| Water diversion engineering in central yunnan is an important hydraulic engineering, it is significant to solve the serious water shortage problem of central yunnan area including kunming. Carbonate are widely distributed in kunming,33.24percent of the strata what the route have crossed are carbonate, due to the complex geological conditions in the karst area, large-scale karst hydrogeological problems wound likely happen in the construction and operation of water diversion project, Meanwhile the extensive pumping of groundwater may result the decline of regional underground water level easily. It have great impact on the karst water environment Therefore, It is necessary to study the law of karst development in central yunnan and the suitability assessment in karst region. The study could provide a certain basis for route optimization of water diversion engineering.This paper have studied on geological environment conditions. evaluation index are selected through the analysis of the karst hydrogeological problems and their influencing factors in the construction of water diversion project. Then AHP method is used to determine the weights of evaluation index, establishes the evaluation model. This paper use the spatial analysis and overlay function of GIS to evaluate the suitability of water diversion engineering in karst region. At the same time, There have predicted what karst environment geology problems may happen through analysis of the disaster mechanism and hydrogeological conditions. Comprehensive evaluation of the engineering suitability in karst are made through comparing the evaluation results base on the karst disaster mechanism with the results based on GIS. On this basis relevant route optimization and prevention measures were put forward. The main study results are as follows:(1) Enjoying a subtropical humid climate, the development of karst in the study area has the typical subtropical karst development characteristics. Stratigraphic lithology, geological structure, topography and geomorphology, new tectonic movement are the main controlling factors of the karst development in the study area.(2) Research region can be divided into three groundwater systems, respectively is: the east-west river system (â… ), the FuMing basin system (â…¡) and the DianChi system (â…¢) through analysis of the law of karst development, the karst aquifer and its watery, the recharge-runoff-discharge characteristics and hydrochemical characteristics.(3) The characteristics of formation lithology, geological structure, topography and geomorphology, development degree of karst, the karst aquifer and its watery, karst morphological distribution characteristics, design parameters of tunnel have important influence on the formation of karst disaster, evaluation index are selected through analysis of the karst hydrogeological problems and their influencing factors in construction of the water diversion project. The AHP method is used to establishes the evaluation model. After that this paper use the spatial analysis and overlay function of GIS to evaluate the suitability of water diversion engineering in karst region. This paper can come to the conclusion that the length of the poor suitability area, middle suitability area, good suitability area that the water diversion project have covered is25.16km,25.34km,15.76km respectively, accounted for16.78%,16.90%,10.51%of total line length.(4) Preliminary prediction is made of water volume, the affected area of water outburst and karst collapse through analysis of the disaster mechanism and hydrogeological conditions. the suitability of water diversion engineering in karst region are evaluated from the angle of disaster mechanism..(5) By comparing the evaluation results base on the karst disaster mechanism with the results based on GIS, This paper can come to the conclusion that the risk of water gushing is extremely high in the poor suitability area, the risk assessment results of the water-fathering problems compared to the evaluation results of the engineering suitability in karst may differ one level, very few differ two levels, the affected area of water outburst have the tendency that the poorer suitability the larger affected area on the whole.80%of the karst collapse may occur in poorer suitability area,20%distribute in middle suitability area.Comprehensive evaluation of the engineering suitability in karst are made base on the comparison result. This paper can come to the conclusion that in addition to the individual line segment, the evaluation result of the engineering suitability in karst based on GIS have high reliability. the evaluation result based on GIS can be choosed as the final result, at the same time the errors of the evaluation result could be modified.(6) According to the comprehensive evaluation result, the route should be optimized firstly to prevent the karst disaster of water diversion project; secondly, appropriate measures should be taken to ensure the safety in construction and minimize the impact on groundwater environment. |
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