Environmental Study of Water Reservoirs for the Watershed Management in Pakistan

Abstract

Water reservoirs in most parts of the world face the problem of sedimentation. Environmental impacts and land-use changes/landslide have enormous potential to generate more sediment load in water reservoirs. Hence, the capacity of water reservoirs in Pakistan has been constantly reducing due to sedimentation. In this study, we have computed the environmental impacts on sedimentation load in Tarbela and Mangla water reservoirs using multi-satellite and ground-based data. The total drainage area of watershed is calculated using Shuttle Radar Topographic Mission data. Satellite data from NOAA-AVHRR are used to monitor urban development and changes in vegetation area, while MODIS data are used to estimate the snow area in the watershed region. Normalized Difference Vegetation Index is used to estimate the temporal changes in vegetation cover, whilst principle component analysis is applied to monitor urban changes in watershed region. Similarly, snow cover area in the study region is estimated using Normalized Difference Snow Index algorithm. Rainfall data obtained from Pakistan Meteorological Department are used to evaluate the relationship between sedimentation deposited in water reservoirs and annual rainfall amount. Results of the current study reveal that increase in urban development and high amount of precipitation has direct relationship with the load of sedimentation, while amount of vegetation has inverse relationship with the load of sedimentation in water reservoirs of the country.