Double click the HEC-HMS icon to start the program.The following steps shows how to georeference existing subbasin and reach elements. HEC-HMS uses the name attribute within the subbasin and reach shapefiles when importing information from shapefiles. The user can import subbasin and reach elements from shapefiles, or georeference existing HEC-HMS subbasin and reach elements. Starting with HEC-HMS version 4.3, there are tools to georeference existing subbasin and reach elements using the geospatial information in shapefiles. The basin model was originally defined by delineating subbasins and river reaches using non-GIS tools, therefore, the basin model elements were not georeferenced. Task 1: Import and Georeference Subbasin and Reach Elements Mahoning Creek is downstream of the confluence. The confluence of Stump Creek and East Branch Mahoning Creek is located east of the enclave of Big Run. Primary conveyance streams include: Stump Creek East Branch Mahoning Creek and Mahoning Creek. The Punxsutawney Watershed (400 km 2) is part of the Allegheny River Basin located in western Pennsylvania, USA. In this tutorial, you will perform five tasks to georeference existing subbasin and reach elements before generating a grid cell file and creating a grid region: 1) georeference the project, 2) process terrain information to create a flow direction grid, 3) generate grid cell file 4) create grid region and 5) create links in an HEC-HMS basin model. This tutorial is designed to help the user of HEC-HMS learn how to apply a gridded precipitation dataset to a non-georeferenced project. The user then must specify the default grid region to be used in the basin model. The user can then refer to the grid cell file and create a grid region as a model component. The grid cell file specifies which grid cells are in each subbasin and the properties of each cell including location, area within the subbasin, and distance to the subbasin outlet. When converting a lumped basin into a gridded basin, the user needs to process the terrain data for flow directions, and then generate a grid cell file. In order to use gridded precipitation in the meteorological model and hydrologic methods in the basin model, the user must first georeference the basin model. These older models often use the lump approach for representing subbasins and hydrologic methods rather than the more useful gridded models, which allows the watershed to be represented in greater detail spatially. When background maps of the subbasins and reaches are available the coordinate system information is often missing. These models often do not have background maps of the subbasins and reaches. Many of these existing models are not georeferenced with coordinate system or projection information. There are existing HEC-HMS models that can be updated and improved to utilize gridded precipitation and hydrologic methods. Initial_Gridded_Precip.zip Final_Gridded_Precip.zip Instead, use the structured discretization method - Applying Gridded Precipitation to a Non-Georeferenced Project - Structured Discretization. After HEC-HMS version 4.6.1, the *.mod file should no longer be used. In our case differences between values in the reference dataset and the ones measured in the file to be georeferenced.This tutorial is designed to work with HEC-HMS 4.4 though 4.6.1. Mean fault measure of the differences between values predicted by a model or an estimator and the values actually observed. The more detailed and the more recent the information of reference data the better the result will be.Ĭontrol points Locations with known coordinates in the reference data, which have can be exactly identified in the resources to be georeferenced. It is important to use all the georeferenced available data to achieve a reasonable result. Before starting georeferencing drag one or several georeferenced layers into the map view. Reference data Spatial data that is already georeferenced, the CRS is known. Georeferencing may involve shifting, rotating, scaling or skewing the data. Georeferencing Aligning geographic data to a known coordinate system so it can be viewed, queried, and analyzed with other geographic data, using other data that is already georeferenced.
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