Program Brief

Statement of Problem: The client required an evaluation of lateral flow on hillslopes and its effect on the distribution of shallow infiltration. The potential focusing of infiltration was expected to affect the performance of an underground high-level waste storage site. Data from a wide variety of field and literature sources needed to be integrated into the Geographic Information System (GIS) to develop model input and to analyze results of surface water and infiltration modeling for a small watershed.

Approach and Accomplishments: The KINEROS2 watershed model, developed by the U.S. Department of Agriculture for surface water runoff and infiltration, was used to evaluate the spatial heterogeneity of shallow infiltration in a 0.25 km² watershed. Field measurements, an ortho-rectified air photograph, a geo-located image of soil depth, a bedrock geologic map, a soil type map, and a geomorphic feature map were assembled in a GIS framework. After a grid was generated, plane and channel element geometric information and hydraulic properties were estimated for each element as input to KINEROS2. Simulations of storm events were aggregated for a 10-year period to evaluate the interplay between geomorphic features, soil depths, and bedrock geology. The results clearly showed that focusing of shallow infiltration in areas below steep slopes would significantly enhance channel infiltration; thus, a broad zone of focused infiltration was likely occurring. A likely zone of focused infiltration on the broad sloping crest of the ridge at the uppermost portion of the watershed also was identified.

Client Benefits: Integration of GIS with numerical process models like KINEROS2 is an efficient approach for generating grid and model hydraulic properties and evaluating model simulation results using all geologic, geomorphic, and topographic information.