Xianyang City Groundwater Dynamic Evolution And Ecological Effects

Xianyang City in the central clearance as a sub-humid and semi-arid region of the transition, the edge of the monsoon zone, but also in economically developed areas of the Guanzhong area, groundwater plays a vital role in the region's economic development,in study of evolution laws of groundwater and the impact on the ecological environment, it is important practical significance of sustainable development of groundwater resources in Guanzhong area.Based on the Xianyang City, the dynamic changes of groundwater sub-regional statistical analysis, summing up the evolution law of groundwater in different parts, combined with multiple regression analysis in Xianyang City, equation set up to discuss the impact of different elements to the water table, the main conclusions were as follows:(1) By the relevance of climate analysis in 20 years of Xianyang City, we found that correlation between precipitation and temperature divided broadly into three stages: the first stage of cold-wet phase, from approximately 1986-1992, the temperature was clear downward trend, and precipitation showed an upward trend; the second stage of the process of warming and drying: From 1993-2002, the temperature was increased overall, but less precipitation. Warm phase of the third stage: From 2003-2006, the temperature remained high temperature, and precipitation over the previous two phases was significantly increased.(2)The use of the water table to the monthly values in 20 years in Xianyang city, respectively, analysis the dynamic changes of the water table for three different landforms showed that:â‘ terrace area of Wei He river: ground water level at 20 years was significant linear downward trend, urban concentration , population density, production, in domestic water increase faster year-on-year, the water table in this area are the direct cause of decline.â‘¡Loess plateau area of Taiwan: Overall fluctuations drop of the ground water level is main trend in 20 years, land-use of the area from wheat, corn into fruit, vegetable producing areas , require irrigation water, new wells eyes dramatically increased in near 20 years, and irrigation methods in this area are traditional, extensive still, mainly flood irrigation, so over-exploitation of groundwater, resulting in declining of groundwater levels.â‘¢Loess hilly and gully area: the groundwater table Change can be divided into two phases :In the frist phase for 1986-1988, the water table is rise slowly,it is relative consistency between groundwater and atmospheric precipitation ,the precipitation is a major factor in rising groundwater. In the second phase for 1988-2006, the groundwater decreased clearly, the per capita water consumption increased rapidly, along with the increase in population in this area quickly, are also important factors in the decline.(3)By interannual regression analysis of the groundwater level in Xianyang City, we can see that the precipitation are important groundwater recharge source, and evaporation, irrigation area and the production and living water is the main reason for lowering the water level. As can be seen from the equation, evaporation to the water table is less than the impact of irrigated area and production, domestic use. From the weight on that the amount of irrigation water seriously affect table changes, but in Xianyang City, the irrigated area to statistics in 20 years show that the irrigated area was decreased, irrigation water be reduced, and therefore irrigated area of Xianyang City contribution rate of decline in groundwater level is not. Evidently, in addition to irrigation, the increase in production and living water become a major factor in declining groundwater levels.(4) Through the seasonal variation of groundwater level and precipitation, evaporation, production and living water, and irrigation capacity to do multiple regression analysis found that: changes of the water table in Xianyang City, all the impact of seasonal factors are not the same as.â‘ In spring, groundwater level is mainly affected by the common effects of the volume of evaporation and irrigation ,show the smaller drop.â‘¡In summer, decline in groundwater level is mainly affected by irrigation water and water of production and living large, evaporation is also an important factor in the decline in groundwater.â‘¢In fall ,water table decline is mainly affected by irrigation water and water of production and living large, have a larger decrease.â‘£In winter, groundwater level decline is mainly affected by the production and living water and irrigation water larger and decrease in the minimum for the four seasons.Each season from the impact of declining groundwater levels , production and living water and irrigation water man-made factors such as the impact of groundwater decline are the main factors.(5) Declining of groundwater level will cause a series of eco-environmental problems ,they are: the depletion of water resources; land subsidence, the formation of the funnel.; the formation of cracks; deterioration of groundwater quality.(6) In accordance with the characteristics of groundwater level change in Xianyang City and ecological problems propose some countermeasures of sustainable use of groundwater.