| Liulin sping is the biggest spring in Luliang city, Shanxi province. The karstic groundwater in Liulin spring area is the important water supply sources for regional life and production. However, along with the accelerated human activities, the flow of the Liulin spring has been declining recently and the water quality of the karstic groundwater in local areas has exceeded III standards, it will be threat to water supply of life and production in some degree, therefore, to study the karst water system has the great significance for water safety, ecological environment balance, steady and rapid development of economic and comprehensive social progress.The geologic structure and lithologic conditions of Liulin spring area were analyzed systematically in this paper based on the collection of pre-existing investigation data, experiment data and research results; According to hydrogeological profile combined with the theoretical analysis, the properties of the Liulin spring area boundary were determined and the boundary were scientifically delineated simultaneity; The storage conditions, cycling condition, chemical characteristics, pollution status and dynamic characteristics of the karst groundwater were discussed as well.By using the grey slope similarity incidence analysis model, combined with hydrogeological condition in Liulin spring area, the time-lag between the precipitation and the discharge is analyzed. The result shows that the time-lag is different from different recharge zone; The discharge is affected by precipitation within a year in I zone, while between1-2years in II zone,4-5years in III zone and8-9years in IV zone. The precipitation from I to IV zone affected the current discharge together. The influence mechanism which precipitation, river leakage and karst water mining affected on spring flux attenuation was described respectively, meanwhile, the dominant factor for spring discharge attenuation in different period was analyzed by the contrastive analysis of weighted precipitation series P(t), spring flow series Q(t) and mining series E(t). The result shows that the spring flux attenuation process was divided into four periods. Decreasing precipitation affected the spring discharge more between1983-1989while the spring flow attenuation was mainly affected by increasing karst water mining between1990-1999, decreasing precipitation and increasing karst water mining affected the spring discharge together between2000-2005, increasing karst water mining played a desive role for spring flux between2006-2009.The Partial Least Squares Regression (PLS) model is developed to simulate and predict the spring discharge, the model was revised according to the physical significance simultaneously. The result showed that the average error of the modified PLS model was0.05m3/s and average residual percentage was2.05%for fitting stage, and for checking stage that is0.12m3/s and5.8%. The modified PLS model can be applied to simulate and predict the spring discharge because it can achieve better fitting effect and forecast precision. The result can provide certain theoretical basis for reasonable exploitation and utilization of the Liulin spring. Based on the modified PLS model,the forecast results of the spring flux between2010-2012were2.13m3/s,1.99m3/s and2.03m3/s.The natural resources of Liulin spring karst water system were calculated with recharge method and discharge method. The calculation results shows that the natural resources were2.44m3/s and2.76m3/s respectively. The average discharge is greater than the average recharge, it suggested that the karst water system was in over-exploited state. To guarantee the sustainable utilization of the karst water, it is necessary to carry out some protection measures for Liulin spring. |
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