Estimation of Runoff Potential by the Application of Curve Number Method in GIS Platform

Abstract

Estimation of direct runoff is essential for planning and development of watershed. In this study estimation of the same is carried out by applying Soil Conservation Service-Curve Number (SCS-CN) model technique with Geographic Information System (GIS) approach. The SCS-Curve Number model is a hydrological model which is widely used for estimation of runoff volume generated from the rainfall event. The said model mathematically describe the rainfall – runoff relationship and uses rainfall data and Curve Number (CN) as the inputs. The Curve Number is an empirical index depends on the soil complex, land use and hydrological condition of the area. The SCS-CN method with GIS approach has been adopted for predicting the runoff volume in the catchment of upper Mahanadi, which is upstream of the confluence of Mahanadi and Pairi River. The catchment area under consideration is 8086 sq.km. The study area climate condition is tropical monsoon type which receives the normal annual rainfall of 1360 mm. The maximum precipitation about 86% of the total precipitation, observed in the monsoon period from July to Mid of September. Survey of India (SOI) topographic sheets and Indian Remote Sensing satellite image LISS-III were used to prepare thematic maps of the study area. Thematic maps and hydrological data were used to generate Curve Number map and Hydrological Soil Group map. The SCS-CN method is very useful to compute runoff volume from the land, which quatify the direct drain to the river or streams. The outcome of this study is useful for watershed planning and development effectively for the study area.