Research Of Groundwater Control Based On The Inland Arid Region Ecological Security

For the inland arid region, the oasis ecological security should include the irrigation of land security, the safety of natural vegetation inside and outside irrigation and water resources safety starting from its natural attributes. To ensure the safety of irrigated land is to make the farmland salinization from harm. Ensureing the safety of natural vegetation is to make the irrigation of natural vegetation from water stress in the maintenance of normal growth. To ensure safety of the oasis is to ensure that the normal of the rivers, lakes and ecological functions of groundwater environment within irrigation. Soil and water resources in irrigated oasis development must take into account water, soil and vegetation bearing threshold, specific performance threshold for the groundwater table. Therefore, the inland groundwater level of ecological security is defined as to sustain the normal growth of an oasis of natural vegetation, to ensure that does not occur Oasis land salinization and desertification, environmental problems. The depth of groundwater table under the oasis ecological security of irrigation can be a specific value, can also be a range. In this interval, the oasis irrigation system has the highest ecological stability and healthy development of the adaptive cycle, deviation from the equilibrium position after a certain period of time can automatically recover, the irrigation ecological environment is in a safe state. Over this range, the stabilityof irrigated environment is destructed, and the stability of oasis is threatened.The study area Yanqi Basin is located in the hinterland of Xinjiang, Since the last century since the fifties, because of its large-scale water and soil resources develop, resulting in a larger regional hydrological changes of ecological environment. In this paper, master in the hydrological and ecological problems in Yanqi Basin, through analysis and summary the study area groundwater, salinity, land use, soil salinization evolution in the past 50 years, focus on Pattern of groundwater and salt in response to land use and soil salinization changes, and On this basis, discussed from various angles of reasonable level based on range of ecological security in oasis. To determine the reasonable groundwater control measures under different conditions, in shallow groundwater depth irrigation from low reaches of Kaidu River, we establish a typical test area for groundwater control. Through the monitoring for water balance in this region, we established groundwater numerical model of the typical test area based on Modflow, and analysis the water balance changes from each control programs which based on ecological security stage, through the program selective preference gives the optimal operational optimization of water table control mode.Based on the optimal control model of groundwater from the typical test area, we given the primary regulatory control measures combined with groundwater control division research, and rely on groundwater numerical simulation model in Yanqi basin, to analyze the changes in water use after groundwater control.The main results are as follows:evapotranspiration in 2008, and use its spatial distribution pattern as the groundwater pattern of the spatial distribution of evapotranspiration, and substitute it to the groundwater numerical model, in order to facilitate further improve the model's simulation accuracy.(1) Optimize by spatial interpolation method, I think that using a natural neighbor interpolation method to be possible to gain the optimum ground water buried depth and the spatial distribution of dissolved solids. Combined with a variety of GIS methods, I has carried on the analysis to ground water buried depth and the spatial distribution of dissolved solids in 50years, and gained their evolution rule in 50 years.(2) Based on Visual interpretation for each period remote sensing data in Yanqi Basin, combined with spatial analysis methods to study the area changes in land use for 50 years; according to different periods of Yanqi survey data of soil salinization, analysis the study area salinization trends.(3) Using hyperspectral remote sensing inversion technology, combined with ground truth spectra and the sample analysis, we got the sensitive band for soil salinity in study area, Based on this data, we build the model for Soil salinization remote retrieve based on MODIS date; using remote sensing quantitative inversion techniques, through build the Sebal model which Based on the principle of surface energy balance, inversion of the monthly surface(4) By analyzing the response of groundwater, salinity to land use and Soil salinization changes in Yanqi Basin, we give the Ecological security groundwater table from multiple perspectives, and proposed the maintenance of ecological safety groundwater level is 2-3.5m in Yanqi Basin.(5) Established the typical groundwater control area in the study area, and through monitor the surface water, groundwater, soil water in test area, we establishment of the typical groundwater numerical model based on Modflow. According to the model, simulate each groundwater control programs, and by optimization programs the best control mode in shallow groundwater irrigation is given.(6) Use 2008 as the current year, established the numerical model of groundwater for Yanqi basin, based on the groundwater control mode from the typical test area, through the regulation of Yanqi groundwater district, study out the each district's appropriate control measures, and simulate the result for groundwater control program, access to the water balance and groundwater level after the groundwater control is implement.