岩溶洼地抽水蓄能建库适宜性评价体系及目标优选

Evaluation system for the suitability of reservoir construction for pumped storage and optimization of its site selection in karst depressions

为解决岩溶洼地修建抽水蓄能电站选址的实际工程问题,利用DEM数据和ArcGIS平台自动提取岩溶洼地并进行属性分析和计算,开展岩溶洼地建库资源评价及上库库址优选研究。提出洼地坡度、库容、岩组类型、断层、水文地质、上下库竖直距离和距高比7个建库决策关键性影响因子,构建模糊综合评判模型和偏最小二乘通径模型,以生态保护红线和自热保护区为限制性因素,对研究区488个候选洼地进行初步筛选排序。研究结果表明,竖直距离、库容、距高比三个因素对选址决策起到关键性作用;应用GIS地图叠加技术能很好排除因环境因素限制的不可行站点。通过两种模型普选出的前10个优选洼地中共有6个吻合,一致性较好说明评价模型适用性强、评价结果可靠性高;优选出的洼地与指标体系的量化标准基本一致,在工程实例中得到了很好的验证,其中白水塘1#洼地最适合建设抽水蓄能电站。

In the planning policy on modern energy system in China's"14th Five-Year Plan",it is proposed to accelerate the improvement of system for energy production,supply,storage and marketing,and to promote the largescale and high-proportion development of renewable energy,so as to achieve the goal of"carbon peaking and carbon neutralization".Pumped storage is currently recognized as the most mature,reliable,clean and economical means of energy storage.However,the site selection is imminent in order to construct power stations for pumped storage.Taking Guizhou Province as an example,the current planning of site selection and the construction technology of power stations for pumped storage are seldom studied.Karst is distributed in more than 77%of Guizhou's land area,with the peak-cluster depression as the main geomorphological type.As a kind of natural negative terrain,the peakcluster depression has hardly been excavated.But its excellent surrounding sealing,and wonderful geometric and engineering characteristics can save much investment in excavation support.Thus,the peak-cluster depression is an ideal place for building a reservoir.Taking the karst depression as a research object,this study focuses on the practical engineering problem of building a power station for pumped storage in the karst depression.The factors and their degrees affecting the suitability of reservoir construction in the depression are obviously different in different regions;therefore,some typical factors can only be selected as the evaluation indicators.These factors involve those having an important impact on the stability of the reservoir area,the leakage problem and the benefit of reservoir construction.In this study,samples of karst depressions were automatically extracted,and the attribute analysis and calculation were carried out based on DEM data and ArcGIS platform.According to the engineering practice,experts were organized to discuss and score so as to determine the influence factors of the evaluation model.Then the evaluation was conducted respectively in terms of terrain conditions,geological conditions,engineering conditions,environmental conditions,etc.The model of fuzzy comprehensive evaluation and the model of partial least square path have been constructed based on the seven key influencing factors of the decision-making of reservoir construction,including slope,reservoir capacity,petrofabric type,fault,hydrogeology,vertical distance between the upper and lower reservoirs and the ratio of distance to height.Taking the red line of ecological protection and the autothermal protection area as controlling variables,488 candidate depressions in the study area were preliminarily screened and sorted in combination with the geological conditions of the supporting site.The results show that vertical distance,storage capacity and distance-height ratio play key roles in site selection.The application of GIS map overlay technology can eliminate the infeasible sites limited by environmental factors and the candidate depressions in the eco-environmental protection area.The geological conditions of the proposed lower reservoir and water conveyance power house were considered in the selection of the optimal candidate depressions,which effectively avoided the subjectivity and limitations of decision makers.A total of 6 of the top 10 selected depressions by the two models are consistent.Their good topographic conditions,suitable geological conditions,superior engineering conditions and good consistency indicate strong applicability and high reliability of the evaluation model.The two models are mutually matched.The depression selected is basically consistent with the quantitative standard of the index system,which has been well verified in engineering practice.No.1 depression of Baishui pond is the most suitable for the construction of power station for pumped storage.The research methods and results can further promote the resource utilization of karst depressions.