为了缓解天津水资源严重短缺的困境,利用层次分析法,从水资源保证程度、调水协调难度、可供水量、工程成本、供水管网改造成本、水质、水处理成本、污水处理难度、生态环境风险等角度对天津市主要后备水源进行了综合对比评价。评价结果认为海水淡化、南水北调中线调水、地下咸水开发、海水直接利用可以作为天津市理想的后备水资源开发方案;上游水库调水、南水北调东线调水、引黄调水可以作为应急后备水源方案;污水处理后主要用作灌溉、生态、景观用水。

As a city with serious water shortage problem,Tianjin has an urgent need to find new water sources in order to meet the growing demand for water supply.The standby water sources schemes in Tianjin include middle and east routes of south to north water transferring from Yangtze River,importing water from Yellow River,redeploying water from upstream reservoirs of Haihe River,effluent reuse,seawater for direct use,seawater desalination,saline ground water development,etc.In our research,we use analytic hierarchy process to evaluate these schemes with a comprehensive analysis on nine factors,including water supply,difficulty of water source sharing,annual volume of water supply,cost of engineering construction,quality of water,cost of water treatment,cost of water supply pipelines reticulation,handicap of wastewater disposal process and risk of eco-environment.First we analyzed each scheme with the nine factors.Then we used Delphi technique to decide the relative importance of these factors and got a judgment matrix to acquire the weight of them.As a result,seawater desalination got the highest value with the virtue of huge quantity of reserves,high quality of water supply,low ecological and climatic risks and short distance of intake.The middle route water transfer project,saline ground water and direct use of seawater also got higher mark profiting from large reserves,extensive and lower cost.The comparative assessment result indicates that these four schemes are felicitous water sources for municipal utilization in Tianjin.The east route water transfer project,redeploying water from upstream reservoirs and importing water from Yellow River got lower values with disadvantage of water pollution or serious regional contest.They can be only treated as contingent water sources.Although sewage disposal got the lowest mark because of high cost of treatment and supply pipelines construction,sewage treatment must be given priority to be used in irrigation,ecological and landscape demand.