Comprehensive Evaluation And Decision-making Of Drinking Water Source

Due to the acceleration of industrialization and urbanization,the threat to drinking water is also increasing.The evaluation of daily operation and management of water sources has become an important part of drinking water protection.There were great differences in natural conditions and operation among different types of water sources.Therefore,it is necessary to establish a unified evaluation system that can accommodate the differences of different water sources.In this paper,the evaluation methods of the current indicators about water sources and the system analysis methods of water resources were reviewed.The application of SWOT（situation）analysis was used to clarified in the field of water resources.In order to meet the requirements of scientificity and standardization,the evaluation and decision-making system of drinking water sources based on combined AHP-VIKOR-SWOT methods was established.Taking a case study in Changtan Reservoir which was located in Taizhou,Zhejiang Province,a comprehensive evaluation of reservoir-type water sources was carried out.The study discussed the current status of water quantity,quality,ecological environment and engineering management of the Changtan reservoir.Based on the hierarchical structure of the target water source area combined with the SWOT classification of current factors,a comprehensive evaluation of the water source area of Changtan Reservoir was carried out.The following conclusions were obtained:（1）The evaluation and decision-making system of drinking water sources based on combined AHP-VIKOR-SWOT methods was established.The most inferior elements in the hierarchical structure were classified according to internal and external conditions,and the comprehensive level of the current water source was determined.The VIKOR algorithm was used to sort the subsequent strategies.Under the correction of the current conditions and the simulation conditions,a compromised optimal development plan was obtained.（2）The current state of water storage in Changtan Reservoir was good,but the water pressure in the area where it located was high.The dispatching plan of the reservoir still needs to be improved.The EWQI method was used to evaluate the water quality of 64 water samples at the three monitoring sections of the Changtan Reservoir.The results show that the conventional water quality in the reservoir area was generally good.The eutrophication evaluation grades were all mesotrophic,but the seasonal and local water bloom phenomenon in the reservoir area presented a significant weakness.The surrounding environmental conditions and ecological structure of the reservoir area were not conducive to the self-purification and release of pollutants in the sediments,and there were significant weaknesses.In addition,the vegetation structure around the reservoir and the slope protection conditions also showed weaknesses.The current conditions of reservoir engineering management were generally good,but the average operating water level of the reservoir for many years was far lower than the designed normal water level,so that the reservoir’s water storage and water supply capacity had not been fully utilized（3）The SWOT comprehensive evaluation grade of Changtan Reservoir was medium,and the CEI（Comprehensive Evaluation Index）was 2.97.Among the 25 secondary indicators of water sources,there were 9 strengths,8 weaknesses,5 opportunities,and 3 threats.The strategic quadrilateral determines that Changtan Reservoir was an ST（Strength-Threat）type of water source,i.e.,in the current situation of the water source,the internal strengths were stronger than the weaknesses,and the external threats were greater than the available opportunities.（4）Ten relevant measures to promote the subsequent development of water sources were proposed as alternative strategies.The strategy of improving the ecological environment in the reservoir area（WO₂）and the strategy of remediation of sediment in the reservoir area and the conventional water quality protection strategy（ST₂）were listed as the best compromise strategy.According to the relative implementation degree and the correction of water quality and water volume forecast results,the first step of the subsequent construction management plan for the water source area should be to improve the water quality of the reservoir.The second step was to improve the water supply and storage structure of the reservoir and improve the level of water management and dispatch.The third step was to improve the ecological environment,such as focusing on dredging sediments in reservoir areas and improving vegetation in protected areas.The fourth step was the related strategies of water source engineering management,such as solving the problem of substandard operation of reservoir engineering facilities and improving the flood discharge and storage capacity of the dam.This study provides a well-structured model for the comprehensive evaluation and decision-making of the status quo of different types of drinking water sources,which had important practical significance for the construction and management of water sources and their protection areas.