Features and response to climate-driven factors of the runoff in the upper reaches of the Weihe River in 1975-2011
As the largest tributary of the Yellow River,the Weihe River provides a great deal of water sources to the Gansu Province and Shaanxi Province,China,having strategic significance in regional development,ecosystem health and sustainability of socio-economic development in the Yellow River basin.The catchment area of the upper reaches of the Weihe River is 2.579 km2,which occupies 19.1% of the total area of the Weihe River watershed.In this paper,the runoffs at Beidao and Wushan Hydrologic Stations of the upper reaches of the Weihe River from 1975 to 2011 were calculated and analyzed in order to understand the runoff features and their response to climate-driven factors.The climate change characteristics were analyzed using the data of monthly precipitation and potential evapotranspiration,which were estimated by using FAO Penman-Monteith method.After selecting the representative stations,the correlation coefficients between the annual,seasonal runoff and climate-driven factors were calculated,and the sensitivity of runoff to the climate change was analyzed.The following conclusions can be drawn:(1) Annual runoff of the river has obviously decreased as a whole,especially in the 1990s,but shifted to increase in the early 21 st century.(2) Runoff concentrates in the flood season,and had different distribution forms in different decades.(3) Runoff is affected by climate change ; runoff decreases when climate is warm,precipitation decreases,potential evapotranspiration increases and water consumption increases.(4) The response of runoff to climate-driven factors is not stable,changing with time.(5) Both precipitation and potential evapotranspiration contribute to the change of runoff,and the contribution rate of potential evapotranspiration has increased from the 1990s,becoming the major factor to the runoff decreasing.
upper reaches of the Weihe Riverrunoff variationclimate changecorrelationquantitative analysis