Water: our rivers, lakes & wetlands... | WWF

Water: our rivers, lakes & wetlands...

Freshwater can be defined as water with less than 0.5 parts per thousand of dissolved salts. (Seawater or Brine has more than 50 parts per thousand)

The ultimate source of fresh water is rain and snow.

Freshwater systems are the rivers, streams, lakes, ponds, groundwater, cave water, springs, floodplains, and wetlands (bogs, marshes, and swamps)

Freshwater provides water for drinking, sanitation, agriculture, transport, electricity generation and recreation. It also creates habitats for a diverse range of animals and plants.

We cannot live without freshwater.
Map showing drainage basins for the major oceans and seas; grey areas are endorheic basins that do not drain to the ocean.
© en.wikipedia.org/wiki/User:Citynoise

The "shape" of freshwater

The rivers we see, the lakes we sail on, the swamps we get stuck in - they are where they are because of the physical geography surrounding them.
That physical geography forms what are called Drainage Basins.

A drainage basin is a region of land where water from rain or snow melt drains downhill into a body of water, such as a river, lake, dam, estuary, wetland, sea or ocean.

So a drainage basin includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels.

In essence, the drainage basin acts like a funnel - collecting all the water within the area covered by the basin and channelling it into a waterway.

Each drainage basin is separated topographically from adjacent basins by a ridge, hill or mountain, which is known as a water divide or a watershed.

Where is water?

Only 3% of the water on Earth is freshwater in nature, and about 2/3 of this is frozen in glaciers and polar ice caps.

Most of the rest is underground and only 0.3% is surface water.

Freshwater lakes contain 7/8 of this fresh surface water. Only a small amount in rivers.

The atmosphere contains 0.04% water.

Source: wikipedia

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