气候变化背景下横江流域气象-水文干旱时空演变特征

Spatiotemporal evolution characteristics of meteorological and hydrological drought in Hengjiang River Basin under climate change

摘要

【目的】为分析气候变化背景下横江流域气象、水文干旱的时空变化，应对干旱治理和水资源管理。【方法】选取CMIP6模式下4个气象情景模式：SSP1-2.6、SSP2-4.5、SSP3-7.0、SSP5-8.5,并结合SWAT模型预估横江径流，基于SPI、SRI和Copula函数分析横江流域历史时期(1980—2014年)和预测时期(2015—2100年)气象-水文干旱的联合分布特征。【结果】SWAT模型在横江流域具有较强的适用性，径流率定期和验证期的R²、NSE和R_e分别为0.91,0.90,-0.01;0.96,0.89,0.13;历史基准期(1980—2014)流域呈现气象及水文干旱加剧态势，年均降水量与径流量同步减少，年均SPI、SRI均趋近轻度干旱(-0.44),流域大范围气象干旱的重度与轻度频次上升，大部分地区水文干旱中、重度频次显著增加，偶发极端干旱事件；预测期(2015—2100年)降水与径流量将显著上升，气象、水文干旱整体缓解，气象干旱轻度频次显著上升，气象和水文干旱中、重度频次显著下降，但极端气象与水文干旱事件呈增加趋势；横江流域短期(重现期<2 a)干旱风险降低，气象/水文干旱强度趋同；长期(重现期>10 a)则呈现水文干旱对气象干旱的响应滞后性增强。【结论】未来横江流域趋于湿润化，气象-水文干旱得到缓解。因此在治理横江流域气象-水文干旱的同时，也要加强应对湿润化趋势的措施，提高流域水资源规划与管理能力以及防洪抗涝能力。

Abstract

[Objective] To analyze the spatiotemporal variations of meteorological and hydrological droughts in the Hengjiang River Basin under climate change, and to inform drought mitigation and water resource management. [Methods] Four CMIP6 climate scenarios(SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) under the CMIP6 framework were selected, and the Soil and Water Assessment Tool(SWAT) model was applied to estimate runoff in the Hengjiang Basin. Based on the standardized precipitation index(SPI), standardized runoff index(SRI), and Copula function, the joint distribution characteristics of meteorological and hydrological droughts in the Hengjiang River Basin during the historical period(1980—2014) and the projected period(2015—2100) were analyzed. [Results] The SWAT model demonstrated strong applicability in the Hengjiang River Basin, with calibration and validation result showing R², NSE, R_e values of 0.91, 0.90, and-0.01(calibration), and 0.96, 0.89, and 0.13(validation), respectively. During the historical baseline period(1980—2014), the river basin exhibited an intensifying trend of meteorological and hydrological droughts, with annual average precipitation and runoff decreasing simultaneously. The annual average SPI and SRI values approached mild drought levels(-0.44). The frequencies of severe and mild meteorological droughts increased across the river basin, while the frequencies of moderate to severe hydrological droughts significantly rose in most regions, accompanied by occasional extreme drought events. During the projected period(2015—2100), precipitation and runoff were projected to increase significantly, leading to an overall alleviation of meteorological and hydrological droughts. The frequency of mild meteorological droughts was expected to increase significantly, while the frequencies of moderate and severe meteorological and hydrological droughts were projected to decrease substantially. However, the frequency of extreme meteorological and hydrological drought events was anticipated to increase. In the Hengjiang River Basin, short-term drought risks(return period <2 years) would decrease, with meteorological and hydrological drought intensities tending to converge. However, in the long term(return period >10 years), the lagged response of hydrological drought to meteorological drought was expected to intensify. [Conclusion] In the future, the Hengjiang River Basin is projected to become increasingly humid, with both meteorological and hydrological droughts alleviated. Therefore, while addressing meteorological and hydrological droughts in this river basin, measures should also be strengthened to address the trend toward increased humidity, enhance water resource planning and management capabilities, and improve flood control and waterlogging prevention capacities.

关键词

气象干旱 / 水文干旱 / Copula函数 / SWAT模型 / 干旱演变 / 横江流域 / 流域水资源 / 影响因素

Key words

meteorological drought / hydrological drought / Copula function / SWAT model / drought evolution / Hengjiang River Basin / basin water resources / influencing factors

基金资助

国家自然科学基金(42401030)

国家自然科学基金(52109058)

第二次青藏高原科学考察与研究项目(2019QZKK0103)

长江科学院水利部长江中下游河湖治理与防洪重点实验室开放基金(CKWV20241170/ KY)

湖北省自然科学基金(2024AFD212)

三峡大学科研启动基金(2023RCKJ0025)