Spatiotemporal variations in precipitation in the Three-River Headwater region from 1961 to 2019

This study analyzed the spatiotemporal pattern of precipitation and its future trends in the Three-River Headwater region using the linear regression, moving average, climate trend rate, and recalibration range methods with 59 years (1961–2019) of precipitation data. The data were taken from 13 meteorological stations in the Three-River Headwater region. The results indicated that the average annual precipitation was 470.7 mm in this region and had an increasing trend of 10.31 mm·10 a⁻¹ . The Yellow River had the highest precipitation in spring, the Lancang River had the highest precipitation in the other three seasons, and the Yangtze River had the lowest precipitation in all four seasons. Precipitation in all source regions showed an increasing trend, and the greatest climatic trends in the rate of precipitation, which was seen in spring, were 2.69, 2.11, and 2.80 mm·10 a⁻¹ for the Yangtze, Yellow, and Lancang rivers, respectively. The cumulative precipitation anomaly showed decreasing trends from 1961 to 2002 and an increasing trend from 2003 to 2019. Catastrophic precipitation occurred in 2002. The average annual minimum and maximum precipitation in different years occurred in the periods 1961–1970 and 2011–2019 and were 452.23 and 512.82 mm, respectively. Annual and seasonal precipitation increased from northwest to southeast, and the range in the spatial variation in precipitation was greatest in the Yellow River source region. The climatic trends in precipitation rates during spring, summer, and autumn decreased from northwest to southeast, but the opposite was observed during winter; this indicated that precipitation increased strongly in source regions with less precipitation. The Hurst value of the long-term change in precipitation was larger than 0.5, indicating that future changes in precipitation would be consistent with past trends. A spatiotemporal pattern in precipitation was observed in the Three-River Headwater region, where future precipitation will present an increasing trend.