| Lake wetland is the primary category of wetland in the dry area, which plays the key role in maintaining the stability of "mountain-oasis-desert-lake" system.Ebinur lake wetland is located in the unique geography and ecosystem area, whose degradation will severally threaten the ecosystem safety of the northern Tianshan mountain slope economic zone.Over the past 60 years, under the influences of natural backgrounds and human activities,Ebinur lake wetland area has declined quickly, whose bald bottom becomes one of four sandstorms sources and makes it become the second ecosystem degradation area next to lower reaches of Tarim River in Xinjiang. This thesis selects Ebinur lake wetland, the largest lake wetland in Xinjiang, as the study area and chooses the ecological vulnerability present situation, typical eco-features of degradation process and its driving system as study object. It is under the guidance of modern geography, ecology and adopts field research, experiment, remote sensing techniques, model construction methods to analyze and discuss Ebinur lake's eco-elements space differences, such as water, earth, plants; meanwhile it analyses the features of wetland area,eco-factors like water, earth and plants as well as the transformation between wetland and non-wetland in the wetland degradation process.It applies many methods and math model,together with the collected water, climate, social economic files to construct the model of Ebinur lake wetland degradation process. Furthermore, it predicts the degradation tendency in accordance with this model.The thesis main contents are as follows:(1)Ebinur lake wetland has been decreasing dramatically in the recent 60 years.The decrease of wetland results in the change of bald bottom becoming the origin of sand and the wetland ecosystem and lake surrounding desert ecosystem deteriorate change has greatly harmed the creatures diversity.(2)The big space differences of Ebinur lake present degradation situation are obvious. The space differences of Physical and Chemical property on different types of water show a characteristic as follows:the biggest one is shallow underground water and the smallest is spring water. Among these the water mineralized degree shows the discipline of underground water-lake water-deep underground water-spring water. The potassium containing amount space difference is small, but the ammonia-nitrogen containing amount space difference is big. The earth of Ebinur Lake wetland contains lower water amount, and shows the discipline of surrounding wetland-river flowing into lake mouth-spring spreading area-desert. The Ebinur lake's surrounding earth's pH value space spreading characteristics are:north-south, east-west, and northwest-southeast. Ebinur Lake wetland earth contains comparatively low amount of organic matter, and its space difference shows the characteristic of Aqiksu River surrounding earth organic matter containing amount-lake surrounding organic matter amount. Different plants'sub-creatures show obvious varieties in Ebinur lake wetland, and have apparent space difference. Two sorts of creatures' variety Margalef and Gleason show common tendency in the study area. The eco-advantage degree shows clear differences.(3)Ebinur Lake wetland's degradation process presents in the following fields: the wetland area change, eco-factors change, such as water, earth and plants and transformation between wetland and non-wetland. Ebinur lake wetland area varies greatly in one year. The largest area time is between March and May, while the smallest July and October. Over the past 60 years the annual change can be divided three stages:increasingly degradation, relatively stable and slowly dry. The water mineralizing degree shows the tendency of increasingly rise, gradually decrease and slowly rise. In recent 30 years typical area's earth nutrition change shows characteristic of organic matter amount decrease, earth potassium element decrease rapidly. The lake surrounding plants changes in the direction of wet growth, neutral growth, super dry growth, salty growth and sandy growth. In the 15 years of 1990, wetland and non-wetland change process shows the characteristic of lake wetland grows constantly, river wetland grows first and decreases then, smash wetland decreases first and then increase.(4)The results of parameter and non-parameter statistic test show that the yearly average temperature and in different seasons has an increasing trend. Yearly mean rainfall increasing too.But yearly evaporate has a decline trend. The streamflow of five main rivers in Ebinur lake basin shows different level increasing trend.The Hurst index analysis presents the streamflow which flows into Ebinur lake will keep increasing trend in future.The period analysis reveals that the change period of streamflow which flows into Ebinur lake is 21 years, while the streamflow in Bortala River is 21 years. The change period of Jing River is 18 years.In addition, the change period of Gurtu River is 18 years. Both of Kuitun and Sikeshu River change periods are 8 years.The hydrological forecasting results by trend superposition model and mean gengerating function model presents the same change trend with Hurst analysis and shows the streamflow in the river which flows into Ebinur lake will increasing in the next 10 years.(5)Using the temperature and rainfall materials from 1960 to 2007 from five weather station in Ebinur lake basin, the author concludes that the key to climate change is the temperature change. The abrupt change year of yearly average temperature,mean temperature in summer and autumn is 1996 and the year of streamflow which flow into Ebinur lake is 1997. Because of this, the increase in stremflow under climate change is 14.92% during 1997-2007. Relationship between the main climate factor and the area of Ebinur lake wetland shows that the two most important climate factor which influence the Ebinur lake wetland are the changing of summer and winter temperature in Ebinur lake basin. Futhermore,temperature change causes the wetland degradation by means of changing the mountain streamflow supply force.(6)Human activity causes the change of lake wetland by means of changing agriculture producing scale. The author founds out that agriculture water usage is the main human activity water consuming form according to the analysis of human activities characteristics between 1950 and 1990. The author analyses the land use and plants covering and finds out that apparent characteristic of land use and plants covering transformation in this period is that farming land increasing tendency and condition Pt index is 0.8262,which shows the land use and plants covering in Ebinur Lake is in extreme unbalanced condition. The author selects economic factors such as total area of farming, economic crop, a food crop to find which factors are the decision to area of lake wetland. The results is area of farming especially the area of economic crop.(7)Through the analysis of natural backgrounds and human activities driving factors, it is concluded that the key factor to the degradation of Ebinur wetland is the streamflow and farming area. According to farming area change rate, streamflow change rate, lake wetland area change rate, the author forms the model: which reflects wetland degradation driving factor. According to historical data, the author analyzes the farming area change rate, streamflow change rate and lake area change rate and concludes that it is abnormal development stage between 1977 and 1994 and normal development stage between 1995 and 2005.In accordance with overall conclusion, together with computer parameter model result, the author chooses stable development, constant reclamation and appropriate reclamation and predicts the wetland area in the following 9 years. If the reclamation could be kept stable,the lake area can be 231.39km2-414.39km2,while if constant reclamation continues, the lake will disappear completely in 2014.However, the appreciate reclamation will keep the lake area between 501.94km2-543.24km2.
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