澜沧江流域干燥度时空演变纬度特征OA

The Lancang River Basin in China spans about 13° of latitude and has significant altitude gradients.Quantifying how aridity varies with latitude helps interpret hydrological responses and supports differentiated water-resources management.Using the United Nations Environment Programme(UNEP)aridity index and publicly available high-resolution datasets,we divided the basin into 26 latitudinal bands at 0.5°N intervals.We examined interannual and seasonal aridity-index variability from 1940 to 2022.We estimated trends and tested their latitudinal dependence.The research results show that the spring aridity index in-creased significantly(slope=0.001 677,Z=2.38),indicating an overall wetting tendency across the basin.The aridity-lati-tude relationship shows clear spatial and seasonal contrasts.It is negative south of 24.75°N and positive north of 30.5°N.The central basin shows a seasonal transition and a clear latitudinal differentiation with a boundary at 27.25°N.The long term trend of aridity index north of 27.25°N are significantly higher than those in the southern basin(p<0.001).These results reveal a robust latitudinal pattern of aridity change and provide evidence for adaptive water-allocation strategies under climate change.