Flow Trends in River Chitral due to Different Scenarios of Glaciated Extent

摘要

Glaciers are considerably important machinery which is necessary to keep the equilibrium of the earth. The rapid boost in the mean temperatures of the globe and abnormal precipitations are the direct warnings for glaciers to survive. Mostly the perennial rivers of the world emerge from glaciers. In an agricultural country like Pakistan the existence of the glaciers is of prime importance. The major river of the country originates from the Himalayan and Karakorum glaciated mountains. River Indus is a vital example. Moreover the mega and world renowned Tarbela dam also exists on the same river. This can be surly concluded that the future of a country is directly associated with the flows available in the rivers and hence the existence of glaciers. The rapid disintegration of the glaciers has been reported throughout the world which is obviously not a healthy sign. Therefore, a careful study is required to estimate the variations of the flows with the receding glaciers. As a case study, Chitral watershed in Pakistan has been selected. The UBC watershed model has been used to forecast the flows. The model was calibrated for the daily flows observed in 2009 at Chitral stream gauging station. The percentage contributions to the total annual flow were simulated as 23%, 31%, 1% and 45% due to glacier melt, snow melt, rain-fall runoff and groundwater, respectively for year 2009. Model results were validated for the flows of year 2006 and 2007. The further analysis was performed by assuming reduction in glaciated areas and considering the climatological conditions same as observed in year 2009. The model results show that a significant decrease in the flows of Chitral River appears due to the assumed reduction of glaciated extent.