The Study On Temporal And Spatial Variation Of Groundwater Depth Of Western Jilin Province

Groundwater is an important information carrier, in the dynamic elements of groundwater, the groundwater depth directly reflects the distance between the top surface of the aquifer and the ground surface in a certain period of time, a direct bearing on the issue of soil salinization and growth and development conditions of the surface vegetation. Especially in arid areas, due to the lack of precipitation , arid ecosystem have great dependence on groundwater,if the groundwater depth is too shallow somewhere then the soil salinization occur easily, if groundwater depth is too deep, the surface vegetation degradation and soil desertification will occur due to lack of soil moisture. Groundwater depth play a decisive role in surface vegetation and the local ecological environment in arid area. West of Jilin Province is a typical arid and semi-arid regions, in recent years, changes in climatic conditions lead to the local people's exploitation strength of groundwater resources increase yearly. Under the combined action of natural and man-made factors, a series of ecological problems become more outstanding, such as the fragile ecological environment,surface vegetation degradation, desertification, and salinization of soil and so on, which have become the main restrictive factors for production and life of local people and the sustained and healthy development of the regional economy. In response to these environmental problems which urgent need to alleviate, and comprehensive consideration the technical means, based on previous research, this paper selected groundwater depth to research, and study the characteristics of temporal and spatial variationin of groundwater depth in West Jilin Province for many years.First of all, the author collected and got observation data of groundwater depth for 1987,1993,2000,2004,2006 five years in western of jilin province. Making use of above data and using Kriging interpolation method. Drew and got the spatial distribution maps of groundwater depth in the study area for the above-mentioned five years by the application of ArcGIS software, provide an intuitive expression for the characteristics of temporal and spatial distribution and change law of groundwater depth of the western Jilin Province from 1987 to 2006 in the past 20 years. Make e statistical process to the distribution area occupied by different groundwater depth distribution, and make quantitative analysis to the characteristics of spatial distribution of groundwater depth . In order to make the inter-annual changes characteristics analysis and expression of the western Jilin groundwater depth more detailed, limited by data, this paper select the number of observation wells as representative points, and finishing the long time series groundwater depth observation data of the selected wells, and rendering inter-annual changes curve of groundwater depth by using statistical software. By the above curve map, this paper expressed the characteristics of inter-annual variability of groundwater depth in West Jilin Province for many years. Based on the above-mentioned analysis results, the author study and explore the main influence factors of the changes in groundwater depth.Secondly, in order to make the analysis and research more intuitive, based on the two-dimensional spatial analysis ,this paper develop and apply three-dimensional expansion module ArcScene, and realized the three-dimensional visualization expression of the spatial distribution on groundwater depth of the study area.Finally, forecast for future tendency of groundwater depth in study area with the application of groundwater flow numerical simulation model. Combined with the changes characteristic on natural environment and activities of local people in the study area for many years, this paper explored the influence degree of the natural and man-made factors on the temporal and spatial distribution of groundwater depth changes. Basis for the dynamic change law and the main impact factors and the impact on the ecological environment of groundwater depth in Western of Jilin Province, this paper put forward the rationalization proposals for the sustainable exploitation and utilization of groundwater resources.Through the above studies, from time view point, the general changes characteristics of groundwater depth over the past 20 years in the study area obtained from the observation data of above five years; the regional average groundwater depth from 4.7 meter in 1987 increased to 6.92 meter in 2006. The annual average increase rate of groundwater depth showed a go-up tendency in the years from 1987 to 2004, since the 0.133m/a increased to 0.153m/a. it become a little stable from 2004 to 2006 as 0.085m/a. By analyzed and summarized, because of natural climate changes, the reduction of precipitation, groundwater depth generally show a downward trend in West Jilin Province over the past 20 years, the amplitude reduction increases gradually from the Northwest Piedmont Plain tilted to the south-east High Plains. As a result of population growth, agricultural production activity has strengthened, with the decrease in precipitation, human exploitation for grondwater resource have increased substantially. The amplitude reduction near the center of administrative division greater obviously than it in other area, and the cone of depression have engendered in local area .