I - An unevenly distributed and unequally accessible resource
A – A vital resource unevenly available
- surface waters (Lakes, river basins – areas drained by a river and its tributaries);
- aquifers (groundwater reserves; groundwater – if they are close to the surface; fossil tables – if they can be renewed more);
- ice sheets (ice caps in polar regions) which are not operated.
- Arid and semi-arid areas north and South of Africa (Sahara, Kalahari), Central Asia (Gobi desert) and West of the Americas have low precipitation and suffer from water stress (water availability less than 1,700 m 3 per year per capita).
- However temperate, tropical regions (a dry season, a rainy season), Equatorial, monsoon regions (the tropical wind resulting from heavy rains and floods in summer), have sufficient or overabundant rainfall (floods, floods).
Access to water also depends on the available surface resources. The greater part of this reserve is stored in the Great Lakes. But the watersheds of major rivers, present on all the continents including in arid areas, are very important for human societies: the Nile, the Niger are thus real oasis in the desert.
B - A resource more and more requested but unequally accessible
- the growing population, and poor countries where water is not always well distributed, particularly drinking and of good quality;
- the constant increase in the acreage of irrigated farmland. Indeed, the needs in growing food, many States develop intensive agriculture. They increasingly use for irrigation allowing to increase crop yields;
- more a country develops, over its water requirements increase: it is the case of emerging countries and demographic giants such as China and the India. Due to their way of life and their economic development, the rich countries indeed consume more water than developing countries: in addition to their agricultural consumption, their urban, domestic consumption (drinks, showers, etc.), tourist and industrial (manufacture of energy, etc.) grow.
II – A controlled resource
A – Different types of facilities to meet the needs
B - These developments have created new landscapes
C – These arrangements are sometimes controversial
III – A resource coveted and threatened
A – The sharing of water causes conflicts
- With the proliferation of needs and activities, the pressure on water resources increases and different users are in competition, especially in the regions or water is scarce.
- Spain is a good example: it is a developed country that has increased its irrigated under greenhouses for export crops. These greenhouses are built in Andalusia, very touristy area with important cities. Summer, the tourism sector requires plenty of water (swimming pools, golf courses…). But water is rare and therefore over-exploited: in this province the issue of water sharing causes tensions between the different actors and different activities.
- The issue of water is often sensitive among those States which have to share the water of a river or groundwater. Each State has its own needs, it has tended to ignore those neighbours, unless they are more powerful.
- The countries upstream of the rivers (side source) are favored: the United States have built large dams upstream of the Colorado River and pump large quantities of water to power their irrigated crops and their major cities (Los Angeles, Las Vegas…). When the river passes the Mexican border, its flow is very limited, and it happens even more down to the sea.