不同流量情景径流对水质组合事件发生概率的影响研究--以淮河流域蚌埠闸为例

Impact of River Flow on Water Quality Combination Events Under Different Scenarios: A Case of Bengbu Sluice in Huai River Basin

河流水量与水质之间相互联系,相互影响,正确认识水量对水质的影响是进行水量水质联合调度的基础.以淮河流域蚌埠闸为例,按蚌埠闸流量高低(低、中、高)分别设置3种情景(对应情景1,2,3),基于Copula函数,分别建立以上3种流量情景下对应的蚌埠闸水质变量(CODMn和NH3-N)的联合分布函数,对上述3种不同流量情景下水质变量不同组合事件发生概率进行了分析.结果表明,蚌埠闸上各种水质超标组合事件的发生概率总体上是随着闸上流量的增加而减小的,以III类水为标准,相对于低流量条件(情景1),中等流量条件(情景2)可以显著降低蚌埠闸上两水质同时超标风险,风险率值从情景1下此类事件的概率41%迅速降低至15%,而高流量条件(情景3)可以进一步降低其概率至3%.研究结果可以为当前淮河流域水量水质联合调度提供决策依据.

Effective joint management of water quantity and water quality of rivers requires a good understanding of the interrelationships between these variables. Using data from Bengbu Sluice,located in the Huai River Basin,joint distributions were set up for two water quality attributes,CODMnand NH3-N concentration,for three different flow scenarios,small（ 1）,medium（ 2） and large（ 3）,and the probabilities of different combinations of water quantity and quality events occurring were calculated. In general,the higher river flow,the lower was the probability of occurrence of water quality joint events. For a water quality management target of Class III,the risk of an event where both water quality attributes exceeded the target was significantly lower for flow scenario 2（ 15% probability of occurrence） compared to flow scenario 1（ 41%probability）. Flow scenario 3 reduced the probability of occurrence to 3%. Analysis of joint distributions such as these can provide useful information to improve joint operation of water quantity and quality in regulated rivers where pollution is a concern,such as those in the Huai River Basin.