Assessing impacts of Spatio-temporal changes in land use and land cover on the hydrologic response of an Indian Catchment

Abstract

The hydrology of a catchment is sensitive to its intrinsic attributes, such as the land use/land cover(LULC), soil type, and topography, which collectively determines its response to the weather inputs(e.g., precipitation, temperature, radiation, etc.). The dynamic nature of LULC in both space and timeposes a severe challenge in the reliable prediction of the hydrologic response of catchments.However, the spatio-temporal variation in LULC is seldom accounted for in hydrological modelingstudies, which leads to an inaccurate characterization of the watershed. In this study, we haveincorporated dynamic LULC (both in space and time) within the Soil and Water Assessment Tool(SWAT) model, using SWAT-LUT (Land use Update Tool) for the Nowrangpur catchment in India. TheLULC maps corresponding to the years 1985, 1995, 2005, and 2015 are used to generate theintermediate years’ maps via linear interpolation. The future LULC maps till the year 2035 arepredicted using Cellular Automata- Artificial Neural Network (CA-ANN) algorithm in the GISframework. It is observed that there is a reduction in the forest cover from 19.13% in the year 1985to 7.55% in the year 2015, along with the expansion of urban areas and impervious surface from0.36% in the year 1985 to 2.47% in the year 2015. Calibration and validation of the monthlystreamflows are performed by accounting for dynamic LULC within the catchment through SWAT-LUT. The satisfactory performance of the SWAT model is observed in predicting the monthlystreamflows in the Nowrangpur catchment. Further, the comparison of streamflow prediction understatic and dynamic LULC is performed. In these two cases, the observed changes in the values ofwater balance components (i.e., with and without using SWAT-LUT), such as evapotranspiration,surface runoff, infiltration, and water yield, are studied. The changes in the water balancecomponents are attributed to the LULC changes within the catchment. The results indicate that theland use update (to account for the Spatio-temporal variability in LULC) needs to be incorporated todetermine the reliable hydrological response of a catchment.