锡林河流域径流变化规律及气候波动和人类活动影响的定量分析

Quantitative Analysis of Runoff Variations as Affected by Climate Variability and Human Activity in the Xilin River Basin

多种原因导致内蒙古高原内陆河草原流域草地退化及环境恶化,定量分析其径流变化规律和影响因素对于流域的生态保护具有重要的意义。基于内蒙古锡林河流域1963—2015年水文、气象和社会经济等数据,采用累积距平法、双累积曲线法、改进的M-K趋势检验法和累积量斜率变化率比较法等方法,从年代、水文年及季时间尺度剖析了锡林河流域径流演变的规律,定量计算了气候波动和人类活动对锡林河径流变化的贡献。结果表明:锡林河流域径流量在各时间尺度均为显著(p<0.05)减少趋势,而各气候要素的波动变化趋势不明显,但流域内社会经济变化显著;径流量在21世纪初达到最小,相对于20世纪90年代减少了54.9%;流域内降水、径流变化的突变年份均为1998年,1998年前后气候波动对径流减少的贡献率仅为30.34%,而人类活动对径流减少的贡献率达到69.66%,人类活动是引起径流量减少的主要驱动因素。

Various factors can be related to grassland degradation and environmental deterioration in the grassland inland river basins of Inner Mongolia Plateau.To protect the vulnerable grassland ecosystem,it is needed to understand the variation mechanisms of runoff and the causal factors.Using data on hydrology,meteorology,and socioeconomics from 1963 to 2015 of the Xilin River basin,we identified runoff variations at various time scales,including age,hydrologic year,and season,and analyzed contributions of climate variability and human activity to the identified variations.The identification was done using four methods,namely cumulative anomaly,cumulative double-mass curve,modified Mann-Kendal(M-K)trend test,and slope inflection of cumulative variable curve.The results showed that regardless of the time scales and at a significance level(α=0.05),the runoff exhibited the significant decreasing trend while the climate variables(e.g.,precipitation)did not show any significant trend,but the socioeconomics had the rapid increasing trend.The runoff reached its minimal value in 2000s,which was 54.9%smaller than that in 1990s.Both the precipitation and runoff exhibited the abrupt change around 1998.About 30.34%of the post-versus pre-1998 runoff decrease might be caused by the responding precipitation decrease,while the remaining 69.66%could be attributed to human activity.Thus,for the study basin,human activity was probably the primary driver for the runoff reduction.