Total water on Earth is over 1 387 million cu km. but of these only 2.5% is fresh water sushi (pie chart). Composition of freshwater world presented in a cylindrical diagram. Really usable for a small part of the waters of rivers and freshwater lakes. Much of the same volume of fresh water is in maloosvoennyh and inaccessible areas.
Distribution of world's freshwater resources is uneven and depends on the geographical location of the territory and natural environment.
world's fresh water can not be increased, however, water consumption is increasing, the water becomes contaminated and unfit for use. Therefore, the planet has a problem of shortage of fresh water. Water scarcity has a regional character. He was particularly felt areas with dry climates, where resourced full runoff per capita of less than 5 thousand cubic meters. per year. Agriculture in these areas is only possible on irrigated land.
There are several ways to deal with water scarcity:
- reducing water consumption in agriculture;
-introduction of industrial low-water and waterless technology, closed-water (wastewater reuse);
- sea water desalination, water use icebergs;
- construction of reservoirs, river flow.
In a world built more than 60,000 reservoirs. The biggest of them are shown on the map.