How rivers are vital to everything from biodiversity to mental health

This article is part New scientist And is joint campaign, Save British rivers. The year-long collaboration will show what is happening to the UK’s rivers and how to restore them through a series of special articles, films, podcasts and events.

Stand by a river in Great Britain and you will be in contact with the ancients. Their short, crude names – Thames, Leith, Tuff, Lagan – tell a lot about the history of the islands, from the ancient Britons to the Romans, Saxons and Vikings. These rivers are part of the past and the present. However, they face an uncertain future.

Throughout the world, rivers are valuable, often sacred, cultural and practical assets. They are the hallmark of human settlements that have been used for thousands of years as a source of drinking water, food, irrigation, waste disposal, energy, navigation, protection and even inspiration.

In the UK, many of these services are just as relevant today. Tap water comes mainly from rivers. Wastewater is discharged into them – preferably purified, but often not. Rivers irrigate crops, nourish homes, divert floodwaters, and float boats. Millions of people spend part of their leisure time lounging on or near rivers.

Great Britain is a river country. Around the world, about 0.8% of the land is covered with fresh water. In the UK, this figure is 3%. It has about 1,500 river systems with a total length of more than 200,000 kilometers, from rugged upland headwaters to sluggish meandering floodplain meanders, through a wide range of habitats in between.

By world standards, these rivers are short, narrow and shallow – “simple streams,” according to the National River Flow Archive at the UK’s Center for Ecology and Hydrology in Wallingford. However, they are extremely diverse in nature. According to a recent report from the UK National Committee of the International Union for Conservation of Nature (IUCN), “Rivers and their flood plains are among the most important natural environments in the UK.”

“It is well known that rivers and their floodplains – and they go hand in hand – support a disproportionate level of biodiversity relative to their size within the landscape,” says report co-author Stephen Addy of the James Hutton Institute in Aberdeen, UK.

Drinking water and flood control

Although rivers are important for many reasons, their most obvious advantage in the UK is the water they supply. According to Water UK, which represents the country’s water industry, about two-thirds of tap water in England and Wales comes from the rivers, reservoirs and lakes they empty into; the rest is taken from aquifers. Northern Ireland and Scotland depend almost entirely on rivers, reservoirs and lakes. A total of 87 per cent of the UK’s water supply comes from these sources.

According to government statistics, water companies in the UK annually withdraw about 4.6 cubic kilometers of river, lake and reservoir water in England for public supply. People drink it, bathe in it, flush their toilets with it, irrigate their gardens with it, and use it to wash their clothes, floors and cars. Offices, shops, restaurants and other businesses also drink it.

Water is taken for other purposes. Electricity generators need 3.4 cubic kilometers to turn steam turbines, while fish and watercress farms use 0.8 cubic kilometers, and agriculture and private water supplies another 0.8. This adds up to 9.6 cubic kilometers, which is equivalent to a cubic reservoir of water over 2 kilometers in all dimensions.

Even in a relatively rainy country like the UK, it milks. The UK government estimates that about one in five surface water sources is depleted due to over-extraction, with indirect consequences for the health of rivers.

The opposite problem – too much water – is an increasingly common hazard in winter. Flooding is an increasing problem as climate change causes extreme weather events, including Bible rainstorms. The UK has had six of the ten wettest years on record since 1998, according to the Environment Agency. Last year, for the first time, three named Atlantic storms were observed within a week.

Natural floodplains can help reduce flood risk by collecting excess water and slowly releasing it back into the river. This is especially true of beaver-created river landscapes, whose dams and ponds greatly slow down the flow of water through the system. Where earlier rain fell to the ground and fell directly into water bodies, now it lingers for several weeks. Beavers are being reintroduced across the UK after being granted legal protection last year.

The problem is that many of these floodplains are far from being natural, let alone being overgrown with beavers: they often contain residential areas and industrial sites that are usually completely useless for flood mitigation.

Water supply and flood protection are two of the many “ecosystem services” provided by rivers. These are vital goods and services such as water, pollination and clean air that come from nature, or what is increasingly referred to as natural capital.

Economic and Health Benefits

The UK was the first country – and remains one of 26 countries – to audit its natural capital. In 2012 the government set up the (now dissolved) Natural Capital Committee (NCC) to advise it on the state of England’s natural capital to help fulfill its commitment to “be the first generation to leave England’s natural environment in a better state than it inherited” . In 2020, the NCC published its first set of invoices.

They are by no means complete as the natural capital summation system called experimental ecosystem accounting is still under development and nature is complex. But they still speak eloquently about the value of rivers.

The water withdrawal alone costs £6.8bn a year – essentially the same amount it would cost to keep the taps running if rivers didn’t supply the UK with water – and the asset is worth £134bn (NCC emphasized that this is not a price). nature tags: given that the natural world supports all life on Earth, its value is limitless). Wetlands sequester 3.5 million tons of carbon per year, worth £831 million; this asset is valued at nearly £30 billion. Hydroelectric power generation produces 6,865 gigawatt-hours per year, worth £136 million; the value of this asset is £2.2 billion.

These “supplying and regulating” services are complemented by less tangible but no less valuable cultural services. Around 1 in 10 of the UK’s 5.8 billion annual recreational and tourist visits are freshwater-related, valued at £681 million; the asset is worth £32 billion. Recreational fishing is a £1.7 billion a year industry. Around 2.7 million people benefit from £870m a year of health benefits from being in or near freshwater. The value of this asset is almost 48 billion pounds. Even house prices benefit from the proximity of the river, worth £2.9 billion a year.

Key habitats for biodiversity

One asset that has yet to be included in the natural capital account is biodiversity, but it is clear that rivers are an important repository of what is left in the UK. Globally, rivers and other bodies of fresh water are disproportionately biodiverse. Although they cover less than 1 percent of the Earth’s surface, they are home to about a third of the described vertebrate species, including approximately 40 percent of all fish.

The UK’s rivers and the wetlands they feed are also disproportionately biodiverse, albeit to a lesser extent. According to the Environment Agency, they are home to about 10 percent of animal species in the UK. The IUCN lists 346 river-dwelling species, some of which are endangered, including eels, otters, godwit and feather mosses. The Environment Agency reports that more than 10% of the UK’s freshwater and wetland species are threatened with extinction.

Rivers are biodiverse in part because they are themselves diverse. A short stretch of lowland river can have 10 different habitats: puddles, riffles (shallow water flowing rapidly over rocks), slips (deeper, slow flowing waters), backwaters, thickets of aquatic vegetation, submerged tree roots, exposed sediments, banks rivers, coastal vegetation and floodplains all provide food and shelter for various species. Further upstream are headwaters, waterfalls and rapids, which are also home to specialized species such as freshwater pearl mussel, whiteclaw crayfish, brook lamprey and goby, as well as juvenile salmon, trout and mullet. These juveniles will eventually migrate to the sea and will be part of the £713 million annual income of the British fishing industry.

Rare chalk flows and poor ecological health

England is also home to the vast majority of the world’s chalk streams, rare and internationally important habitats fed by alkaline chalk aquifers and characterized by gravel and silt deposits and crystal clear water. They are home to unique ecosystems and have been described as the English Great Barrier Reef. There are only 210 such waterways in the world and 170 of them are in England (the rest are in northern France).

Not surprisingly, the value of ecosystem services is closely related to the ecological health of an asset. In most of the UK, this is not a happy story. There are no rivers in England, Wales and Northern Ireland that are considered environmentally sound according to the criteria set out in the four countries’ Water Framework Directives; only 14 percent are good. The rest are average, bad or bad. None of them are in good condition in terms of chemical contamination, and none are in good general health. In Scotland, 8 percent of the rivers are in good ecological condition.

An IUCN report on the subject bluntly concludes that “truly natural [river] An environment that has escaped direct or indirect human impact no longer exists.” However, according to Eddie, there is hope. “There are some grounds for optimism. River restoration in the UK is taking a step-by-step change with more and more projects going on everywhere.”

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