Relation Between Runoff Curve Number and Irrigation Water Requirement

This paper proposes a relationship between Soil Conservation Services runoff curve number (CN) and crop water requirement/irrigation water requirement (IWR) for Seonath river basin (area = 30,860 sq km) falling in Chhattisgarh State (India) considering rain-fed irrigation. It is derived empirically from long-term (30 years, 1960–1989) rainfall–runoff data and validated on the remaining data of 20 years from 1990 to 2010. The relationship was derived with coefficient of determination ( R 2 ) of 0.970 for monsoon season and 0.926 for post-monsoon season. It was validated with R 2 of 0.957 and 0.954 for monsoon and post-monsoon seasons, respectively, indicating the existence of a strong CN–IWR relationship.