What do rivers provide

The headwater can come from rainfall or snowmelt in mountains, but it can also bubble up from groundwater or form at the edge of a lake or large pond.

The other end of a river is called its mouth, where water empties into a larger body of water, such as a lake or ocean.

Along the way, rivers may pass through wetlands where plants slow down the water and filter out pollutants. The water that flows in rivers is fresh, meaning that it contains less than one percent salt.

However, rivers still carry and distribute important salts and nutrients to support plant and animal life. For this reason, some of the most biodiverse habitats on our planet can be found around rivers.

Collectively, scientists estimate that all the rivers in the world carry about 3. Fast-flowing rivers carry pebbles, sand, and silt. As the river begins to slow down—as in a wetland, at the outside of a bend, or where the river widens, such as at the mouth—these sediments sink and build up to form deltas. Rivers that overflow their banks also deposit sediment in the surrounding flood plain.

These deltas and floodplains are highly fertile agricultural zones that offer tremendous value to the surrounding people. In Egypt, for example, the Nile River and its adjacent delta helped give rise to the Egyptian empire that built the pyramids.

Humans use rivers for irrigation in agriculture, for drinking water, for transportation, to produce electricity through hydroelectric dams, and for leisure activities like swimming and boating. Each of these uses can affect the health of a river and its surrounding ecosystems. Monitoring the health of rivers, lakes, and streams is important work that is conducted by scientists called limnologists.

Also called hydroelectric energy or hydroelectric power. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.

The Rights Holder for media is the person or group credited. Tyson Brown, National Geographic Society. National Geographic Society. For information on user permissions, please read our Terms of Service. This unfortunately happens across the world. Freshwater habitats account for some of the richest biodiversity in the world, and rivers are a vital, vibrant ecosystem for many species. But even in the UK, over three quarters of our rivers fail to meet required health standards and face multiple threats — putting an increasing pressure on the diverse wildlife that call our beautiful rivers home: from kingfishers to otters and brown trout.

This can be as simple as stopping water from flowing down sloping tractor tracks, which would take valuable topsoil as well as pollutants into rivers and streams. People depend on rivers for their way of life and their livelihoods. For example, in the Yangtze River in China, the introduction of a dam unintentionally prevented carp from spawning downstream, where a commercial fishery was located.

This boosted the carp population and allowed people to continue living off the river, when previously their livelihoods were at stake. Overfishing has caused fish populations to plummet — bad news for the fish, and for the 60 million people in the region reliant on fish in their diets. We provided support to local communities to manage conservation zones and prevent illegal fishing, and as a result local people have found it far easier to live sustainably off the river.

Special protection, such as a Wild and Scenic designation, helps make sure rivers and their ecosystems remain free and healthy for all of us. We all drink water, and the majority of our supply comes from rivers and streams. The health of river ecosystems directly affects the quality of the water we drink. The forest and river act as filters, constantly purifying the water so it requires less chemical treatment and expensive filtration to be clean enough to drink.

A wild river that occasionally floods its banks nourishes floodplain habitat, important for fish and wildlife. Natural floods can also keep invasive species in check and give important cues to fish that swim upstream to spawn. When we protect a wild river we give it room to move, and room to accommodate floodwaters safely.

Wild rivers are fun—and fun can be lucrative. Rafting, fishing, swimming, hiking and wildlife watching all draw people—and therefore money—to areas with healthy rivers. Sometimes those are rural areas with little else to rely on for economic development. River recreation brings jobs into areas that might otherwise turn to less sustainable industries to support their economies. Visitors rent kayaks, buy gas, eat in restaurants and stay in hotels, which all adds up to cash flowing into the community.