Coupling Relationship Between Hydrological Processes And Eco-environment Evolvement

Due to special climatic condition and natural environment in northwestern arid regions, how to rationalutilize water resources is one of the basic issues to develop the society and economy and protect ecologicalenvironment. Thus, harmonization between water resources utilization and eco-environmental protection isone of the key factors realizing sustainable development in Tarim River Basin. This article analyzes thecharacteristics, trends and causes of water resources variations in Tarim river; the time series analysis andnonparametric test are adopted to predict the trends and periodicity of runoff changes, and to indicate thelinks between runoff, temperature and precipitation. The correlation between vegetation NDVI and waterresources utilization in the mainstream of Tarim River is also analyzed. The method of investigating naturalvegetation samples is used to determine the recharge between the groundwater and soil moisture, and tostudy variation of natural vegetation growth. Meanwhile, the vegetation physical indices are measured toanalyze the drought-resistant intensity of natural vegetation in different groundwater level. Taken the lowerreaches of Tarim River as an example, this paper shows the processes, phenomena and causes of theeco-environment degeneration. In terms of resuming hydrological processes through ecological waterconveyances, eco-environmental changes mainly are discussed including water resources consumption ofwatercourse, the characteristics of stream flows and water lost, groundwater level variations in time andspace, the natural vegetation responses to water conveyances, the water conveyances influence on landdesertification, the groundwater movement after water conveyances and GIS analysis of the naturalvegetation growth before and after water conveyances. The eco-environmental restoration and irrationalutilization of water resources are the core issues to harness and manage Tarim River Basin in future. Themain objective of this study was to explore the coupling relationship between hydrological processes andecological environment in the two different aspects through a case study of Tarim River. Some conclusionsare draw as followings: 1)View from the hydrological processes of Tarim river basin in recent 50 years,under the influence of the global climate, the temperature and precipitation of Tarim river basin are bothincreasing in a certain extent, which causes increased runoff of the headstreams especially in 1994-2003;2)Although water coming from the headstreams is increasing in recent years, water flowing to themainstream only increases by 0.9985×108m3/a,which is 3% of the total increased water volume. Theresult reveals that the increasing tendency of water consumption in the headstreams is farther higher thanwater volume of forming runoff .Analyzed correlativity amongst water resources consumption, populationand farmlands, the increase of water resources consumption is a direct result from the increased populationand farmland areas; 3) In order to approve the causes of runoff increasing, the non-parametric test isadopted to test the change trend of temperature, precipitation and runoff of the headstreams. The resultsreveal that the relationship between the increase of runoff and temperature is stronger than that betweenrunoff and precipitation; 4) Changes to groundwater level changes the physical indices of natural vegetation,namely when the groundwater level is under a certain level, PRO and ABA content of natural vegetationobviously increase. That identifies that the drought-resistant intensity of natural vegetation increases withthe decrement of groundwater level; 5) By GIS analysis of the natural vegetation growth and stream flow,there are a stronger relationship between vegetation NDVI and stream flow of the different sections inTarim River; 6) When resuming stream flow along the lower river after water conveyances, thegroundwater level lifts, natural vegetation has obvious response. Those changes show that waterconveyance can restore extreme -degraded environment and also verify the cou...