气候和人类活动对典型岩溶地下河系统径流年际变化的影响

为揭示气候变化与人类活动对岩溶地下河系统年径流量的影响,以南洞地下河为研究对象,利用其1972-2014年的径流量、降水量和蒸散量数据,分析其年际变化特征。研究结果表明：研究期内径流、降水和蒸散均呈现波动减少的趋势。其中流域内径流整体以0.014亿m³/a的速度减少,降水整体以3.14 mm/a的速度减少,蒸散整体以7.94 mm/a的速度减少。通过有序聚类法和Mann-Kendall法综合确定出径流、降水的突变年份为2002年、2008年。通过累积量斜率变化率比较法,定量分解了不同时期气候与人类活动对径流变化影响的贡献率：综合考虑降水和蒸散因素,以人类活动轻微的T₁（1972-2002年）阶段为基准期,气候变化对径流减少的贡献率在T₂（2003-2008年）、T₃（2009-2014年）时期分别为-86.68%、35.92%,人类活动对径流减少的贡献率在T₂、T₃阶段分别为186.68%、64.08%。可见,人类活动是南洞地下河流域径流量年际变化的主导因素,其中生活、生产的直接耗水和土地利用/土地覆被变化影响下径流过程的变化,共同影响着径流年际变化。

Impacts of climate change and human activities on the interannual flow changes in a typical karst subterranean river,South China

Quantifying the impacts of climate change and human activities on runoff changes is one of challenges in hydrology and water resources researches. In order to reveal the impacts of climate change and human activities on the interannual flow of a karst subterranean river system, this study chose a big karst subterranean river in south China, Nandong subterranean river (NSR) as a research area to analyse the interannual variations of precipitation, evapotranspiration and flow based on the data of flow, evapotranspiration and precipitation of NSR from 1972 to 2014. The results indicated that precipitation, evapotranspiration and flow of NSR during the study period showed a fluctuating decline trend, in which the overall declining rates of precipitation, evapotranspiration and flow were 3.14 mm/a, 7.49 mm/a and 0.014×10⁸ m³/a, respectively. Two inflection-point years in the variations of precipitation and flow, 2002 and 2008 were identified through the sequential clustering and Mann-Kendall test methods. The method of slope changing ratio of cumulative quantity was adopted in estimation of the contributions of climate change and human activities to the flow variations in NSR. Considering the influence of evapotranspiration in NSR, the results, with 1972-2002 as the base period, indicated less effect from human activities. The contribution rates of the climate changes to the flow changes were -86.68% in the T₂ period (2003-2008), and 35.92% in the T₃ period (2009-2014), while the contribution rates of human activities were 186.68% in the T₂ period and 64.08% in the T₃ period. Obviously, human activities were the dominant factor causing the interannual flow change in NSR catchment. Direct water consumption of production and living and the changes of flow processes under the influences of land use/land cover changes exerted a main influence on the interannual flow changes. The results can give us a better understanding of the variation characteristics under the impacts of climate change and human activities and help to reasonably regulate karst water resources.