Responses of baseflow in Kuye catchment to the LUCC on the Loess Plateau of China

The variability of baseflow is a comprehensive reflection of land use/cover changes (LUCC) and an important hydrological characteristic considered in maintaining sustainable development of an ecosystem. Daily streamflow data from 1959 to 2005 at Wenjiachuan gauge station in Kuye catchment on the Loess Plateau were used to analyze baseflow responses to the LUCC. Chapman-Maxwell digital filter was used to separate daily streamflow into baseflow and surface flow. Both nonparametric Mann-Kendall test and Pettitt test were adopted to detect the trend of the baseflow and identify its change point. Double mass curves method was also employed to verify the change points. Results are as follows: (1) The average annual baseflow in Kuye catchment was 24.7 mm, accounting for 38% of total runoff. A significantly negative trend of the annual baseflow was detected in the last 50 years. The average change rate was 0.628 mm.a -1 , which was about 2.5% of the average annual baseflow. Two change points occurred in the years of 1980 and 1996. (2) Baseflow regimes, as represented by daily baseflow curves, showed an increasingly dramatic reduction across the high, median and low percentiles of the time and an increase of zero-baseflow days in the catchment. The variability of baseflow represented by baseflow duration curves increased period by period. (3) By considering statistical insignificance detected in annual precipitation, the change of baseflow in Kuye catchment was greatly related to soil conservation measures implemented from the 1970s to 1980s and coal mining development after 1996.