Impact Analysis of Conservation Structures and Climate Change on Streamflow of Thuthapuzha Watershed, Kerala

Abstract

Hydrological models are increasingly being used to assess how climate change and watershed management practices affect the hydrological processes. In this research, SWAT model was used to analyse the impact of water conservation structures and climate change on streamflow of Thuthapuzha watershed, subbasin of Bharathapuzha located in Kerala, India. Major conservation practices in the study area were modelled as ponds and Kanjirapuzha reservoir was modelled as dam.  The impact of conservation structures on streamflow was evaluated and found that monthly streamflow increased during summer season (9-17%), during which usually the river has a lean flow.  Thus, the conservation structures increase recharging and thereby helps in maintaining a better environmental flow regime. Similarly, the impact of climate change on streamflow was also analysed and the results of the future simulations of streamflow reveal that, river flow increased under all Representative Concentration Pathways (RCP) scenarios with predominant increase in RCP6 scenario (37-60%) followed by RCP4.5 (13-16%) and RCP8.5 (9-16%) from 2021-2070.  For all the scenarios used in the study, due to the predicted increase in rainfall during all the three scenarios, a significant increase in streamflow was observed near the end periods of simulation.