Geomorphic GIS database for runoff coefficient determination

摘要

The use of remote sensing and Geographic Information System (GIS) to facilitate the estimation of runoff from watershed and agricultural fields has gained increasing attention in recent years. This is mainly due to the fact that a good rainfall-runoff model has to include both spatial and geomorphologic variations in the model. Remote sensing and GIS are excellent tools for acquiring and managing spatially distributed data. The USDA Soil Conservation Service Curve Number (SCS-CN) method is being used in this study for determining the runoff coefficient. Runoff Curve Number (CN) is determined based on the factors of hydrologic soil group, land use, land treatment, and hydrologic conditions. GIS is being used to provide quantitative measurements of drainage basin morphology for input into runoff models so as to estimate runoff coefficients. During the 1960s the Kissimmee River, Florida, was channelized into a 90-km-long, 9-m-deep canal. Thus, S-65A sub-basin in the Kissimmee River Basin was used as an example to demonstrate the possibility of integrating the remotely sensed images and other hydrologic related data with the GIS technique to estimate the runoff coefficient. This process of geomorphic GIS database development for runoff coefficient determination from both digital orthophoto quarter Quadrangle (DOQQ) data and Landsat TM images is presented in this paper using ARC/INFO system and other image processing softwares.