Research On Ecosystem Health Evaluation Of Karst Hyporheic Zone

Karst hyporheic zone is the karst fractured zone in a stream bed where groundwater and river surface water mix together. It often appears in forms of springs, streams, flood buffer zones, wetlands, etc. As an important part of aquatic ecosystems, being similar to rivers, lakes and wetlands, karst hyporheic zone will be threatened by the natural factors and human factors. So, it has important practical significance to study the evaluation of karst hyporheic zone ecosystem for the protection and management of karst groundwater environment.On the basis of relevant research experience, the conception and classification of karst hyporheic zone ecosystem was put forward. Based on analyzing ecosystem structure features and recognizing ecosystem threatened factors, the evaluation index system, classification standard and evaluation model were established. Quanlin springs catchment in Sishui county,Jining city was selected as the study area. By means of field surveys, water quality sampling,aquatic organisms collection and identification, the current data of evaluation index for typical karst hyporheic zone ecosystem was obtained. Implying principal component analysis method7 indexes were selected: aquifer medium types, species abundance, intensity of fertilizer, the terrain slope, leisure entertainment functions, environmental cushion and the water quality. By using of spatial overlap analysis within GIS, the evaluation area was divided into 256 subareas. Based on coupling Analytic Hierarchy Process and Improved Entropy Method, the index weight was calculated. Implying Fisher optimal partition method to cluster the index attribute data, the karst hyporheic zone ecosystem health condition of Quanlin springs catchment is divided into four categories: healthy district, relative healthy district, relative unhealthy district and unhealthy district.The evaluation result shows that the health degree of karst hyporheic zone ecosystem presents spatially distributed from southeast to northwest. Healthy district, relative healthy district, relative unhealthy and unhealthy district respectively accounts for 13.56%, 47.45%,11.09% and 27.9% of the entire region. The healthy and relative healthy districts are mainly distributed in scenic spot or surrounding around the scenic area, where springs distributed widely, the arable land is less, non-point source pollution is lighter. Relative unhealthy district is mainly distributed in the eastern of the springs catchment, where the land type is mainlyarable land, the groundwater and fertilizers are over used, spring water is used to fish-farming in high density, non-point source pollution around the springs is more serious. Unhealthy district are mainly distributed in the north, where most springs are dried up, the non-point pollution is severe, and aquatic media types are mainly sandstone, conglomerate, gravel which is vulnerable to pollution. The evaluation results and the actual investigation are consistent. So, the proposed evaluation index system and evaluation model of karst hyporheic zone ecosystem are efficient for the case study.Based on the evaluation result analysis, some relevant protection countermeasures were put forward. Thus the research has great reference value to the protection and restoration of karst springs ecosystem.