控制性供水湖泊旱限水位确定方法——以洱海为例

Algorithm for determining the drought-limited water level of controlled water supply lakes:a case study of Erhai Lake

旱限水位作为干旱预警以及工程抗预案的重要指标和依据,对科学指导湖泊开展抗旱调度具有重要的作用。本文针对控制性供水湖泊的特征,在充分考虑湖泊自身生态健康稳定的同时,结合湖泊兴利调节逆序递推计算,提出了一种控制性供水湖泊旱限水位计算方法,以洱海为例,验证了该方法的合理性。结果表明:通过设定旱限水位,在考虑湖泊最小生态需求的基础上,通过在干旱前期预留水量,可有效缓解干旱年份的湖泊周边地区的严重缺水情况;在设置旱限水位后,连旱最不利年份下洱海环湖供水缺水量减少1023万m^(3),引洱入宾农业灌溉用水减少1016万m^(3),环湖城市供水、引洱入宾灌溉严重缺水月数分别减少11、10个,低于最低生态水位月数减少15个。本研究为水旱灾害防御部门制定湖泊旱限水位、指导湖泊开展抗旱调度提供了一套通用算法,能够为干旱防御决策提供科学依据和技术支撑。

As an important indicator and basis for early warning of drought,water shortages,and anti-drought planning in water conservancy projects,the drought-limited water level(DLWL)plays an important role in scientific guidance of the drought control of lakes.This study focused on the characteristics of controlled water supply lakes,while also fully considering the ecological health and stability of the lakes and combining with the reverse recursive calculation of lake utilization regulation.Thus,we developed a method for calculating the DLWL of controlled water supply lakes.The rationality of this method was verified through a case analysis of Erhai Lake,Yunnan Province,China.The results showed that the severe water shortage in drought years can be alleviated effectively by setting the DLWL and considering the minimum ecological demand of the lake.The maximum reduction in water shortage for the water supply of the region surrounding Erhai is as high as 10.23 million m^(3),and the maximum reduction in agricultural irrigation water from Erhai entering Binchuan County is as high as 10.16 million m^(3).Additionally,the water shortage rate and period in each industrial sector can be reduced significantly in areas around the lake.The time period during which the lake is below the ecological water level can also be reduced significantly.After setting the DLWL,the number of severe water shortage months for lake water supply and the Erhai water entering Binchuan County irrigation was reduced by 11 and 10 months,respectively,and the duration time below the ecological water level was reduced by 15 days.This study provides a general algorithm that can be used by flood and drought disaster prevention departments to establish a DLWL and guide the drought-relief operation of a lake,which can provide the scientific basis and technical support required for drought prevention.