泾河合水川流域近50年径流演变特征及影响因素分析

在泾河合水川流域1964~2011年的年降雨、径流变化特征分析基础上,利用Mann-Kendall法、双累计曲线法定量分析了其趋势及相互关系,并探讨了变化成因。结果表明,1964~2011年的年降雨量呈轻微下降趋势（P=0.52）,年变率-0.04 mm/a;径流深呈不显著下降趋势（P=0.97）,年变率-0.10 mm/a。变化趋势与泾河东北部、黄河河口-龙门区间西南部类似,与黄河中游其它子流域差异较大。二者突变年份分别为2000年和1978年。1964~1978年是该流域降雨-径流关系的天然时期,1979年后受水保工程修建、植被覆盖增加等人类活动影响,降雨-径流关系发生变化。

Runoff Evolution and Its Impacting Factors in the Heshuichuan Basin of the Jinghe River in the Past 50 Years

Amount of stream water in the Huanghe River has decreased dramatically in the end of 1990s. Researches showed that the runoff dynamics and relationship between runoff and precipitation in sub-basins in the middle reach of the Huanghe River were different according to basin location and time interval. In this arcitle, we investigated the dynamics, anomalies as well as the changing trends of annual precipitation and runoff in the Heshuichuan Basin in the Jinghe River during 1964-2011. In the meanwhile, the possible impacting factors for the evolution trend were explored. Results showed that: 1) Annual precipitation varied from 338.15 mm to 811.2 mm with an average of 525 mm during 1964-2011, both maximum and minimum annual precipitation presented in the 1960s. Annual runoff depth varied between 7.85 mm and 59.52 mm with an average of 17.72 mm. Annual precipitation and runoff decreased during 1964-2011 with a rate of -0.04 mm/a (P=0.52) and -0.10 mm/a (P=0.97), respectively. The turning points for annual precipitation and runoff were different, runoff turned to decrease in 1978, while annual precipitation turned to increase in 2000. 2) Dynamics and changing trend of annual precipitation and runoff in the Heshuichuan Basin were similar to sub-basins of the Jinghe River located in the North and Northeast part. They were also similar to sub-basins of the Huanghe River located in the Southwest part of middle reach (Hekou-Longmen) region. Influenced by many kinds of natural factors and human activity, the hydrologic factors change differently in different geographical position and different size of basin. 3) In the period of 1964-2011, annual rainfall was correlated to runoff with a coefficient of 0.53, suggesting that the overall trend of runoff was dominated by precipitation in this basin. However, the correlation and double mass curve of annual precipitation and runoff varied among time intervals. Rainfall was correlated with runoff during 1964-1978 with a coefficient of 0.75, indicating that the human influences were smaller than precipitation change during this period. The double mass curve of rainfall-runoff deviated downward since 1979 and amplified during 2004-2011, suggesting that the rainfall-runoff relationship had changed due to human activities since1979. This change can be inferred to the enhanced soil and water conservation measures since 1979, as the amount of terraces, backbone dams and check dams were increased. More important, the weaker rainfall-runoff correlation since 2004 can be related to the dramatic land use/cover change caused by the “grain for green” policy.