石羊河流域极端气候变化特征与径流响应关系研究

Characteristics of Extreme Climate Change and Its Impacts on Runoff in Shiyang River Basin

摘要:

全球变暖背景下,区域气候变化加剧,高温、干旱和强降水等极端气候事件频发,改变了流域水文过程,并进一步增加径流变化的不确定性。揭示极端气候变化与径流响应之间的关系,对系统性认识内陆河流域水文响应机制具有重要意义。本研究以石羊河流域为研究对象,基于1960—2021年气象数据及8个水文站点径流资料,选取极端最高气温（TXx）、极端最低气温（TNx）、夏日日数（SU）、热夜日数（TR）、霜冻日数（FD）、连续有雨日数（CWD）、连续无雨日数（CDD）、日最大降水量（Rx1day）、强降水量（R95p）和降水强度（SDII）10个极端气候指数,结合标准化径流指数（SRI）,采用M-K趋势检验、Pettitt突变检验和Morlet小波分析,系统分析极端气候变化特征、径流演变规律及其多时间尺度响应关系。试验结果表明,石羊河流域气温和降水量均呈极显著增加趋势,变化速率分别为0.375℃/(10a)和13.4 mm/(10a),流域整体表现出暖湿化特征。TXx、TNx、SU和TR均显著增加,FD显著减少;Rx1day、R95p和SDII显著增加,而CWD和CDD变化不显著。不同水文站点SRI变化存在明显空间分异,西大河水库、金川峡和沙沟寺上游站点呈显著增加趋势,南营水库、杂木寺和黄羊河水库变化不显著,下游的蔡旗站点呈极显著下降趋势。突变检验结果表明,上游部分站点主要在20世纪80年代至21世纪初出现偏丰突变,而蔡旗站约在1979年发生显著减少突变。蔡旗站与气候因子的关系具有明显阶段性和尺度依赖性,主要集中在2~8 a和8~16 a周期尺度,其中,SRI与降水及极端降水强度类指标的相干关系强于气温类指数。研究结果可为干旱内陆河流域水文变化认识及水资源适应性管理提供科学依据。

Abstract:

Against the background of global warming, regional climate change has intensified, with increasingly frequent extreme climate events, including high temperatures, droughts, and heavy precipitation. These changes have altered watershed hydrological processes and further increased the uncertainty associated with runoff variations. Clarifying the relationship between extreme climate events and runoff responses is therefore essential for systematically understanding the hydrological response mechanisms of inland river basins. Taking the Shiyang River Basin as the study area, the meteorological data and runoff records from eight hydrological stations covering the period 1960—2021 were used. Ten extreme climate indices were selected, including the annual maximum value of daily maximum temperature (TXx), annual maximum value of daily minimum temperature (TNx), summer days (SU), tropical nights (TR), frost days (FD), consecutive wet days (CWD), consecutive dry days (CDD), maximum 1-day precipitation (Rx1day), very wet-day precipitation (R95p), and simple daily intensity index (SDII). In combination with the standardized runoff index (SRI), Mann-Kendall trend test, Pettitt change-point test, and Morlet wavelet analysis were employed to investigate the variation characteristics of extreme climate indices, runoff evolution patterns, and their response relationships at multiple temporal scales. The results showed that both temperature and precipitation in the Shiyang River Basin exhibited highly significant increasing trends, with rates of 0.375℃/(10a) and 13.4 mm/(10a), respectively, indicating an overall warming-wetting tendency. TXx, TNx, SU, and TR increased significantly, whereas FD decreased significantly. Rx1day, R95p, and SDII also exhibited significant increasing trends, while no significant changes were detected in CWD or CDD. Pronounced spatial differences were observed in SRI variations among the hydrological stations. Significant increasing trends occurred at upstream stations, including Xidahe Reservoir, Jinchuanxia, and Shagousi, whereas no significant trends were detected at Nanying reservoir, Zamusi, or Huangyanghe reservoir. In contrast, the downstream Caiqi station exhibited a highly significant decreasing trend. The change-point analysis indicated that several upstream stations experienced abrupt shifts toward wetter runoff conditions mainly from the 1980s to the early 2000s, whereas Caiqi station underwent a significant abrupt decrease around 1979. The relationships between SRI and climatic factors at Caiqi station exhibited clear stage-dependent characteristics and were primarily concentrated at periodic scales of 2~8 years and 8~16 years. The coherence between SRI and precipitation-related indices, particularly extreme precipitation intensity indices, was stronger than that between SRI and temperature-related indices. These findings can provide a scientific basis for hydrological drought identification, runoff variation prediction, and adaptive water-resource allocation in arid inland river basins.