Remote sensing as a tool in regional watershed hydrology

This preliminary study was made to evaluate several facets of a watershed hydrology. The importance of watershed water resources management is briefed, and the application of remote sensing in several watershed environmental problems (relating to the hydrology of the region) enumerated. . A brief discussion on the hydrologic processes and flood studies are outlined with illustrations. Two small watersheds (Fagan Creek and Upstream Aldridge Creek) in the vicinity of Huntsville, Alabama were selected for study. A brief discussion on the regional geology, soils and hydrology is included. Flood frequency estimations under urbanized conditions were made which generally indicated appreciable increase in runoff volume and peak discharges. A method for determining the average curve number based on a grid system is described.

The watershed physiographic parameters (channel slope, ground slope, etc.) were determined primarily from a United States Geological Survey/Tennessee Valley Authority (USGs/TVA) topographic map. The basic land use and land cover data derived from remotely sensed data (1:24,000 color infrared photography) were utilized to estimate the hydrologic parameters: percent of imperviousness, Soil Conserveration Service (Scs) curve number and Manning's roughness coefficient. These are

needed for input for several of the emperical and digital simulation models related to hydrology: flood frequencies, flood peak discharges, water pollution, etc.

The overall emphasis is on the methodology of utilizing remotely sensed data. A brief discussion on a hydrologic model is included, which constitutes an important tool in watershed hydrologic analysis. Preliminary estimates of peak discharges were made from sub-watersheds under estimated and hypothesized input conditions. Samples of "test" results are included.