Carmel River Watershed: Map of Subwatersheds and Gage Locations
From CCoWS Wiki
Subwatershed Data
Metadata
- Original source of data: The National Map [1]
- Map produced by: Nikki Inglis
- Geographic Coordinate System: GCS_North_American_1983
- Datum: D_North_American_1983
ArcGIS Processing Steps
- Clipped the digital elevation model (DEM) into a TIFF comprising the study area (Clip tool)
- Eliminated ocean cells by selecting and extracting DEM values greater than 0 (Extract by attributes tool)
- Filled spurious sinks to account for small errors and imperfections in the DEM (Fill tool) Manually created a new line feature (levee) to correct a flow direction error. In our analysis, a tributary had failed to connect with the Carmel at its actual confluence above a flow gauge, instead connecting further downstream below the gauge site. (Create features)
- Merged the levee feature with the filled DEM .tif (Raster calculator tool)# Created a raster that determined flow direction based on each cell’s steepest downslope neighboring cell (Flow direction tool)
- Created a raster of accumulated flow in each cell based off the flow direction raster (Flow accumulation tool)
- Created stream vectors by calculating pixel count based on a 2 km, 10 km and 30 km area (Raster calculator) Snapped gauging sites to the implied streams (done manually)
- Determined watershed and subwatershed boundaries by calculating the contributing cells above each flow gauge using the flow direction raster (Watershed tool)
- Projected watershed boundaries to a Projected Coordinate System to calculate areas (Raster to polygon and Project tools, Calculate geometry in attribute table)