未来气候变化情景下嫩江流域极端水文演变特征

Characteristics of extreme hydrological evolution in Nenjiang River Basin under future climate change scenarios

摘要

【目的】嫩江流域地处中高纬度地区，对全球气候变化极为敏感，因此，需进一步探究未来气候变化下嫩江流域极端水文变化趋势，为区域洪旱灾害管理提供理论支撑。【方法】选取嫩江流域控制水文站—大赉水文站，以1963—2018年为历史时期，以CMIP6不同SSP情境下(SSP126、SSP370和SSP585)气象要素数据为驱动，采用率定和验证后的HYDROTEL模型模拟未来气候变化下2025—2100年日径流量，并提取洪峰流量指标(最大日流量、最大5 d流量和丰水天数)和枯水流量指标(枯水天数和连续干旱天数),分析未来气候变化下嫩江流域极端水文演变特征。【结果】结果表明：(1)未来气候变化下，嫩江流域不同SSP情景下极端水文风险变化趋势差异明显。三种情景下洪峰流量指标均无显著性变化趋势；在SSP1-2.6情景下枯水流量指标呈显著上升趋势，而在SSP3-7.0情景下枯水流量指标呈显著下降趋势；在SSP5-8.5情景下连续干旱天数呈显著性下降趋势。(2)不同时段，洪峰流量指标和枯水流量指标变化趋势和波动特征有所差异。三种情景下在近期(2025—2050年)、中期(2051—2070年)和远期(2071—2090年)不同指标均值相较于历史时期存在一定差异，特别在SSP5-8.5情景下远期最大日流量、最大5 d流量均值相较于历史时期分别偏高44.3%、38.2%。【结论】未来随着辐射强迫的增加，发生洪涝的强度和频次呈明显的上升趋势，发生干旱的强度和频次呈一定的下降趋势。分析未来气候变化情景下嫩江流域极端水文演变特征，可为嫩江流域的农业旱涝风险对应、流域水安全保障以及水资源综合管理等提供了一定的参考。

Abstract

[Objective] Global climate change causes frequent occurrence of extreme hydrology, threatening regional water security and ecological security. The Nenjiang River Basin is located in the middle and high latitudes and is highly sensitive to global changes. However, how hydrological extremes will evolve under future climate change remains unclear. [Methods] Selecting the Dalain Hydrological Station, a control hydrological station in the Nenjiang River Basin, changes in hydrological extremes were investigated under future climate change. The meteorological data under different SSP scenarios(SSP126, SSP245, and SSP585) of CMIP6 were used as driving climatic factors. The calibrated and validated HYDROTEL model was employed to simulate the daily runoff volume from 2025 to 2100 under future climate change. Peak flow indicators(maximum daily flow, maximum 5-day flow, and flood days) and low-flow indicators(low-flow days and consecutive dry days) were extracted to analyze the extreme hydrological evolution characteristics of the Nenjiang River Basin under future climate change. [Results] The result showed as follows:(1) Under future climate change, the variation trend of extreme hydrological risk in Nenjiang River Basin under different SSP scenarios will be divergent. There is no significant change trend in the peak discharge index under the three scenarios. In the SSP1-2.6 scenario, the low water flow index will witness a significant upward trend, while in the SSP3-7.0 scenario, the low water flow index will experience a significant downward trend. Under the SSP5-8.5 scenario, the number of consecutive drought days will witness a significant decreasing trend.(2) The change trend and fluctuation characteristics of peak flood discharge index and low water discharge index are different in different periods. In the three scenarios, the mean values of different indicators in the near term(2025—2050), the medium term(2051—2070) and the long term(2071—2090) show certain differences compared with the historical period. Particular in the scenario of SSP5-8.5, the mean values of the long-term maximum daily flow and the maximum 5 d flow will be 44.3% and 38.2% higher than during historical period respectively. [Conclusion] Under the future climate change, the intensity and frequency of floods will show a significant upward trend, while the intensity and frequency of droughts will show a certain downward trend in the Nenjiang River Basin. It can provide important references for the mitigation of agricultural drought and flood risks, water security guarantee, and comprehensive water resources management in the Nenjiang River Basin.

关键词

嫩江流域 / 历史时期 / 未来气候变化 / 极端水文指标 / 变化趋势 / 时空变化 / 极端降水 / 洪水

Key words

Nenjiang River Basin / historical period / future climate / extreme hydrological index / trend / spatiotemporal changes / extreme precipitation / flood

基金资助

国家重点研发计划项目(2021YFC3200302)

国家自然科学基金项目(U2243230)

国家自然科学基金项目(421010514)

国家自然科学基金项目(42207088)