General Workflow

The general workflow for setting up a new WAM scenario is to process the datasets before importing them to the WAM GIS Database. Depending on the user's situation, this may involve creating an intermediate geodatabase or just using a set of shapefiles that have been copied to a folder. The model domain needs to be decided upon before starting processing. Within the model domain, the next step is to define the sub-basin boundaries. Sub-basin boundaries are used by WAM to define catchments within the larger model domain, for example a Hydrologic Unit Code (HUC) 8 river basin may be used to define the model domain and HUC 12 basins to define the sub-basins. WAM will not allow overland flow to cross sub-basin boundaries; all flow within a sub-basin is directed to reaches within the sub-basin. Consequently, each sub-basin must have at least one reach within the stream network. Once overland flow has been directed into the stream network, flow within streams can cross sub-basins. Besides using sub-basins defined by an external dataset, the user may decide to create a sub-basin to ensure that overland flow does not cross local man-made features such as berms or stormwater treatement basins.

The details for processing each GIS dataset is discussed in the following sections. While each feature class in the WAM GIS Database has required attributes (fields), additional attributes can be added or copied from an existing dataseet as desired by the user. For example, the Soils feature class requires a SoilID field, but other fields such as the drainage class or the hydrologic group may be included if the user wants.

It is helpful to create a new geodatabase named something like "Data_Setup", separate from the WAM GIS Database, to gather and process the various feature classes that need to be imported. Processing steps will include using various ArcMap geoprocessing commands (e.g., clipping) and the addition of attributes to the datasets that are needed to run WAM. All feature classes should be assigned the same projection that will be used for the WAM simulations. It is also helpful to create a new separate ArcMap document for the processing steps that need to be done and name it appropriately - e.g., Data_Setup_Map.mxd.

During import, the basin boundary feature class is by default created automatically by merging all of the sub-basins into a single feature (see Sub-Basin Boundaries). The basin boundary can then used to clip the land use, soils, utility zone, irrigation source, and topography DEM so that each polygon feature class fits exactly within the basin boundary. While the clipping can be performed during the import, it is strongly suggested that clipping be done prior to import since it is much faster to clip using the standard ArcMap geoprocessing Clip function. The workflow suggested here is to:

  1. Import the sub-basin feature class, and make sure that the import step specifies that the imported sub-basin feature class is used to define the basin boundary during processing.

  2. After importing, check to make sure the sub-basin feature class was imported correctly and the basin boundry was generated correctly (as a single polygon)

  3. Use the newly created basin boundary to clip the other feature layers (land use, soils, etc.) before importing them.

  4. Import the remaining feature classes. While importing multiple datasets simultaneously is possible, it is recommended that they be imported one-at-a-time if any errors happen.

  5. Important: If a dataset is imported and the user then decides to modify the original dataset and re-import, first use the ArcMap editor to delete all features in the target feature class before re-importing. Otherwise, overlapping features will be generated which will cause issues later.