INTERNATIONAL JOURNA L OF ENGINEERING SCI ENCES & RESEARCH TECHNOLOGY Runoff Process Using By Overla nd Time of Concentration Model and GIS Modules

The integration strategy for a watershed can be car ried out by various procedures. However a first ste p is ally a resource survey or inventory. This attempts to answer the question of the supply and demand for resources both natural and human resources. Depending upon the area involved, a survey may include socio land capacity/suitability classifications, hydrolog ical assessment including climate characteristics, water use and other parame ters as needed. Runoff is one of the important inte gral part of the integrated watershed management, so for this estima tion of r unoff is required. The rainfall - catchment is a complex and complicated phenomenon governed by large number of known and unknown physiographic factors that vary both in space and t ime. Application of mathematical modeling techniques to t constituent processes involved in the physical proc esses of runoff generation has led to better unders tanding of the processes and their interaction. Conventional hydro logical models for the prediction of runoff particu larly over a rable hydrological and meteorological data. Collect ion of these data is expensive, time consuming and difficult process. ESRI software's Ar c view, Arc Info and Arc GIS 9.1 versions are helpf ul to compute the watershed parameters like slope map, dr ainage ma p, contour map, TIN and DEM etc. And also Remote Sensing technology and Geographical Information Systems (GIS) can augment the conventional methods to a great extent in rainfall runoff studies. In the p resent study a small agricultural watershed rainfal l chosen. The advantage of formulating this model for the watershed is that it enables to generate the r unoff. Once the model is formulated, calibrated and validated, the same can be applied to any watershed to estimate th e runoff, even he sub catchment is ungauged. Keeping these points in view, the rainfall -runoff model, Overland Time of Concentration Model has been formulated and developed. It contains three modules namely Time of Concentration, Rainfall and Soil Moisture module for the estimation of daily runoff. Pamena - I Watershed, Chevella Mandal, Rangareddy District, Andhra Pradesh, India has been considered for the study. It is concluded that the developed OTC model is a fairly good model and it is comparable with the standard mod els considered in the present stud