Trends of streamflow in the Tarim River Basin during the past 50 years: Human impact or climate change?

SummaryThe characteristics of hydro-climatic changes in the Tarim River Basin were analysed based on data collected at 39 weather stations and 29hydrological stations for the period 1961–2008 and 1952–2008, respectively. A non-parametric trend test on basin scale for annual data shows an increasing trend of precipitation, relative humidity, vapour pressure, and the aridity index since 1986. Surface temperature started increasing in 1996. A decreasing trend of sunshine started in 1990. The potential evapotranspiration (ET) is calculated by the Penman–Monteith equation, and points out decreasing trend of potential evapotranspiration since 1985. This negative trend can also be detected for wind speed in both the same time scale and spatial extent. The stations with significant increasing trends in annual streamflow are mainly distributed at the southern slope of Tianshan Mountain, which can only be explained by climatic changes. The detected negative runoff trend of the main stream of the Tarim River can be explained by anthropogenic activities (such as irrigation and domestic water use) and climatic changes. A quantitative assessment reveals that local human activities since the 1970s led to a decrease of the water volume diverted into the main stream of the Tarim River Basin, which has been aggravated in the 2000s.

Research highlights
► The temporal and spatial characteristics of climate change of the Tarim River Basin are analysed based on different meteorological variables.
► Change points are detected for all meteorological variables.
► The impacts of Climate change on headstream runoff are positive during past 50 years.
► The detected negative runoff trend of the main stream of the Tarim River can be explained by anthropogenic activities and climatic changes.