The Salem County Greenkeepers Plan

Results of flow model in the Salem River Watershed using ArcInfo

The Salem
Why is this
Sources of
Water Quality
Project-Phase I

1995 USGS 1 meter digital aerial ortho-photography of the Salem River Watershed.  The images are mosaiced together and resampled to 5 meters.  GPS'ed dairy farm locations are shown in blue.
Salem River Watershed - DOQQ

The United States Geological Survey (USGS) 30-m DEM data arranged by 7.5 minute quadrangles were downloaded from the internet and mosaicked together, gaps filtered, and then clipped to the watershed boundary.  Projection: UTM NAD83 Units: feet
Salem River - DEM

A flow direction model was created representing the direction of flow from every cell in the DEM.  Processing was done in ArcInfo 7.2.1 using their surface flow functions.  Locating, eliminating, and filling in sinks from the DEM to remove inconsistencies in the DEM was done prior to processing. 
Salem River - Flow direction

From the flow direction grid, a flow accumulation grid was calculated.  The values in this grid represent the number of cells that flow into a given ceel.  Cell values of zero represent high points (all flow is away from that cell), and high values represent flow into a cell.  In essence it builds a stream network.

Using the flow accumulation model, a stream network was created and then converted to a coverage.  All cells where more than 100 cells flowed into them were included.  The image below is an example of flow direction in the watershed of two dairy farms (denoted by barns).
Salem River flow from two dairy farms

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