-section as shown in Figure B below, then the cross-section needs editing. Note: This tool stops the edit session so you will have to start the edit session every time after viewing the cross-section profile.
After digitizing the cross-sections, save the edits and stop editing. Since all these attributes are based on the intersection of cross-sections with other layers, make sure each cross-section intersects with the centerline and overbank flow paths to avoid error messages.
This tool will assign station number distance from each cross-section to the downstream end of the river to each cross-section cutline. This tool assigns bank stations distance from the starting point on the XS Cutline to the left and right bank, looking downstream to each cross-section cutline. This tool assigns distances to the next downstream cross-section based on flow paths.
The cross-section cutlines are 2D lines with no elevation information associated with them Polyline. When you used the profile tool earlier to view the cross-section profile, the program used the underlying terrain to extract the elevations along the cutline.
After this process is finished, open the attribute table of XSCutLines3D feature class and see that the shape of this feature class is now PolylineZ. Creating Bridges and Culverts. After creating cross-sections, the next step is to define bridges, culverts and other structure along the river. Since we used aerial photograph while defining the crosssections, our job of locating the bridge is done. Using the sketch tool on the editor toolbar, the digitize bridge location just downstream of the tributary junction.
Save your edits and stop editing. Besides these attributes, you must enter additional information about the bridge s such as the name and width in its attribute table as shown below.
A new feature class Bridges3D will be created. You can check it is PolylineZ by opening its attribute table. Creating ineffective flow areas. For example, areas behind bridge abutments representing contraction and expansion zones can be considered as ineffective flow areas.
The position of ineffective areas will be stored in a new table named IneffectivePositions. Leave current user elevations unchecked, and Click OK. Open the attributes of the IneffectivePositions table shown below to understand how this information is stored. BegElev and EndElev are the elevations of the first and last intersecting points of the ineffective area with the crosssection. Since you left the UserElev box unchecked there are no values in this field. Obstructions represent blocked flow areas areas with no water and no flow.
For example, buildings in the floodplain and levees are considered obstructions. We can add blocked obstructions to our study by using building locations in the aerial photograph. Use the Sketch tool to define the blocked obstruction, save edits and stop editing.
Similar to Ineffective flow areas, the positions and elevations of the intersection of this obstruction with cross-sections needs to be stored in a table. Leave the default values in the Blocked Obstructions window, and click OK.
You will notice that a new table BlockedPositions will be added to the map document, and its content are identical to IneffectivePositions table. Ideally you will store this information in the LandUse feature class added to the map. In addition, HEC-GeoRAS requires the land use polygons to be non multi-part features a multipart feature has multiple geometries in the same feature.
The issue of non multi-part features is taken care of for the tutorial dataset. Open the Manning table, and see how the values are stored. Similar to previous tables, the data are organized as the feature identifier XS2DID , its relative station number and the corresponding n value as shown below:. Spider diagrams also provide a quick and simple method to see if stores are cannibalizing each other.
The graphic below shows unweighted desire lines drawn from each customer to its store. The desire lines are drawn as different colors for each store. Weighted values aren't used to calculate desire lines but to display the lines differently. The thickness or color of each desire line is proportional to the weighted variable for that particular customer. Spider diagrams can be weighted by any number in the customer database.
For example, a hospital might weight each patient line by the number of hospital stays per year.
0コメント