| The characteristics of the hydrological cycle are closely related to climate evolution and ecological protection.As the first major river in Guizhou Province,the Wujiang River has unique hydraulic resources.Examining the spatial and temporal distribution characteristics of water vapour content,precipitation and evapotranspiration in the basin and their correlations provides a reference for studies to grasp the characteristics of the hydrological cycle,the characteristics of water resources regeneration and use and to explore the climate formation mechanism in the basin.This paper investigates the spatial and temporal distribution of water vapour content,precipitation and evapotranspiration in the basin at different time scales based on the measured data and ERA5 reanalysis data from 15 meteorological stations in and around the Wujiang River basin from 1992 to 2021,and uses various time series analysis methods such as the cumulative distance level method,M-K trend and abrupt change test,and synergistic kriging method.The study also explored the correlation between the three components and further predicted the future development trend.The main findings of the study are as follows:The multi-year water vapour content in the basin shows a slightly increasing trend,with a narrow range of inter-annual values and little dispersion;among the four seasons,only winter shows a slight decreasing trend,with the mean values ranked in order of summer,autumn,spring and winter;the month-by-month water vapour content shows a unimodal distribution,with a peak in July and the most pronounced increase in April.The summer water vapour content is the largest,and its trend is more consistent with the inter-annual water vapour content trend,and the sudden change in time is close to the most representative within the year.The spatial distribution of water vapour content is uneven,but the overall variation is small,mainly increasing from the north-east to the south-west,with the maximum values concentrated in Anshun,Guiyang and Kaili in the middle and upper reaches of the basin,and less in the lower reaches.Precipitation in the basin is abundant and tends to increase between years,with a wide range of variation and a large degree of dispersion in values.The seasonal characteristics of precipitation are obvious: an increasing trend in spring and autumn,and a decreasing trend in summer and winter,with the mean size ranked summer,spring,autumn and winter,and the average precipitation in summer is about seven times that in winter.The monthly scale varies significantly,with a unimodal distribution of precipitation from month to month,with a peak in June and the most significant increase in April,but the average monthly precipitation is not very efficient.The spatial distribution of precipitation is uneven and the extremes vary widely,mainly increasing from west to east,with the maximum values in the lower reaches of the basin in Sinan,Guizhou and Enshi,Hubei,and relatively less in the upper reaches of the basin in Weining and Bijie,Guizhou.The mean value is in the order of summer,spring,autumn and winter,with the average evapotranspiration in summer being about five times higher than that in winter;the month-by-month distribution of evapotranspiration is unimodal,with a peak in July and the largest increase in March.The spatial distribution of evapotranspiration is uneven,increasing from west to east,with the maximum value occurring in the eastern part of the lower middle basin and the minimum value in the upper basin near Weining,Guizhou.The partial correlation analysis shows that water vapour content is more closely related to precipitation than to evapotranspiration in the Wujiang River basin;the complex correlation analysis of multi-year water vapour content with precipitation and evapotranspiration in the Wujiang River basin shows a strong correlation,indicating that water vapour content is influenced by both precipitation and evapotranspiration,and most areas pass the significance test,and the influence is more significant downstream.Water vapour content,precipitation and evapotranspiration in the basin have all shown an increasing trend over the past 30 years and will continue to do so for some time to come.Precipitation at each site has shown a decreasing trend at 5 sites over the past 30 years,while the remaining 10 sites have shown an increasing trend;the trend of precipitation over the future period is that 6 sites will show a decreasing trend and the remaining 9 sites will continue to show an increasing trend due to positive and negative persistence.Over the past 30 years,the average annual evapotranspiration of each site has been decreasing at 5 sites and increasing at the remaining 10 sites;due to the positive and negative persistence,the trend for the future period is that the evapotranspiration of 6 sites will show a decreasing trend and the remaining 9 sites will continue to increase. |
