Abstract
This study assessed the groundwater storage potential of degraded meadows along the main course of Last Chance Creek (LCC). The stream is located in the portion of the North Fork Feather River Watershed that lies in the Basin and Range geomorphic province of northeastern California. The project focused on former meadow areas greater than 50,000 square meters, and employed several software tools, primarily Arc-GIS and Google Earth, to survey the main branch of LCC and to create the criteria necessary to define the meadow extents. These criteria were subsequently employed to select and delineate the eleven degraded meadow areas for this project. ArcGIS tools were used to develop an initial set of digital elevation models (DEMs) for the surface elevation of each meadow’s surface. A second set of DEMs was created for the water table surfaces beneath each meadow. The approach for this set used a triangular irregular network (TIN) tool in ArcMap to create a hypothetical sediment trough for each meadow with a triangular cross section. This geometry reflected the elevation of the water table which was assumed to rise in a straight line from its lowest point at the bottom of each meadow’s deepest incised gully to the surface elevation at the meadow edges on both sides of the gully. Once these two sets of DEMs were constructed for each meadow, the Cut-Fill tool of ArcGIS was employed to produce a raster data set whose values reflected the sediment volume in the triangular trough of meadow sediment potentially available for groundwater storage. This volume was then factored by assumed total porosities and effective porosities to determine the volume of potentially storable groundwater. An alternative mathematical approach was also used to calculate volumes based on a hypothetical sediment trough with a rectangular cross section reflecting an assumed constant water table elevation. Together, these two approaches bracket the maximum and minimum groundwater storage potential in eleven degraded meadow areas of Last Chance Creek. Results suggest the methodology used in this study can be used with existing and assumed data to provide a quick and inexpensive screening tool for assessing the groundwater potential for meadow restoration projects.