Manjushree Singh, Vipul Shinde, Ashish Sonawne
NMCA NAU Navsari
The Dang district situated in the south-eastern part of the Gujarat state, faces potable water problems in almost every summer season. The region experiences high annual rainfall (1635mm) compared to the average rainfall of the whole of Gujarat (852.65 mm)(Central Ground Water Board, 2014). Even though, the condition becomes worse during peak summers. Though the region receives heavy rainfall during monsoon months due to steep slopes it causes heavy runoff during monsoon. The district is comprised of three major talukas viz Ahwa, Waghai, and Subir. The people of the district mainly rely on agriculture and the major source of the surface water is the perennial flows in Ambika and Purna rivers in the district. Rainfall runoff is a significant component of the hydrological cycle. In India, accurate information about runoff is limited to a few selected sites. Therefore, estimating runoff is essential for various purposes such as water resource planning, environmental impact analysis, and effective watershed management. In this study, the GIS-based SCS-CN method was applied to estimate runoff from Ambika and Purna Watersheds of the South Gujarat region. Estimation of surface runoff potential for 32 year period (1982 to 2013) indicated a runoff coefficient of 24.40% (446.88mm) for the Purna watershed and 22.80% (419.35mm) for Ambika watershed representing an average annual rainfall of 1833 mm. The estimation of surface runoff potential through the SCS-CN method is an essential tool for sustainable water resources and land management. It provides valuable information to policymakers, planners, and resource managers, enabling them to make informed decisions for the optimal utilization and protection of water resources and the environment. Whereas the developed runoff equations can also be effectively employed to estimate runoff from these watersheds.