Effect of LULC & Initial Abstraction in Computing Runoff Using SCS-CN Method for Kalangi Watershed in Tirupati District of Andhra Pradesh

Runoff data plays a vital role for planning water control practices, including waterway design, storage facilities, and erosion protection structures. Among various runoff estimation methods, SCS-CN approach integrates the key parameters such as soil infiltrability, land use/land cover and antecedent moisture condition (AMC). LULC effects on CN values by infiltration rate and effect of variation of initial abstraction using SCS-CN by Water Year (WY) model and Rainfall Event (RE) model are studied. Initial abstraction values 0 to 0.3 are explored to understand model responsiveness. Increase in built up area results in decrease in runoff. Initial abstraction (Ia) of less than 0.2S in RE model significantly improves the correlation between rainfall and runoff in watershed runoff calculations.