Eco-environmental Indicators Of Groundwater In YUKA And Da Qaidam Basin In Qinghai Province And Its Assessment

Groundwater is an important ecological factor in arid and semiarid areas. The control effect of groundwater on ecological environment has been an important research of ecological hydrogeology. Since the inland basin topography occlusion, scarce rainfall, strong evaporation, water shortage is a major problem in arid and semi-arid areas of economic and social development constraints. In particular geographical background, act as an important part of water resources, groundwater is the main water supply source to maintain the growth of vegetation, is the geomorphic unit and vegetation species evolution leading factors, control vegetation growth state. At the same time, Inappropriate water depth range of geological problems are likely to cause environmental land salinization and desertification, threaten ecological stability and economic and social interests of human systems. Thus, coupling relationship between groundwater depth and vegetation ecosystems are reasonable theoretical basis to develop groundwater resources and ecological protection and reconstruction. Vegetation is an indicator of the ecological environment quality, closely related to the existence and nature of the vegetation evolution and groundwater, vadose zone. Integrated regional groundwater, vadose zone and vegetation on the ecological environment quality evaluation, as well as the relationship between groundwater depth and quality of the ecological environment, can provide guidance for human resources development and utilization of land. Remote sensing and GIS is an important tool for the study of modern hydrogeology, may obtain and analyze the correlation between large-scale groundwater and vegetation and ecological environment quality, data volume, time series of strong, broad spatial scales, is cheap, readily available and effective the method. YUKA and Da Qaidam basin located in the northern Qaidam Basin, the ecological environment is fragile, groundwater is the maintenance of the vegetation growth and the main source of human activity, it is also the seat of the national large-scale coal bases, Regional groundwater resources greatly affected by human activities. Study on the relationship between groundwater and vegetation species evolution and growth, and the evaluation of ecological environment quality and the depth interval of different underground water level is very necessary. This collection of remote sensing data, topographic map, the measurement system, including water level, groundwater sampling and soil sampling etc., The ecological environment factors on groundwater level and its relationship with the dominant vegetation and landform types, the groundwater ecological environment index, and through the spatial analysis and evaluation of groundwater quality of ecological environment, the ecological environment management and protection suggestion. The main research results are as follows:1,By1987,1994,2000,2006and2013TM8TM5images of remote sensing images, remote sensing and GIS spatial analysis technology based on the research, the regional ecological environment and groundwater dynamics, the past25years, showing the characteristics of annual groundwater stable and years periodic change regularly, ecological a benign development of foreland basin, oasis area, high vegetation coverage area increased more than150%.2,Different geomorphic unit vegetation index was significant difference. Swamp vegetation index approximate normal distribution, NDV10.4-0.8appears the highest frequency, the most vigorous growth of vegetation. The saline soil vegetation index<0.3has the highest frequency, the vegetation index is less than the swamp. The sandy land vegetation index is generally<0.1, sparse vegetation growth.3,The groundwater depth determines the distribution of desert and oasis, oasis distribution and soil salt content determine swamp meadow and salt meadow vegetation index difference, apart from the altitude and the groundwater depth is the dominant factor restricting water, also affected by soil salinity. The groundwater depth of<1m, with reed, sedge swamp vegetation index>0.3is the dominant species; groundwater depth is located in1-2of M, Achnatherum and Salicornia species was the dominant salt meadow vegetation index with groundwater depth and soil salinity increased; groundwater level the depth of m at2-3, and increased to reduce arris dominant species of tall shrubs vegetation index with the salt content of soil; groundwater depth of>3m, with the vegetation area Ceratoides dwarf shrub dominant species index with groundwater depth changes.4,According to the description of statistical analysis of field survey data, the index system of ecological environment in different terrain.(1) Underground water marshes buried depth of0-1meters, soil moisture,28%-50%value of33%, the soil salt content,0.1%-1.21%value of0.6%, soil organic matter,1.96%-8.19%value of4.92%, soil type is silty clay, the average elevation of3174-3210meters,3154meters, the slope of2.13degrees-11.04degrees, the average slope of5degrees, to the south.(2) Salt meadow area groundwater level depth of1-2meters, soil moisture,12.7%-21.15%value of20.68%, the soil salt content,0.16%-3.94%value of1.01%, soil organic matter,0.59%-3.18%value of1.58%, soil type is silt, elevation of3169-3225meters, average3199meters, the slope of2.57degrees-11.78degrees, the average slope of4.84degrees, to the south the main. (3) Underground water depth of2-3meters tall shrubs, soil moisture,11.7%-15.9%value of13.8%, the soil salt content,0.12%-0.89%value of0.53%, soil organic matter,0.96%-5.69%value of2.6%, soil type is silt, elevation of3153-3217meters, average3184meters, the slope of3.01degrees-12.3degrees, the average slope of5.6degrees, to the south.(4) The underground water level low shrubs depth greater than3meters, the soil moisture content,0.96%-9.2%value of5.52%, the soil salt content,0.02%-2.86%value of0.55%, soil organic matter,0.41%-5.81%value of1.66%, soil type is sandy gravel, elevation of3175-3304meters, average3229meters, the slope of1.43degrees-13.87degrees, the average slope of8.44degrees, to the south the main.(5) Deep buried underground water quality control of ecological environment. The groundwater depth of<2m, the good and the general quality of ecological environment, groundwater mineralization and soil salinity is the main factor affecting the water depth range of ecological environment quality, and sensitive to groundwater level fluctuations, the fragile ecological environment; water depth is2-3for m, the ecological environment quality in general and well, this combination of water and salt groundwater surface soil depth range to meet the growth of vegetation, land suitable for human use; water depth is3-4for m, the ecological environment quality was significantly decreased; when the water depth of>4m, the water depth interval surface80%of the total area of surface quality of ecological environment the poor, the deterioration of the ecological environment.