| Increasing socio-economic activities and the rapid growth of population have greatly increased water demand in recent years, and the contradiction between supply and demand of water resources has become increasingly prominent. Climate change is predicted to increase stress on freshwater systems around the world especially in the inland arid river basin. The study of water balance between supply and demand under climate change has important theoretic and realistic means both to the rational utilization of water resources and the realization of sustainable development of society and economy.The primary objective of this thesis is to study the impact of climate change on water balance between supply and demand in the Hutubi River Basin(HRB). The changing trend and characteristics of climate and runoff, and response of runoff on climate change in the last 50 years were analyzed and discussed in this thesis. Water resources component and transformation were investigated by water isotope and chemistry. Based on the evaporation and water demand models developed, the characteristics of water use during the last 20 years were analyzed, and water balance between supply and demand were analyzed under different hydrologic year. At last, a framework of the most strict water resources management modes was recommended, and some countermeasures and proposals were also provided in this thesis. The main results of this thesis are as follows:(1) In the last 50 years, there were statistically significant increasing trends in annual average temperature, annual precipitation and runoff in HRB. We analyzed trends using the Mann-Kendall(MK) test. Our results indicated that there was a notable increasing trend in annual temperature of 0.35 °C/decade(P<0.05) and step change points in 1995(P<0.01). Annual precipitation showed a significant rising trend(P<0.001) at a rate of 13.29 mm/decade and step change points in 1992(P<0.05). Similarly, annual runoff showed a significant rising trend(P<0.001) at a rate of 0.13 ×108m3/decade and step change points in 1990(P<0.05). The temperature of the desert and oasis area was more sensitive to the response of the global climate change, but that the precipitation on the mountain area. Climate change could have important effects on the regional water resources.(2)Annual runoff in the HRB has periodically fluctuated during the period of 1956-2011 through Mann–Kendall test and PRDCC, an abrupt change point in annual runoff was identified in the HRB, which occurred in the years between 1986 dividing the long-term hydrologic series into a natural period(1956 – 1986) and a climate and man-induced period(1987– 2011). The impact of climate change on runoff change is from74.21% to 83.07%, and the impact of human activities on runoff change is from16.93% to 25.79%. This study distinguishes the effect of climate change and human activities on runoff in HRB, revealing an increasing threat of water resource to the arid ecosystem in the arid regions. There are various uncertainties in the hydrologic sensitivity analysis method in separating the effects of climate change and human activities on the runoff which may have arisen from the input data and model parameters.The function of the hydrologic sensitivity analysis method is based on the data for a long-term period of natural runoff without the effects of human activities, uncertainty of the model parameter can also affect the results.(3) Through the water stable isotope composition measurement, we investigate the temporal and spatial characteristics in stable isotope δ18O and δD of surface water, groundwater and meltwater in HRB. The δD and δ18O values of surface water samples were-66.66‰ and-9.94‰, the groundwater samples were-69.82‰ and-10.23‰,and the meltwater samples were-150.79‰ and-19.42‰, respectively. Groundwater chemical evolution is mainly controlled by rock dominance and the evaporationcrystallization process, with the surface water and ground water types mainly as the SO42-—HCO3-—Na+. Comparing the stream water line with the surface water /groundwater line and local meteorological water line of Urumqi, it is found that the contribution of precipitation to surface water in stream runoff is the main source, whereas the surface water is the main source of groundwater. Groundwater is mainly drainage of surface runoff in the river.(4) Based on the Fu’s analytical solutions to Budyko’s coupled water and energy balance hypothesis, this study is aimed to develop a coupled water-energy balances method for watershed evapotranspiration. This enables one to estimate the parameter from catchment characteristics with the relative infiltration capacity, relative soil water storage, the average slope and drainage area. By stepwise regression analysis, a semi-empirical formula for the parameter in terms of the dimensionless landscape parameters is proposed. Applications of Fu’s equation together with the parameter estimated by this empirical formula have predicted the annual evaporation in HRB.(5) Between 1992 and 2012, there was a significant upward trend in total annual agricultural, industrial and domestic water use in HRB. The presented industrial and domestic water use models can be successfully applied for estimating industrial and domestic water use in HRB. The total agricultural, industrial and domestic water use in 2012 in HRB were 6.76×108m3、0.11×108 m3 and 0.06×108m3, respectively. Water supply in HRB was inadequate to meet the water requirements except some wet years in the past and current years. Thus, socio-economic system had to transfer water from natural ecosystems in order to lessen their economic loss. Consequently, ecological problems emerged in the basin.(6) A framework of the most strict water resources management modes in the inland arid river basin was recommended, and some countermeasures and proposals were also provided in this thesis. Some feasible countermeasures and proposals were provided to solve the problem of water shortage, and realize sustainable water utilization and sustainable development of society and economy. |
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