|其他摘要||Water resources are indispensable material basis for human existence and social economic development. Boston Lake Basin is located in the hinterland of the Eurasian continent. The area has a typical inner-continental climate, featured by dry climate, low precipitation, strong evaporation, and shortage of water resources. The Bosten Lake Basin is the region with highest degree of development and water resource utilization. The deterioration of the ecological environment and the over exploitation of natural resources have resulted in vegetation degradation and eco-environment destruction. Due to the unreasonable allocation of water resources, the social and economic water consumption has occupied the ecological water requirement, which will cause excessive exploitation of groundwater and surface water. Agriculture is the major water consumption section, and the poor water management has gradually been recognized as one of the important reasons for water shortage. So it is necessary to carry out systemic analysis for water resources and to reveal the relationship between water resources and ecological environment. Based on the above analysis, we can formulate the scientific and reasonable mode for water utilization, and eventually realize the harmonious development of social economy and ecological environment.
Kaidu River is the main source of the China's largest inland freshwater lake-Bosten Lake. The runoff variation has great impacts on the improvement of ecological environment of Yanqi Basin and the Kongque River Basin. Based on theoretical study and practical experience of the successful irrigation water management at home and abroad, we analyzed the water management problems, and designed management system and regulation policy to facilitate the irrigation water resources. The results showed that:
(1) Based on the data of runoff, air temperature, and precipitation from 1958 to 2010, the effects of climate change on water resources in the Bosten Lake Basin were investigated. The long-term trends of hydroclimatic variables were studied by using both Mann-Kendall test and distributed-free cumulative sum (CUSUM) chart test. Results indicate that the mean annual air temperature increases significantly from 1958 to 2010. The annual precipitation exhibits an increasing trend, while the significance was less than temperature. Step changes are observed in 1996 in the mountain temperature and in 1985 in the plain air temperature. The temperature extremes show patterns consistent with warming, with a large proportion of stations showing statistically significant trends. Warming trends in indices derived from daily minimum temperature are of greater magnitudes than those from maximum temperature. In addition, evolutions of drought in the Bosten Lake Basin from 1958 to 2010 were analyzed based on the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), and the Palmer Drought Severity Index (PDSI). Differences between these drought indices were compared. For the entire geographical area of study, three contrasting periods were evident between 1958 and 2010 for both the SPI and SPEI. Wet conditions dominated during the period from 1987 to 2010, whereas persistent drought conditions occurred from 1960 to 1986. In addition a strong Siberian high-pressure and enhanced airflow from the Baikal Lake resulted in increased precipitation in the Bosten Lake Basin.
(2) Runoff variation showed different characteristics, and can be roughly divided into three stages, which decreased before 1986, increased between 1987-2003, and decreased after 2003. With the distance increase from the origin, the runoff showed human characteristics, namely, the inter-annual variation curve of volatility become more and more smooth. The precipitation and air temperature have significant impacted on runoff. Additionally, relationships between hydrological variables and seven selected teleconnection indices were analyzed. The hydrological processes in this region are affected by the area of Northern Hemisphere polar vortex (VPA) and the Tibetan Plateau High (XZH).
(3) Climate models have continued to be developed and improved since the IPCC AR4, and many models have been extended into Earth System models. Ensemble methods are used to explore the uncertainty in climate model simulations. The most common approach to characterize Multi-model Ensembles (MME) results is to calcu¬late the arithmetic mean of the individual model results.The future climate have been constructed using the CMIP5 model output available at the time of the AR5. This data set comprises 32/42/25/39 scenario experiments for RCP2.6/4.5/6.0/8.5 from 46 climate models. Future increase in air temperature is very likely in the Bosten lake basin. It is likely that the air temperature will increased by 1.5-4℃. For precipitation, there is no significant change under IPCC AR5. Based on the data of DEM, land use and soil data, we have constructed the SWAT model in Kaidu River Basin. The simulated results are in good agreement with the observed streamflow. In calibration period (1988-2000), the Nash–Sutcliffe coefficient is 0.91, the average relative error (REMS) is 1.6 %, and coefficient of determination (R2) 0.91. In the velidation period (2001-2010), the N-S coefficient, REMS and R2 are 0.87, 6.5% and 0.89, respectively, which have reached the standard of evaluation model. GCM ensemble mean data were coupled with the SWAT model to simulated future runoff. Under four emission scenarios, the runoff will increase with the spring runoff increase and summer runoff decrease.
(4) Using various methods, we calculated the domestic water demand (the norm method), livestock water demand (norm method), industrial water demand (multiple regression and Cobb Douglas production function), ecological water requirement (phreatic evaporation method), river water requirement (seven hydrology method), and agricultural water demand (crop coefficient approach). Combined with the water supply, the relatively reasonable water balance was given in this thesis. Due to the climate change and the increasing agricultural water demand year by year, water shortage has exacerbated in recent years, for example, in 2010, more than 8.56×108 m3 of water shortage were observed.
(5) At present, the water shoratge in Bosten Lake Basin are becoming more and more serious. We carried out the massive questionnaire survey and field investigation to study the agricultural water management, and pointed out the main existing problems for irrigation: 1) The engineering is not complete with a state of some disrepair; 2) Watershed management is divided by regional water management; 3) The irrigation area is actually underestimated; 4) The over exploitation of the groundwater caused water level dropped significantly; 5) The role of Water User Association (WUA) is very limited, some Water User Association (WUA) are difficult to maintain; 6) The structure of agricultural production is not reasonable. In the past, we usually adopt traditional techniques and engineerings to solve the water resource shortage. However, with the difficulty of increasing new construction, we must adopt some new ways to solve the water shortage. The strategy are as follows: Strengthening integrated management of River Basin; clearing the public right of soil and water resources;surveying the acturally cultivated land area; strengthening the strategy of "area determined by the water"; implementing the unified management of groundwater and surface water; Actively cultivating the farmer Water User Association (WUA).|