| Based on the geology and hydrogeology investigation and the Dynamic monitoring data of groundwater level for many years in Jilin province part of Songnen Plain, combined with 3S technology, the spatial distribution map of buried depth of groundwater was drew using the GIS software. The groundwater dynamic types were determined based on temporal and spatial dynamic analysis of groundwater. The groundwater dynamic was forecasted by time series analysis method and its influence factors of were analyzed. The natural groundwater resources, available withdrawal of groundwater and groundwater storage were calculated, andthe distribution characteristics and exploitation potential of groundwater resources was analyzed. Based on the environmental geological problems in the exploitation of groundwater in the study area, the Countermeasures for the sustainable utilization and protection of groundwater are discussed. The conclusions were as follows:(1) Combined field investigation and 3S technologies, the temporal and spatial dynamic characteristics of groundwater level of Quaternaryporephreatic water, Quaternary confined water and Tertiary pore-fissure water were analyzed. Results showed: for Quaternaryporephreatic water, the buried depth of groundwater was mainly 10-20 m in eastern high plain, and it was mainly 3-10 m and 5-10 m in center low plain and alluvial fan, respectively. The buried depth of groundwater was mainly 5-10 m for Quaternary confined water. The buried depth of Tertiary pore-fissure water mainly ranged from 10 m to 20 m.(2) The majority of the annual dynamics of groundwater depth showed a downward trend, and the decline range had greater relationship with local exploitation and aquifer characteristics. The variation of groundwater level within the year showed that in many areas, the groundwater level in flood period increased by 0.13-5.11 m than drought period, of which the fracture pore confined water level increased by 0.21-3.80 m. Due to large amount of exploitation, the groundwater level showed a downward trend in some areas with decrease of 0.1-5.29 m.The groundwater dynamic types were determined according to groundwater level analysis. For the phreatic water, it was rainfall infiltration-evaporation type in alluvial lacustrine low plain area, rainfall infiltration- runoff type in high plain sand and gravel platform, runoff type in alluvial fan, rainfall infiltration- runoff- evaporation type in alluvial plain high sinuolate, rainfall infiltration-runoff – evaporation- runoff typein alluvial valley plain. For the confined water, it was runoff type outside the area of the groundwater funnel, and it was runoff-exploitation type inside the area of the groundwater funnel.(3)The groundwater dynamics was predicted using time series analysis model. After determining the periodic component, the random component and the precision test of the model, the suitable prediction model was obtained.Through the trend analysis, the groundwater level of the area was mainly dominated by the descending of groundwater level, especially in the serious over exploitation areas, the descending range was larger. Period analysis showed that the dynamic change of groundwater level was 1 year and 3 years.In the next few years, the groundwater level will change significantly with the seasons, and the descend trend is the main trend.There are many factors affecting groundwater in Songnen Plain, including the human and natural factors.Among them, human factors have great influence on the dynamics of groundwater. In recent years, with the water consumption of industrial and agricultural and residents increasing,the regional water level is decreased in some areas.In addition, the construction of water conservancy project, channel water filling and irrigation makes the local groundwater level increase, which also influenced the dynamic changes of the groundwater level.(4) Based on the hydro-geological model of the study area, the groundwater natural resources, available withdrawal groundwater resources and groundwater storage were calculated and their distribution characteristics were analyzed. Results showed: years average recharge and discharge of groundwater was 564659.97×104m3/a and563542.01×104m3/a, respectively. The years balance of groundwater was 1117.96×104m3/a. Total amount of groundwater exploitation resources was 395685.39×104m3/a,of which the amount of phreatic water exploitation was 276804.73×104m3/a,and the amount of confined water 276804.73×104m3/a. The storage of Quaternaryporephreatic water and confined water was 974.40×108m3and 571.14×108m3, respectively. The storage of Taikang confined water and Daan confined water was 1697.52×108m3and 1872.96×108m3,respectively. The total storage of groundwater in the study area was 5116.02×108m3.(5) Based on the groundwater resources assessment, combined with the analysis of groundwater resources development and utilization status of the history, the groundwater exploitation potential was evaluated. Results indicated that groundwater development potential index(P) of Changchun city is 0.62-1.13, and the over exploitation amount was 3.67×108m3/a. the Groundwater development potential index of Nong'an,Yushu and Dehui city was 0.76, 0.72 and 0.62,respectively, which were all over exploited. There is great exploitation potential in Songyuan city with groundwater development potential index(P) is 2.4. The Baicheng city is a potential exploitation area with groundwater development potential index(P) is 1.34, and it can expand exploitation by 3.94×108m3/a.The average groundwater development potential index(P) of the whole study area is 1.24, and it can expand exploitation by 7.51×108m3/a.(6) According to the problems existing in the research area and the exploitation potential, the direction of water supply should be adjusted, and the exploitation of groundwater in over-developed area should be reduced. The groundwater exploitation layout should be rational controlled. Improving the construction of emergency water supply system and establishing the management mode of the scientific utilization of groundwater resources were necessary to ensure the sustainable utilization of water resources. |
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