Planning water resource management in Pishin-Lora river basin of Balochistan using GIS/RS techniques

The recent drought (1998-2004) in water deficient province of Balochistan (the largest province of Pakistan) affected the availability of seasonal rainwater and vegetation cover. Analysis of the spatial rainfall computed through spatial interpolation of point rainfall depicted a reduction of about 53-85 percent and 66-90 percent in volumes of rainwater during summer and winter seasons of the drought period, respectively. Spatio-temporal analysis of the vegetation cover carried out through land cover classification of satellite images revealed a reduction of up to 31 percent in summer season and 5-7 percent in winter season vegetation cover in Balochistan during the drought period. In addition to the direct impacts of this period of dry weather, significant increase in the number of tubewells in order to overcome the water deficiency during recent drought in the province resulted in over-abstraction of groundwater, particularly in the Pishin-Lora river basin. An average lowering of water table by 1-20 m per year in Pishin-Lora river basin triggered the process of identification of potential recharge sites in this heavily populated river basin. A methodology to delineate the potential groundwater recharge zones by means of geographical information systems and remotely sensed datasets was devised and spatial analyses were conducted using surface slope, drainage network, lithology and settlements in Pishin-Lora river basin. The results showed that about 50 percent of the basin had medium to high potential for recharging groundwater and the potential recharge areas were identified as the active zones for implementation of artificial recharge mechanisms for enhancement of groundwater recharge.