Christina Watershed Project
Angela M. Watson and John Mackenzie

The Christina Watershed is the principal drainage area providing surface water to Northern New Castle County, Delaware. The long-term adequacy of surface water supplies to New Castle County is a focus of public concern, since the county is so highly dependent on surface supplies. New Castle County is now evaluating various options to maintain adequate water supplies during periods of drought.

This project, developed in cooperation with the Water Resources Agency for New Castle County, Delaware, generated 30M resolution digital elevation models for West Grove, Coatesville and Morgantown (PA) 7.5-minute quads, and combined these DEM's with seven existing Delaware DEM's published by Mackenzie, and nine USGS DEM's obtained through the Water Resources Agency, to create a detailed composite terrain model of the entire Christina Basin.

Composite DEM data file (GRASS ASCII format, gzipped, 2.47MB): christina_dem_asc.gz

The composite DEM was analyzed to obtain an accurate delineation of the watershed's sub-basins and quantify cumulative surface water flows from those sub-basins.

The Brandywine River drains the northeast 57.5% of the watershed, joining the Christina River in Wilmington. The White Clay and Red Clay Creeks drain the lower piedmont area. The Christina Creek drains the southernmost basins in the piedmont/coastal plain transition zone, joins the White Clay Creek at Churchman's Marsh, and flows northeast to Wilmington and the Delaware River. The principal basin areas are:

					Pct. of		Sq. Mi		Percent 
Sub-Basin		Sq. Mi		Basin		in DE		in DE
----------------	-------		-------		------		--------
Christina River		 24.02		 4.27 %		 24.02		100.00 %
Brandywine River	323.60		57.50 %		 22.97		  7.10 %
Red Clay Creek		 53.74		 9.55 %		 21.03		 39.13 %
White Clay Creek	108.05		19.20 %		 46.16		 42.72 %
Christina Creek		 53.34		 9.48 %		 42.80		 80.24 %
----------------	-------		-------		------		--------
TOTAL WATERSHED		562.73		100.00 %	156.98		 27.90 %

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