Annual, seasonal, and monthly baseflow trend in an arid area in Loss Plateau, China

Baseflow is a vital water source for environmental and economic growth. To reveal the changes in baseflow in an arid area, Loss Plateau, China, we analyzed the annual, seasonal, and monthly baseflow fluctuations in 1981–1990 and 2006–2010. We discussed the effects of PET (potential evapotranspiration), precipitation, HI (humidity index), and temperature might have on baseflow in the basin. Results showed that the annual baseflow decreased significantly, and seasonal baseflow and baseflow index (BFI) were distributed differently in the four seasons. Baseflow and BFI were stable during the winter, but during May and June, baseflow was unstable while BFI remained stable. During 1981–1990, January and December exhibited a slight variation in baseflow, while January, May, and June exhibited a slight variation in BFI. From 2006 to 2015, baseflow was stable, with limited fluctuations in January, February, March, April, May, November, and December. The correlations between baseflow and PET, precipitation, HI, and temperature were neither statistically significant nor robust. Increases in PET, precipitation, HI, and temperature did not result in a corresponding increase or decrease in baseflow from the annual, seasonal, and monthly time scales.