三峡水库抗旱功能定位及其旱限水位研究

    Study on drought resistance function orientation and drought-limited water level of Three Gorges Reservoir

    • 摘要: 近年来,极端干旱事件频发对供水安全造成严峻挑战,旱限水位作为水库抗旱响应的关键指标,对于开展水库抗旱调度具有重要意义。针对三峡水库水资源利用调度无明确抗旱功能定位,长江中下游发生较重干旱或供水困难期间抗旱调度方式缺乏的问题,分析论证了三峡水库在长江流域抗旱体系中的定位,解析了三峡水库不同来水及不同下游取水需求情景下的旱限水位方案,并对汛期储水等关键问题进行了探讨。结果表明:①三峡水库抗旱调度宜以保障城镇取水口水位和维持河流基本生态功能为最优先目标,并以荆江及汉口河段为重点区域解决因水位下降而引发的取水困难问题,适当兼顾其他水量调度需求。②采用的3种确定方法中, 长系列法对三峡水库旱限水位设置具有较好的参考性,若要保证三峡水库在遭遇极端枯水情景时按6 800, 7 000 m3/s和7 200 m3/s下泄,则10月底需分别蓄水至167.20, 170.00 m和172.80 m,按现行调度规程调度方式模拟计算水位保障率分别为90.9%, 87.3%和83.6%。③汛期储水需结合中长期预报,利用部分汛期水量提前进行抗旱储备,从而提升长江流域应对极端干旱事件的能力。研究成果可为三峡水库抗旱调度提供科学依据和技术支撑。

       

      Abstract: The frequent occurrence of extreme drought events has posed significant challenges to water supply security in recent years.The drought-limited water level, which is a key indicator for reservoirs to start drought response, plays a crucial role in reservoir drought-resistant operation.The water resource scheduling of Three Gorges Reservoir (TGR) has no clear functional positioning for drought resistance and lacks drought-resistant operation strategies when a fairly severe drought or water supply crisis occurs in the middle and lower reaches of the Changjiang River.To address these limitations, this study analyzed the role of the TGR in the drought mitigation system of the Changjiang River Basin, and the drought-limited water level schemes for different inflow conditions of the TGR and different downstream water demand scenarios were also explored.Besides, key issues such as water storage management during the flood season were discussed.The results indicated that: ① the highest priority for the drought-resistant operation of the TGR should be given to ensuring the water levels at urban water intake points and maintaining the basic ecological functions of the river.The Jingjiang and Hankou River sections should be designated as key areas to address water intake difficulties caused by water level decline, while other water dispatch needs should be appropriately taken into account.② Among the three methods employed, the drought-limited water levels established for the TGR through long-term series method provide a valuable reference.To guarantee a discharge of 6 800, 7 000, 7 200 m3/s during extreme dry water scenarios, the water level of the TGR by the end of October should be impounded to 167.20, 170.00, 172.80 m, respectively.The corresponding water level guarantee rates under current scheduling regulations are 90.9%, 87.3%, 83.6%, respectively.③ It is suggested that water storage during the flood season should be integrated with medium- and long-term hydrological and meteorological forecast, storing part of flood season water as a drought reserve, to strengthen the resilience of the Changjiang River Basin in responding to extreme drought events.The findings can provide a scientific foundation and technical support for the drought-resistant operational strategies of the TGR.

       

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