CS(AR)-1/2006-07 : Flood Estimation of Jadukata basin with SCS method

Abstract

Rainfall-runoff relationship is an extremely complex and difficult problem involving many variables, which are interconnected in a very complicated way. Most of the models work best when data on the physical characteristics of the watershed are available at the model grid scale. This kind of data is rarely available, even in heavily instrumented research watersheds. Now Remote Sensing (RS) and Geographic Information System (GIS) make it easier to extract land surface properties at spatial and temporal scales. One of the most widely used techniques for estimating direct runoff depths from storm rainfall is the United States Department of Agriculture (USDA) Soil Conservation Service's (SCS) curve number (CN) method. Its use, however, requires a detailed knowledge of several important properties of the watershed which may not be readily available. Many researchers used information derived from satellite data and integrated them with GIS to estimate SCS CNs and runoff. Routing of runoff in river network may be undertaken using a variety of modelling procedures. The Muskingum method continues to be popular for flood routing. Muskingum routing parameters related to physical and hydraulic characteristics of channel can also be obtained using GIS technique.

Jadukata basin of Meghalaya was selected as the study area. For the digitization of contours, formation of DEM, and extraction of various basin and reach parameters, different GIS softwares like ARC/INFO-8.0.2, ArcView-3.l and AVSWAT was used.