气候变化下1960-2020年长江源区水文气象要素变化趋势OA

Based on hydrometeorological data from 1960 to 2020,this study systematically analyzed the abrupt changes and monthly-scale variations in runoff depth,precipitation,temperature,potential evapotranspiration,and snow characteristics in the Yangtze River Source Region from 1960 to 2020,employing methods such as the Pettitt non-parametric test and simple linear regression.The results showed that during 1960-2020 in the Yangtze River Source Region,the multi-year average annual runoff depth was 90 mm,which shifted from a declining trend to an increasing trend after 2004.Annual precipitation exhibited a mutation in 1997,increasing at a rate of 0.54 mm/a before the mutation and slightly decreasing thereafter.The mean annual temperature was-4.5℃,with the warming rate accelerating from 0.02℃/a before 1997 to 0.05℃/a afterward,significantly higher than before.Potential evapotranspiration showed an overall increase,with a 6%rise after the mutation.The multi-year average snow depth was 1.7 cm,showing a decreasing trend,with a rate of 0.1 cm/a.At the monthly scale,runoff depth and precipitation showed significant seasonal fluctuations,with summer accounting for over 60%of the annual contribution.Winter temperatures showed the largest increase,exhibiting a typical"cold-season amplification effect".The multi-year average aridity index was 1.8,showing a downward trend,reflecting the regional climate's transition towards humidification.The multi-year average runoff coefficient was 0.2,decreased before 2004 and then rebounded,reflecting the increased complexity of hydrological processes due to factors such as snow melting and groundwater recharge.