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首页 考试资讯考研英语 2024考研英语同源外刊1月:干枯的河流


时间:2024-01-11 14:30:47 编辑:


A model of the world’s rivers and streams has been developed to predict which of these watercourses flow all year round and which go dry. The analysis shows that rivers and streams that run dry are ubiquitous throughout the world:

The flowing waters of surface rivers and streams efficiently transport sediment, organic material and nutrients, among other things, from hillsides and overland areas to downstream lakes, reservoirs and the ocean. Along the way, rivers and streams provide important resources for our communities and support rich, complex ecosystems. Non-perennial streams, which do not flow year-round, are crucial in this context.

However, because non-perennial streams are less reliable sources of surface water than perennial ones, they are less-well studied than their perennial counterparts:

Messager and colleagues combined streamflow data from sites around the world with information describing the hydrology, climate, physical geography and land cover at those sites, to model the probability that water does not flow for at least one day per year. They then expanded their predictions to all stream segments recorded in a global stream-network database (RiverATLAS):

The authors report that 51–60% of the world’s streams do not flow for at least one day per year, and that 44–53% of global stream length is dry for at least one month (about 30 days) each year:

Their modelling shows that non-perennial streams occur in all climates and biomes on every continent. The model also shows that 95% of the stream network in hot, dry regions — which represent 10% of the global landmass — runs dry each year. Astonishingly, even segments of major rivers, such as the Niger River in West Africa, are predicted to dry up in these arid regions:

The vast prevalence of non-perennial streams in such locations highlights how even streams that do not flow continuously substantially affect water availability and water quality. The results emphasize the need for more-detailed maps of perennial and non-perennial flows at regional and local scales, and for further studies of how non-perennial streams affect overall water availability and quality.

Small headwater streams (those that have no tributaries) make up 70–80% of stream length worldwide, similar to the way in which the collective length of one’s fingers is much greater than the length of the palm of the hand:

Messager and co-workers’ model predicts that, even in the wettest regions, such as the Amazon River basin and portions of central Africa and southeast Asia, up to 35% of these headwater streams stop flowing at some point in the year:

However, it should be noted that headwater streams are monitored by relatively few stream gauges, which tend to be located on larger, perennial rivers downstream. The model might therefore provide highly uncertain estimates for the upstream regions of stream networks:

Lack of streamflow data is a common problem for the modelling of headwater streams, and so data-collection efforts are being implemented to fill this knowledge gap:

Stream gauges are also scarce for non-perennial streams more generally. In Messager and colleagues’ analysis, for instance, there were no gauges in non-perennial streams in Argentina; just one in New Zealand; and 10 in the United States Pacific Northwest, out of a network of 250 gauges:

To improve models that map perennial and non-perennial streams, low-cost field observations will be needed, coupled with the development of high-resolution remote-sensing technology that frequently detects — or at least predicts — surface flow in streams:

Messager and co-workers’ analysis provides a robust, quantitative confirmation of the ubiquity of non-perennial rivers. Their results indicate the need for a fundamental change in the fields of river and stream science and management, in which non-perennial streams have been largely overlooked:

In arid regions, the predominance of non-perennial streams might be a major driver of water availability and quality. And in areas where services developed by humans are not readily available, ecosystem services such as flowing water in streams are used to meet basic needs and will, in part, determine the well-being and prosperity of people in that area. The new findings therefore shine a light on the need for global accounting of both perennial and non-perennial streams:

Moreover, changes in the distribution of streams can have far-reaching impacts on carbon and biogeochemical cycles at global and continental scales, and on the survival of stream-dwelling organisms, including many endangered species. A global benchmark of the prevalence of perennial and non-perennial streams is therefore crucial for evaluating the effects of future changes in their distribution associated with climate and land-use change.

ubiquitous (adj.) - 普遍存在的
Example: Air pollution is ubiquitous in large cities around the world.
ubiquity (n.) - 普遍存在
Example: The ubiquity of smartphones has transformed how we communicate.
hydrology (n.) - 水文学
Example: The hydrology of the region plays a crucial role in determining water availability.
biome (n.) - 生态群落
Example: The tropical rainforest is a unique biome with high biodiversity.
perennial (adj.) - 常年的,四季不断的
Example: Evergreen trees are examples of perennial plants that retain their leaves throughout the year.
streamflow (n.) - 河流流量
Example: Scientists monitor streamflow to understand the dynamics of river ecosystems.
headwater (n.) - 源头,河源
Example: The headwater of the river is often the purest source of water.
gauges (n.) - 仪表,测量仪器
Example: The weather station is equipped with various gauges to measure temperature and humidity.
remote-sensing (n.) - 遥感技术
Example: Satellite imagery relies on remote-sensing technology to monitor changes in the Earth's surface.
far-reaching (adj.) - 深远的
Example: The new policy will have far-reaching implications for the economy.

原文: "Moreover, changes in the distribution of streams can have far-reaching impacts on carbon and biogeochemical cycles at global and continental scales, and on the survival of stream-dwelling organisms, including many endangered species."
翻译: 此外,河流分布的变化可能对全球和大陆尺度的碳和生物地球化学循环产生深远的影响,同时对栖息在河流中的生物,包括许多濒临灭绝的物种的生存产生影响。







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