黄河头道拐水沙变化多元驱动因子贡献率分析

根据1950—2010年水沙实测资料,采用统计分析方法,通过构建非线性响应模型,辨识了水沙变化主导驱动因子,定量评估了多因子对黄河上游头道拐水沙变化的贡献率.结果表明:头道拐1950—2010年多年平均径流量减少速率为2.23亿m3/a,多年平均输沙量减少速率为0.027亿t/a,1987—2010年径流泥沙减少趋势更为明显,同期输沙量减幅明显大于径流量减幅;1969—2010年气候因子和下垫面因子对头道拐站年径流模数和年输沙模数变化的贡献率均约为2:8,下垫面因子明显占主导地位,其中宁蒙灌区年引水量对年径流模数变化的贡献率最大,达到42%,龙羊峡和刘家峡等水库运用对年输沙模数变化的贡献率最大,达到34%.预计今后兰州以上径流变化和兰州至头道拐区间主要支流来沙变化两大自然因素将是头道拐水沙变化的主导因子;灌区引水和支流水土保持综合治理减沙对头道拐水沙变化的贡献率将居主导地位.

Analysis on the contribution rate of driving factors for the annual water and sediment variations at the Toudaoguai hydrological station in the Yellow River

Based on those observing series of annual water and sediment volumes from 1950 to 2010, a nonlinear response model was built statistically at the Toudaoguai gauging station in the Upper Yellow River in this paper. And the contribution rate of those leading driving factors in the model were estimated quantitatively. The results showed that: From 1950 to 2010, the annual mean runoff reduction is 0.223 billion m³/a, the annual mean sediment reduction is 2.7 million t/a. Especially from 1987 to 2010, the decreasing trends of annual runoff and sediment are more obvious, and the sediment reduction is greater than runoff reduction significantly. From 1969 to 2010, the contribution rate of climatic factors and underlying surface factors for annual runoff and sediment reducing modulus at the Toudaoguai gauging station is 2:8 approximately, underlying surface factors occupied a dominant position. Among them the water diversion in the Ningmeng Irrigation Area is the largest driving factor on the runoff reduction at the Toudaoguai gauging station, whose contribution rate reached 42％. The reservoir operation of Longyangxia and Liujiaxia reservoirs is the largest driving factor on the sediment reduction, whose contribution rate reached 34％. It can be predictable that in the future, the variation of runoff in the main channel of upper reach of Lanzhou, and sediment volume from those tributaries between Lanzhou and Toudaoguai will be the two natural driving factors for the annual water and sediment variations at the Toudaoguai gauging station in the Yellow River. Therefore the water diversion from the main channel for irrigating and integrated management of soil and water conservation in those tributaries will be key methods for controlling the variations of water and sediment.