不同时间尺度孤山川流域水沙关系变化及驱动因素

以黄土高原孤山川流域为研究区,采用Mann-Kendall趋势检验和Pettitt突变检验分析年际尺度水沙变化趋势和突变年份。结果表明:孤山川径流量和输沙量于1965—2014年呈现极显著减少趋势(p<0.01),突变年份为1979年和1996年,据此将研究时段划分为基准期(1965—1979年)、过渡期(1980—1996年)和效益期(1997—2014年)。同基准期相比,过渡期年均径流深和输沙模数分别减少34.11 mm和401.48t/km^2,效益期减少65.05mm和213.09t/km^2。径流深低于10mm时,水沙关系较为离散;高于该值时,水沙关系变化相对稳定。过渡期人类活动的减水减沙贡献率分别为79.12%和86.45%,效益期人类活动减水减沙贡献率分别为86.45%和87.45%。

Variation and Driving Factor of Flow-sediment Relationship in Gushanchuan River Basin at Different Time Scales

The Gushanchuan Basin of the Loess Plateau was selected as the study area. The interannual variation of flow-sediment relationship and the mutation year were analyzed using the Mann-Kendall and the Pettitt test. The results of the runoff and sediment yield of Gushanchuan showed a significant decrease trend (p<0.01) from 1965 to 2014, and the mutation year was 1979 and 1996, according to which the study period was divided into the reference period (1965-1979), the transition period (1980-1996), and the benefit period (1997-2014). Compared with the reference period, the average annual runoff depth and sediment modulus decreased by 34.11 mm and 401.48 t/km² in the transition period, respectively, and decreased by 65.05 mm and 213.09 t/km² in the benefit period. When the runoff depth was less than 10 mm, the flow-sediment relationship was discrete. When the runoff depth was more than 10 mm, the flow-sediment relationship was relatively stable. The contribution rates of human activities for runoff and sediment reduction during the transition period were 79.12% and 86.45%, and the contribution increased to 86.45% and 87.45% in benefit period, respectively.