Assessment of Land Cover Changes and Climate Variability Effects on Catchment Hydrology Using a Physically Distributed Model

Abstract

Land use/land cover, along with climate variability, play vital roles in hydrological functionality of catchments and are leading threats to inter-related hydrological processes. In the current study, a physically distributed Soil and Water Assessment Tool model is used to investigate the impact of historical changes on the hydrologic response of the Damodar catchment (Jharkhand, India) in terms of inflow to the Panchet reservoir. The model was validated for the monthly runoff and inflow at the outlets of four watersheds and three reservoirs in the Damodar catchment before the assessment of changes in inflow at the Panchet reservoir was performed. The analysis of land cover thematic maps prepared using satellite images of Landsat 4, 5 and 7 showed that from 1972 to 2001, the land cover in the Damodar catchment changed considerably. The interpretation of land cover results indicates that significant increases in settlements (140%), waterbodies (98.42%) and agricultural land (26.71%), along with decreases in wasteland (32.63%) and forest (15.28%), occurred due to development. The Mann–Kendall test was used for measuring the rainfall and temperature for the Damodar catchment, which showed that this region became drier during 1970–2005, with decreases in the annual rainfall and increases in the mean temperature. A simulated hydrological impact under land cover dynamics and climate variability in the historical time frame of 1970–2000 using the model revealed a gradual increase of 26.16% in the Panchet reservoir inflow. The study revealed that the increased inflow is relatively greater under the influence of climate variability due to changes in rainfall and temperature, rather than land cover, that were observed over the region.