英国《自然》杂志 12 月 7 日在线发表的一篇环境学论文，以高分辨率绘制了过去 30年全球地表水分布的变化情况，该研究认为导致变化的主要因素是干旱、水库修建（如筑坝）和水提取。

　　地表水是人类生活用水的最重要来源之一，更是各国水资源的主要组成部分。过去已有研究绘制全球地表水的分布情况，并且跟踪地表水随时间推移所发生的地方性和区域性变化。但是直到现在，一直没有出现全球性的、方法统一的有关地表水逐渐变化的定量研究。

　　此次，欧盟联合研究中心的研究人员让-弗朗科斯·佩凯尔及其同事，分析了拍摄于 1984年至 2015 年之间的 300 多万张地球资源卫星图片，以 30 米×30 米的分辨率量化了地表水的月度变化。研究团队使用一种算法将 30 米×30 米的区域划分为陆地或开放水域（包括淡水和咸水水域，但不包括海洋）。

　　团队成员表示，过去 32 年里，有将近 9 万平方公里的永久性地表水消失了，约相当于苏必利尔湖的面积，其中 70%发生在中东和中亚地区。但是，他们也指出，其他地方也会有新的永久性地表水形成，面积约是已消失地表水的两倍，约为 18.4 万平方公里；而且除大洋洲净减少 1%外，各大洲的永久性地表水均出现净增长。

　　论文作者最后总结称，此次最新数据为认识气候变化和气候振荡对地表水分布的影响，补充了进一步的信息，而且捕捉了人类对地表水资源分布的影响。

　　Jean-Fran?ois Pekel, Andrew Cottam, Noel Gorelick

　　The location and persistence of surface water (inland and coastal) is both affected by climate and humanactivity1 and affects climate2, 3, biological diversity4 and human wellbeing5, 6. Global data sets documenting surface water location and seasonality have been produced from inventories and national descriptions7, statistical extrapolation of regional data8 and satellite imagery9, 10, 11, 12, but measuring long-term changes at high resolution remains a challenge. Here, using three million Landsat satellite images13, we quantify changes in global surface water over the past 32 years at 30-metre resolution. Werecord the months and years when water was present, where occurrence changed and what form changes took in terms of seasonality and persistence. Between 1984 and 2015 permanent surface water has disappeared from an area of almost 90,000 square kilometres, roughly equivalent to that of Lake Superior, though new permanent bodies of surface water covering 184,000 square kilometres have formed elsewhere. All continental regions show a net increase in permanent water, except Oceania, which has a fractional (one per cent) net loss. Much of the increase is from reservoir filling, although climate change14 is also implicated. Loss is more geographically concentrated than gain. Over 70 percent of global net permanent water loss occurred in the Middle East and Central Asia, linked to drought and human actions including river diversion or damming and unregulated withdrawal15, 16. Losses in Australia17 and the USA18 linked to long-term droughts are also evident. This globally consistent, validated data set shows that impacts of climate change and climate oscillations on surface water occurrence can be measured and that evidence can be gathered to show how surface water is altered by human activities. We anticipate that this freely available data will improve the modelling of surface forcing,provide evidence of state and change in wetland ecotones (the transition areas between biomes), and inform water-management decision-making.

　　（来源：Nature, 2016, 540: 418-422 doi:10.1038/nature20584）