Estimation of runoff for agricultural watershed using SCS curve number and geographic information system

Estimation of runoff for agricultural watershed using SCS curve number and geographic information system

Ashish Pandey
Lecturer, Agricultural Engineering,Soil and Water Conservation Engineering, Watershed Modeling using RS and GIS
E-mail: apandey@ nerist.ernet.in, p.ashish@lycos.com

P. P. Dabral
Assistant Professor, Agricultural Engineering, Soil and Water Conservation Engineering, Watershed Hydrology
E-mail:ppd@nerist.ernet.in
Phone: +91-360-257401-5 Ext. 6210 (O), +91-360-257 357 (R)
Fax: +91-360-244 307 (O)

Department of Agricultural Engineering, NERIST, Nirjuli, Itanagar, Arunachal Pradesh India-791 109,

V.M. Chowdary
Regional Remote Sensing and Service Centre, Kharagpur

B.C.Mal
Department of Agricultural and Food Engineering, IIT, Kharagpur, India-721 302

Introduction
A watershed is the area covering all the land that contributes runoff water to a common point. It is a natural physiographic or ecological unit composed of interrelated parts and functions. In India, the availability of accurate information on runoff is scarcely available in few selected sites. However, quickening of the watershed management programme for conservation and development of natural resources management has necessitated the runoff information. Advances in computational power and the growing availability of spatial data have made it possible to accurately predict the runoff. The possibility of rapidly combining data of different types in a Geographic Information System (GIS) has led to significant increase in its use in hydrological applications. The curve number method (SCS, 1972), also known as the hydrologic soil cover complex method, is a versatile and widely used procedure for runoff estimation. This method includes several important properties of the watershed namely soil's permeability, land use and antecedent soil water conditions which are taken into consideration. In the present study, the runoff from SCS (Soil Conservation Services) Curve Number model modified for Indian conditions has been used by using conventional database and GIS for Karso watershed (Hazaribagh, India).

Materials and Methods

Study area
The study area, Karso watershed, which lies within Damodar Barakar catchment is situated between 85° 23' 30" to 85° 28' E longitude and 24° 12' to 24° 18' N latitude with an elevation ranging from 390-650 m above MSL (Mean Sea Level) and extends over a total area of 2793 ha. The watershed receives an average annual rainfall of 1300 mm and more than 80% of the rainfall is received during the monsoon season (June to September). The minimum and maximum temperature varies in the range of 30 C to 420 C. The mean relative humidity varies from a minimum of 40% in April to a maximum of 85% in the month of July. The overall climate of the area can be classified as sub-humid tropical. The soil is mainly sandy loam type occupying the maximum area with a land slope varying from 0 to 8 %, maximum slope of some hilly parts of the watershed is upto 22% and the soil depth ranges from 0 to 45 cm.

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