A Study on the Streamflow Change and its Relationship with Climate Change and Ecological Restoration Measures in a Sediment Concentrated Region in the Loess Plateau, China

To better understand the driving forces of changes in streamflow (Q), this study analyzed the changes in the hydro-meteorological series by the Mann-Kendall, Pettitt's test and the flow duration curve (FDC) in the Wuding River Basin (WRB), which is a typical river basin in the Loess Plateau. The response of Q variability to climate change and human activities were also quantified by the elasticity method and decomposition method based on the Budyko framework. The results showed that Q exhibited an obvious downward trend at the rate of 0.44 mm/y with a changing point occurred in 1980. Compared with 1961-1980, the greatest reduction in monthly Q during 1981-2007 was found in April (41 %) and the low flows have more distinct decrease than high flows. The precipitation (P), potential evapotranspiration (E (0) ) and catchment characteristics parameter n elasticity of Q are 2.40, -1.40 and -2.51, respectively, indicating that Q variability is most sensitive to human activities. The contribution of climate change and human activities to changes in Q from the two methods are 35 and 65 %, respectively. The ecological restoration (ER) measures, including channel measures and slope measures, were found to be the dominant factors responsible for the decreased Q. Furthermore, changes in Q in 1970-1990 could be mainly ascribed to channel measures while slope measures have played more important roles after 1999 when the Grain-for-Green (GFG) project was implemented. This study could provide scientific basis for how to mitigate effectively and efficiently changes in water resources and guide measures to be implemented in the region under the future climate change.