Estimation runoff by using curve number (CN) method for Kaushambi micro-watershed, Allahabad region, Uttar Pradesh

Abstract

This study aims to determine the runoff depth using the USDA Soil Conservation Service curve number (SCS-CN) method in Rukma Khurd-I micro-watershed, located between 25o 4' 56.60''-25o 6' 38.09'' N Latitude and 810 56' 48.56''-800 58' 11.37'' E Longitude which is situated at Manikpur block of Chitrakoot district, Uttar Pradesh. A total of 30 single storm events were selected between the years 2008 and 2016 for the study. Antecedent moisture content (AMC) was calculated by taking preceding five days rainfall which gave three conditions AMC I, AMC II and AMC III. Weighted Curve Number for the entire selected micro-watershed was calculated based on site information of the watershed and found to be 90.507 for AMC II. The CN values corresponding to AMC I and AMC III were 80.694 and 95.706 respectively. The runoff for each storm events was estimated following Curve Number method and it is found that among the selected storm events maximum rainfall of 184mm occurred in July 7, 2016 giving runoff value of 170.997mm and minimum rainfall of 35mm occurred in July 13, 2013 with runoff value of 6.242mm. Runoff volume of the micro-watershed for each storm events were also calculated and maximum runoff is found be 775266.971m³. This value will be useful for design of soil and water conservation structures in watershed.