Water resources management is essential, because water is vital. It is however unevenly available and accessible for the people of the world.
This situation poses a problem since needs grow with population growth and the increase in human activities.
Create effective facilities that ensure a good water supply across the planet while respecting the renewal of the resource is therefore a crucial goal.
I – An unevenly distributed and accessible resource
A – A vital resource unevenly available
Water covers 72% of the Earth’s surface, but 97% of this reserve is made up of salt water. Only 3% of the total can therefore be directly usable by humans.
This resource represents more than 40 km3 million divided between:
- 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.
Access to water depends on the cycle of the water and the very uneven distribution according to climate, precipitation.
- 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.
An important part of the world’s population also depends on groundwater, underground water reserves to live. These are less well known, but they represent more than 90% of usable resources.
B – A more and more requested but unequally accessible resource
Water balance is the ratio between the water needs of the population and the actual availability of the resource. It varies greatly depending on the region, because of the availability of the resource – which varies between lack and (over) abundance – and the unequal distribution of population densities.
Water demand increases, for three main reasons:
- 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
The increase of the water needs requires populations to achieve improvements to control the resource. These arrangements are more or less important and sophisticated according to the richness of the developers and the available resource type.
In arid and semi-arid areas formerly populated areas, the civilizations developed irrigation techniques. For them, the water control is vital. They have built dams to store water from rivers or drilled wells to draw water into the groundwater. They have also dug channels to bring water in the fields or in the villages. These are hydraulic civilizations.
These older methods have been repeatedly and modernized. The objective is to improve the storage, transfer and distribution of water to populations and activities that need. Large reservoirs dams were therefore built in the 20th century, first in the countries of the North, and in emerging countries today.
Systems of channels (of water) transfer water from storage areas to areas in a State of stress. These infrastructures can extend over hundreds of kilometers.
To distribute water in urbanized areas, it has directed water supply networks and improved irrigation sprinkler systems.
Finally, desalination plants transform seawater into drinking water.
B – These developments have created new landscapes
Populations have settled in areas where water was available and have transformed them, giving rise to new landscapes.
In arid areas, irrigation produced the oasis of greenery. Today, the use of spraying ramps creates water lilies in the desert. In Asia, men have manufactured landscapes of rice paddies, sometimes terraced. The huertas are irrigated in Spain perimeters. But other landscapes are linked to the developments in the polders, dam retention Lakes water…
In all cases, water is essential for human activities.
C – These arrangements are sometimes controversial
Policies for the construction of large dams are particularly controversial, because they cause important damage when retention lakes are filled.
The example of the construction of the dam of the three Gorges in China is representative: the commissioning of the dam resulted in the destruction of inhabited areas (displaced), archaeological sites and heritage (temples), but ecosystem drowned by the rising waters also.
But despite the criticisms, emerging countries have not abandoned this type of projects: they have growing needs in energy (hydroelectric dams produce electricity) and water to develop their activities.
III – A threatened resource
A – The sharing of water causes conflicts
Internal use 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.
International political conflicts
- 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 neighbors, 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.
In the regions of the world where strong tensions divided States, the question of water can trigger real ‘water wars’ (example: sharing the waters of the Nile or the Jordan in the Middle East). The United Nations has, since the 1950s, 37 conflicts related to water.
B – Water is also a threatened resource
Water resources are widely overused. This situation could worsen with the increase in needs and lead to a decrease in water availability. Some countries are already significant shortages in water, and their number is likely to strongly increase.
This situation is accentuated by the poor quality of some of the schemes: pipes with leaks, channels open in full desert zone where evaporation is important, spraying ramps spending more than what is necessary for crops water…
Water, poorly protected, is also polluted by agricultural, industrial and urban discharges… Excessive irrigation causes the salinization of land, fertilizers pollute the rivers and cause algal blooms on coastal areas (eutrophication).
In rich countries, wastewater is recycled in sewage. But these facilities are expensive and are rare in poor countries where water contaminated, causing health problems, kill many people every year (2.2 million deaths per year).
Water-related problems also reflect socio-spatial inequalities: in large cities in poor countries, the rich districts have water and sewage systems and pay the water cheaper than the people of the slums (that do not have running water).
C – How to protect water while ensuring the needs of the populations?
Many challenges must be overcome to sustainably manage water resources.
Need to ensure improved access to drinking water, the problem of the price of water (commodity like any other?). Indeed, major international companies are today organizing distribution of water, which requires many developments and investments. The economic shortage hampers the achievement of this objective in poor countries. However, access to drinking water is better today.
New techniques must be developed to limit the waste of water, in particular in agriculture (underground irrigation, drip), but also in consumer domestic urban (generalization of the reprocessing of waste water).
Fair trade wants to solve the problem of uneven trade by buying higher-priced products from small producers in the South. The objective is to improve their standard of living by a better income. Goods are sold more expensive in countries of the North, but avoiding intermediaries that would too raise prices.
Need to ensure to limit the pollution of rivers and aquifers.
All these issues require cooperation at the international level (unresolved question of « right to water »), at the regional level (to reduce pollution in the Mediterranean) and at the local level.
There not really global solutions, but solutions to individual cases.