GEOSPATIAL ANALYSIS OF PLANNED INDIAN DAMS ON RIVER CHENAB AND ITS HYDROLOGICAL AND AGRICULTURAL IMPACTS ON PAKISTAN

Abstract

River Chenab catchment is shared by India, Jammu & Kashmir and Pakistan, whose flows are governed by Indus Water Treaty. The study focuses on geo-spatial analysis of existing / planned Indian Dams on River Chenab, their hydrological, agricultural and water regulation. The study area comprises Chenab catchment upto Marala and canal command areas of Upper and Lower Chenab Canals. Remotely sensed temporal images of Land Sat and Digital Elevation models were used for areal and volumetric assessments of Indian dams. Flow variations in River Chenab were analyzed by using discharge data of the last 36 years at Marala. Crop pattern change from 2006 to 2016 was studied using Moderate Resolution Image Spectro Radiometer imageries at 8-day interval. Based on NDVI curves, district wise land cover classification was carried out. Crop water deficiency was worked out based on irrigation water and effective precipitation. Change in hydraulic gradient from 2006 to 2014 was also analyzed. Trend analysis for historic flows at Marala for the last 36 years averaged 31,579 MCM with a downward trend reduced to 28,936 MCM in the last 10 years, attributable to commissioning of Baghliar and Dulhasti Dams. Land cover classification for 2006 and 2016 yielded an accuracy assessment R-squared values of 0.876 and 0.817 respectively for major crops. Comparison showed an overall increased cropping intensity, with 13% increase in wheat, 134% increase in cotton, decrease of 2.83% in sugarcane, 3.89% decrease in rice. An increase in annual crop water demand of 2,674 MCM. Crop water deficiency showed an increase in water deficiency by 1,121 MCM. With the present trend, predicted crop water deficiency has been estimated to increase from 11,968 MCM in 2016 to around 12,428 MCM in the next five years. Analysis for change in hydraulic gradient showed a reduction in water table in about 14% areas and in 64% areas, the water table remained unchanged.