库河系统水温特性对气候变化响应研究

Study on response of water temperature characteristics in reservoir-river systems to climate change

摘要

【目的】气候变化加剧，水库热分层特性及下游河道水温的变化对水生态系统的影响成为水资源管理中的关键问题。选取龙羊峡水库探讨气候变化及水库调度对水库水温结构稳定性及下泄水温对下游河道生态的影响。【方法】利用CE-QUAL-W2水动力模型，结合未来四种不同社会发展路径所代表的气候变化及两种水库调度方式，对龙羊峡水库水温及下泄水温进行了模拟分析。【结果】结果显示：(1)气候变暖及低水位调度下的龙羊峡水库温跃层厚度平均15.57 m,温跃层强度平均0.55℃/m,分层稳定期周期为244~281 d;高水位温跃层厚度平均20.57 m,温跃层强度平均0.37℃/m,分层稳定期周期为251~288 d;(2)常规发展路径(SSP-8.5)下泄水温与建库前下游河道水温温差指数在不同调度方式下分别是45.66℃·d和12.39℃·d,均为最小；(3)常规发展路径(SSP-8.5)下泄水温会提前约1个月的时间达到花斑裸鲤的繁殖目标水温。【结论】结果表明：气候变化对库河系统水温特性变化具有显著作用，应对气候变化需要采取合理的调度方式。

Abstract

[Objective] With the intensification of climate change, the effects of thermal stratification in reservoirs and water temperature fluctuations in downstream river channels on aquatic ecosystems have become critical issues in water resource management. This study examines Longyangxia Reservoir to investigate the effects of climate change and reservoir operations on the stability of water temperature stratification and the ecological impacts of discharge water temperatures on the ecosystems of downstream river. [Methods] Using the CE-QUAL-W2 hydrodynamic model, simulations were conducted based on four socio-economic pathways representing future climate change scenarios and two reservoir operation strategies. These simulations examined the water temperature and discharge water temperature of Longyangxia Reservoir. [Results] The result showed that:(1) under climate warming and low water level operations, the average thermocline thickness of Longyangxia Reservoir was 15.57 m, with an average thermocline strength of 0.55 ℃/m and a stable stratification period lasting from 244 to 281 days. Under high water level operations, the average thermocline thickness was 20.57 m, with an average thermocline strength of 0.37 ℃/m and a stable stratification period lasting from 251 to 288 days.(2) Under the conventional pathway(SSP-8.5), the temperature difference index between the discharge water temperature and the downstream river water temperature before reservoir construction was 45.66 ℃·d and 12.39 ℃·d under different operation strategies, both showing the minimum values.(3) Under the conventional pathway(SSP-8.5), the discharge water temperature reached the optimal reproduction temperature for Gymnocypris eckloni approximately one month earlier. [Conclusion] The result highlight that climate change significantly affects the water temperature characteristics of the reservoir-river systems, suggesting that effective operation strategies are essential for addressing climate change.

关键词

气候变化 / 库河系统 / 热分层 / 下泄水温 / 龙羊峡水库 / 影响因素

Key words

climate change / reservoir-river systems / thermal stratification / discharge water temperature / Longyangxia Reservoir / influencing factors

基金资助

国家自然科学基金长江水科学研究联合基金项目(U2340224)