Using ArcHydro for Lower Missouri

The 1km North American HYDRO data, which are usually used for large scale applications, were downloaded from the USGS. Also, the 30m DEMs for sub-basin 1 were downloaded from the USGS.  Arc Hydro was then used to map Flow Direction, Flow Accumulation, Streams, and Drainage Basins from these DEMs. Some of these maps are shown below.

The Flow Direction data set was derived from DEM. It defines the direction of flow from each cell to their steepest down-slope neighbor. Cells with undefined direction of flow represent sinks and have flow directions that are combinations of its neighbors' flow direction values. Flow direction network is a basis for generation of flow accumulation, stream networks, and drainage basins.

Flow Accumulation data, which were developed from the flow direction layer, define the number of cells which flow into each down-slope cell.

The Stream network data set is derived by thresholding the flow accumulation data set. The resulting raster data set is then processed to identify the stream links and each stream link is tagged with its flow accumulation value.

Drainage Basins are derived using the vector stream networks along with the flow direction data set.