Estimation of Surface Runoff of Machhu Dam Iii Chatchment Area, Morbi, Gujarat, India, using Curve Number Method and GIS

Machhu River is one of the major North’s flowing river of Saurashtra regions in Gujarat state. The catchment area of Machhu III lies in Machhu River Basin in Morbi taluka of Rajkot district. This catchment area falls under the category of sub watershed as per the size (24212 hectare) and thus curve number method has been applied for estimating runoff using GIS technology. The Curve Number (CN) has been estimated for Machhu Dam III drainage basin using a combination of land use (Crop land, Fallow land, Lakes / Ponds, Land with Scrub, Land without Scrub, Industrial Waste, Prosophis, Reservoirs, River, Towns/cities (Urban), Villages (Rural)),Soil (Fine Sand, Clayey), and Antecedent Soil Moisture Condition (AMC). Within this catchment number of land cover type and soil type exist. The original soil type map has been converted to a map of Hydrologic Soil Groups (HSG) using the published conversions. Weighted area curve number has been determined in order to find a representative curve number by integrating attributes of various thematic layers in arc GIS using the areas of the different land cover and soil types as weighting factor