The Effect of Inter-Basin Water Transfer on the Water Resources of Betwa Basin, India

English Abstract:

This investigation has been carried out to analyse the effect of inter-basin water transfer on the water balance of the Betwa basin (43500 km²), India. The Providing Regional Climates for Impacts Studies - Regional Climate Model (PRECIS-RCM) data in conjunction with the Soil and Water Assessment Tool (SWAT) model (Semi distributed model) has been employed to examine the long term effects of inter-basin water transfer on the basin water resources. Analysis of water balance was carried out dividing the whole Betwa Basin into three parts. The upper basin was considered as rainfed and this area is denoted by “Area-A”. In lower part of the basin, the existing major irrigation projects fulfilling irrigation and municipal/industrial needs are considered and this area is denoted by “Area-B”. The third “Area-C” represents the Dhasan catchment irrigated also through small irrigation schemes. Assuming that the present situation of irrigation in the Betwa basin shall prevail till 2035 and Ken- Betwa Link Plan (KBLP) will establish afterwards, this study considers two scenarios: Long Term Part-I (LTP-I) for year 1976-2035 and Long Term Part-II (LTP-II) for year 2036-2095. Water resources of LTP-I (1976-2035) and LTP-II (2036-2095) scenarios were compared for all sub-areas, viz., Areas-A to C. Precipitation and evapotranspiration has been increased in all areas. Change in these parameters influences all the other water balancing parameters of the basin. The effect of implementation of the KBLP on different components of water balance during 2036-2095 was also evaluated considering that no man-made changes would occur in the basin. Results reveals that there will be a considerable decrease in surface runoff, transmission losses, and total water yield in Area-A (upper basin), largely because of trapping of water in upper basin through different (but likely) irrigation schemes. In addition, lateral flow, groundwater contribution and percolation will increase significantly. The water balance is almost similar for Areas-B and C in both scenarios. Thus, this study in different scenarios indicates significant effect of the KBLP in upper basin, but without affecting previous commitments of the water withdrawals from the lower basin.