Study On Dynamic Water Balance And Regulation Ofbosten Lake In Xinjiang, China

The variation of Lake water table and its environmental change are unavoidable processes under climate change and human activities in arid regions. In this paper, The variations and driving forces of water table of Bosten Lake, the largest inland fresh water lake in China, were studied based on the observed hydrological, metrological and social-economic data of Bosten Lake during 1958~2012, and employed Gray correlation analysis as an effective methodology to discriminate potential contributions of natural and social-economic factors to table fluctuating of the Bosten lake. The results showed that:(1)Bosten lake experienced three phases of lake table fluctuating such as forepart falling, then rising and declining again with different driving weights over the past half century;(2)Results of Gray correlation analyses showed that, the variation of water level of Bosten Lake was caused mainly by the co-effects of the variations of natural factors such as flows into the lake, precipitation and temperature, and human factors such as the changes in farmland area, especially, the variations of flows into the lake was the main driving factor that effects the variation of water level. Because of Kaidu River runoff kept low flow state during 1958-1987, the water table of Bosten lake is slowly declined, the water table of Bosten Lake decreased from 1048.00 in 1958 to 1045.03 in 1987, the average water table was about 1047.20 m above sea level.The climate change is the most important factor to influencing to declining of the lake table during this period; Kaidu River runoff kept high flow state during 1988-2002,and surface water inflow to the Bosten lake increased.Contemporary,lake table raised significantly, the water table of Bosten Lake raised from 1045.21 in 1988 to 1048.60 in 2002, the average water table was about1046.80 m above sea level. During this period the influence of human activities on water table began enhanced, but the influence of natural factors still stronger than human activities on water table; surface water inflow into the Bosten lake decreased remarkably during 2003-2012, lake water table also declined remarkably, the water table of Bosten Lake decreased from 1048.55 m in 2003 to 1045.68 m in 2012. During this period the effects of human activities on water table are most remarkable;(3) For the encompassing period of 1958–2012 with over half century period, the main driver factors of water level variation transformed from climate change to social-economic development related human pressure.Over the past few decades, inland lakes unbalanced and their ecological environments were deteriorating due to combined effects of climate change and human activities. At present, to open out systematically the complex relationships and interact rules between factors of lake water balance are an important scientific issue to tackle. This paper studied largest inland fresh water lake—Bosten Lake based on system sciences and system dynamic modeling approach using metrological, hydrological and socio-economic data during 1983 to 2013. The results of dynamic water balance analysis, sensitivity analysis and scenario analysis demonstrate that:(1) the variation of Lake water level and its environmental change caused by coupling effect of climate changes and human activities. Among them, water table declining of Bosten Lake since decades is mainly due to proliferation of water demand in Konqi River area especially.(2) The order of most sensitive natural factors to lake water level variation are: surface water inflows > evaporation > surface water outflows; the most sensitive socio-economic factors to lake water level variation are: irrigation quota > irrigation area > industrial output > population.(3) The scenarios analysis in future 30 years indicate that: In order to maintain the water level at a proper level, the ecological environment well, and fulfill the sustainable development of socio-economic system simultaneous, following tasks have to done: control irrigation area and preventing enlarging again; popularization of water-saving technology in agriculture, adjusting industrial structure, effective use of water resources, optimizing water using proportions between the socio-economic and ecology.(4) Optimized regulation of Bosten Lake water balance analysis shouwed that guarantee the amount of surface water into the Bosten Lake, Lake and improve the water exchange rates,is the entire water resources and ecological environment of Bosten Lake basin the socio-economic evolution and development of the best choice.Instead,in the upper reaches of Bosten Lake,expansion of irrigated agriculture,may lead to the deterioration of the ecological environment of Bosten Lake,lakes to shrink or disappear altogether.Finally,in the Bosten Lake region will face water scarcity crisis.