近60a来全球河川径流量变化趋势及影响因素分析

Trend and influencing factors of global river discharge in recent 60 years

基于全球2894个流域的河川径流量、归一化植被指数(Normalized Differential Vegetation Index,NDVI)以及气温和降水量长期数据,发现年内月均径流量(MQ)呈上升、下降以及不显著变化趋势的流域比例分别为9.1%、12.4%和78.5%,年内最小月径流量(LQ)呈3种变化趋势的流域比例分别为24.1%、11.7%和64.2%,年内最大月径流量(HQ)呈3种变化趋势的流域比例分别为6.4%、13.6%和79.9%。在区域(大陆和纬度带)和全球尺度上,没有出现LQ下降和HQ上升变化趋势的现象,MQ下降与HQ下降联系在一起,MQ上升与LQ上升联系在一起,表明区域和全球尺度上水资源量及年内分配在过去60多年里是改善的。进一步分析发现,气候变化是导致水资源量和年内分配变化的主要因素。但与年内月极端径流量(LQ或HQ)变化不同的是,发生年内月极端径流量的月份大多发生了显著的改变,这个改变可能对社会和自然生态系统以及依靠自然节律的生产生活方式产生深远影响。

Based on the background of rising temperature,changes in precipitation and its pattern,and increased vegetation coverage and biomass,the changes in global water resources have attracted widespread attention and concern.This paper analyzes the long-term data of river discharge,normalized differential vegetation index(NDVI),annual mean temperature and annual precipitation in 2894 watersheds around the world.Results suggest that for the monthly mean discharge within the year(MQ),the proportion of watersheds with the trend of increasing,decreasing and not significantly changing is 9.1%,12.4%and 78.5%respectively;for the lowest monthly mean discharge(LQ),the corresponding proportion is 24.1%,11.7%and 64.2%respectively;and for the highest monthly mean discharge(HQ),the corresponding proportion is 6.4%,13.6%and 79.9%respectively.On regional(continent and latitude belts)and global scales,LQ decline and HQ rise are not found,MQ decline is associated with HQ decline,and MQ rise is associated with LQ rise,which indicates that the water resources quantity and annual distribution on regional and global scales have been improved in the past 60 years.Further analysis shows that climate change is the main factor leading to changes in water resources and annual distribution.However,different from the monthly extreme discharge(LQ or HQ)changes in a year,most of the months in which the monthly extreme discharge occurs have changed significantly.This change may have a profound impact on society and natural ecosystems,as well as production and lifestyle that rely on natural rhythms.