Evaluation And Optimal Utilization Of Safety Yield Of Underground Karst Reservoir

The development of cities and the restoration and protection of the water environment urgently require the rational development and utilization of groundwater resources.Due to the fragile ecological environment and poor anti-pollution performance in Karst areas,the predatory exploitation of water resources in the past often brings many environmental problems,which can not meet the coordinated and healthy development of modern social economy and ecological environment.The author intended to take the Yong'an Dahu Basin in Fujian Province as an example,discussed its feasibility as a Karst underground reservoir,and studied the use of its regulation capacity to realize the balance of supply and demand of groundwater resources,and also the comprehensive benefits of society,economy and ecological environment.Based on the investigation and evaluation of groundwater resources and the geological environment effect of groundwater exploitation,the author quantitatively calculated the reservoir capacity of Yong'an Dahu basin,evaluated the exploitable groundwater resources from the aspects of water quantity and water quality,analyzed the exploitation potential of groundwater,and put forward the schemes for optimizing the utilization of groundwater resources,so as to improve the regulation and storage capacity of water supply system and water resources strategic reserve capacity.The main achievements were included as follows:(1)The geological and hydrogeological conditions of Yong'an Dahu basin,especially the characteristics of Karst development,have been found out.The Yong'an Dahu basin is a relatively independent open Karst underground reservoir controlled by stratum and structure.The main source of groundwater exploitation in the area is carbonate fissure Karst water,and the groundwater dynamics are mainly affected by rainfall,which has obvious seasonal variation characteristics.(2)The feasibility of establishing Karst underground reservoir in Yong'an Dahu basin was analyzed from four aspects such as space condition,water source condition,ecological condition and aquifer medium characteristics;According to the engineering geological survey results,groundwater dynamic characteristics and flow field data,the boundary and scope of the underground reservoir were determined,and its storage capacity was calculated.The results showed that the study area met the requirements of the construction of underground reservoir and had a good prospect of engineering application.(3)The comprehensive evaluation method was used to evaluate the water quality according to the groundwater quality standard(2017),and the groundwater quality was good,which was classified as class III.The safety yield were 40619.45 m~3/d and36957.48 m~3/d respectively by numerical simulation and groundwater balance analysis methods.Visual Modflow software was used to design three different conditions for ten-year simulation exploitation to ascertain the current safety yield is 36957.48 m~3/d,which can be medium-sized water source location.Both meet the requirements of water quality and quantity of emergency groundwater source.(4)In order to avoid unbalanced development and prevent geological disasters such as Karst ground collapse,the potential of groundwater exploitation was analyzed,which showed that the exploitation potential of groundwater in the Dongpo area was medium,and the exploitation potential of other areas was relatively large.According to the evaluation results and the optimization target of Karst groundwater resources,four disaster control exploitation schemes and optimized utilization measures were proposed,which were zoned exploitation,dual water supply,rainwater resource utilization,and water conservation.The thesis had 48 pictures,30 tables,and 88 references.