GIS processing tools were used to delineate watershed and catchment basins, flow lines, and stream networks. The tools are Esri ArcGIS (v.10.7) Spatial Analyst tools that used with a digital elevation model (DEM). A DEM is a real world topographic dataset for an area, and is a raster type dataset. In the caseof Homer, we utilized the 2008 Kenai Peninsula Borough LiDAR DEM based on LiDAR data. A sequential set of steps was followed to delineate basins, and derive flow lines, and stream networks. These steps are outlinedsequentially below. NOTE: because the KPB DEM used for this is not a hydroconditioned DEM there are flowlines that may not seem realistic in urban zones due to the fact that topographic barriers in the DEM have not been modified to include culverts or other infrastructure allowing flow.

Steps:

FLOW DIRECTIONS>INKFILLRUN >NEW FLOW DIRECTION>FLOW ACCUMULATION>CREATE WATERSHED>DEVELOP FLOW LINES

Flow lines are features along which water flows, also known as streams, water courses, etc. Flow lines can be delineated from a digital elevation model (DEM) using the output from the Flow Accumulation tool. Flow accumulation in its simplest form is the number of upslope cells that flow into each cell. The first output of flow accumulation may show too much detail, and not show the primary flow lines or streams, and may not seem to reflect reality. In the case of this dataset, 5 iterations utilizing successive refinements of the flow accumulation grid allowed for realistic flow line depiction, except for urban areas where infrastructure allowing flow was not present in the DEM. The final output raster/grid was then converted to vector features as shown in this dataset.