Evaluation of Hydrological Response of an Agricultural Watershed to Conservation Measures and Land Use Changes: A Case Study

Abstract

An agricultural watershed falling in the catchment of Godavri basin was selected for the study. Paddy, Maize, Cotton, Red gram, and Vegetables are the major crops grown in the watershed. Severe soil erosion consequent degradation of land and lack of water resources for supplementary irrigation and high dependence on rainfed farming leading to poor crop yields were the major problems in the watershed. With a view to address the issues in rainfed farming compounded by increasing adverse effects of climate change, soil and water conservation measures including area and drainage line treatments from ridge to valley were implemented in the watershed from the year 2009 to 2015 with the active participation of local people with facilitation support by a local civil society organization. With the implementation of the conservation measures, visible impact in terms of increased water availability, change in the land use and increased area under cultivation were reported in the watershed. The present study aimed at assessing the hydrological response of the watershed to the conservation measures and land use changes. As the study watershed is an ungauged one, the hydrological response of watershed was simulated with commonly used SCS-CN model duly validated with additional surface storage capacity created in the watershed. The study revealed highly positive impact of conservation measures and land use changes on hydrological behaviour of watershed. The main observed change in hydrological response of watershed was the decrease in the monsoon seasonal runoff by 33% (from 15 % before taking up catchment management measures to 10 % of seasonal rainfall after the project). The conservation measures were found to facilitate storing excess runoff in the watershed itself contributing to improved soil moisture, groundwater recharge and availability of water. Further, the additional storage capacity of 336 cubic m per hectare as estimated from the present hydrological response study was found to be in very close agreement with actual storage capacity of 322 cubic m per hectare, created with different conservation works taken up in the watershed.