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[6] [7] [8] This includes water in gaseous, liquid and frozen forms as soil moisture, groundwater and permafrost in the Earth's crust (to a depth of 2 km); oceans and seas, lakes, rivers and streams, wetlands, glaciers, ice and snow cover on Earth's surface; vapour, droplets and crystals in the air; and part of living plants, animals and ...
Fresh water makes up less than 3% of the world's water resources, and just 1% of that is readily available. About 70% of the world's freshwater reserves are frozen in Antarctica. Just 3% of it is extracted for human consumption. Agriculture uses roughly two thirds of all fresh water extracted from the environment. [1] [2] [3]
Some precipitation falls as snow, hail, or sleet, and can accumulate in ice caps and glaciers, which can store frozen water for thousands of years. Most water falls as rain back into the ocean or onto land, where the water flows over the ground as surface runoff. A portion of this runoff enters rivers, with streamflow moving water towards the ...
Rivers get their alluvium from erosion, which carves rock into canyons and valleys. Rivers have sustained human and animal life for millennia, including the first human civilizations. The organisms that live around or in a river such as fish, aquatic plants, and insects have different roles, including processing organic matter and predation.
The flow is then directed against the opposite bank of the river, which will erode into a more concave shape to accommodate the flow. The bank will still block the flow, causing it to reflect in the other direction. Thus, a bend in the river is created. [7] Rivers may run through low, flat regions on their way to the sea. [12]
An artesian spring is created when the pressure for the groundwater becomes greater than the pressure from the atmosphere. In this case the water is pushed straight up out of the ground. [7] Wonky holes are freshwater submarine exit points for coral and sediment-covered, sediment-filled old river channels. [8]
Stunning drone footage showcases the frost patterns that resemble flowers on a frozen lake in northwestern China.
The total volume of water in rivers is estimated at 2,120 km 3 (510 cu mi), or 0.49% of the surface fresh water on Earth. [2] Rivers and basins are often compared not according to their static volume, but to their flow of water, or surface run off. The distribution of river runoff across the Earth's surface is very uneven.