Impact on Water Resources
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Impact on Water Resources book
These above mentioned observed changes in rainfall pattern over the last 20 yr have disrupted the hydrological system of the watershed and contributed signifi cantly towards depletion of water resources in the headwater region. The hydrological imbalances have been observed in the forms of (i) decline in groundwater reserve, (ii) drying of natural springs, (iii) decrease in the water discharge in streams and springs (iv) drying of streams heads. Recent hydrological investigations carried out in Central Himalaya brought out the facts that the average groundwater storage level in the region was nearly 12 percent (Rawat 2009) as against the recommended norm of minimum 31 percent (Hewelet 1985). As in other parts of the Himalayan mountains, natural springs which are locally known as “Naula” or “Dharas” constitute the major source of drinking water in the region. These springs are fed by groundwater storage known as aquifers, and availability of water in aquifers depends on the rate and level of recharge of groundwater which in turn is regulated by a series of natural as well as anthropogenic factors, including the amount of rainfall and its intensity, slope, soil properties, geology, land use pattern etc. Obviously, the amount and intensity of rainfall is one of the most crucial factors determining groundwater recharge. The decreasing rainfall has played a very important role in drastically reducing the recharge of groundwater in the region. The present study revealed that out of the total of 107 springs of the Kosi headwater nearly 39 have completely dried up and more than 20 percent have become seasonal during the last 20 yr (Table 16.1). The studies carried out in other parts of Kumaon Himalaya revealed that 45-46 percent natural springs have dried up in the Gaula Catchment in district Nainital (Valdiya and Bartarya 1991), and Almora which is one of the oldest town’s in the state of Uttarakhand, 270 out of 360 natural spring have dried (Rawat 2009). As mentioned above, besides changes in rainfall pattern and erratic rainfall, several other factors,
particularly the land use changes, are also responsible for the drying up of springs in the region (Sharma et al. 2007).