Water Demand and Scarcity
In the past century the pressure on freshwater resources has increased dramatically. The world's population has almost reached 7.2 billion, and will pass 8 billion by 2025. On global scale water supply per capita has decreased by a third between 1970 and 1990. 700 million people in 43 countries suffer today from water scarcity, and it is expected that by 2025 1.8 billion people will be living with absolute water scarcity and two-thirds of the world population could live under water stress conditions.
Demand for water has tripled over the last 50 years and is always increasing, while growing pollution is likely to reduce the available quantity of suitable water. Before 2050, a quarter of the total average flow of all the rivers in the world will have been committed to use. Irrigated agriculture and hydroelectric power generation compete with other uses for water within national boundaries. At the same time maintaining the health of aquatic ecosystems and thereby preserving the services they provide is increasingly accepted as an essential concern to be addressed in water policy development and implementation.
Due to the uneven spatial and temporal global distribution of water resources, water scarcity has a strong regional and local connotation and is bound to affect human communities with different degrees of severity.
Floods and Droughts
Floods cause loss of lives, damage to property, widespread crop and infrastructure destruction and affect the economic development in many parts of the world.
As most of the increase of population and economic activities in the last centuries have taken place in flood plains, exposing people and assets to risk, the human and economic costs of floods are becoming more and more severe, particularly for less developed countries. The effects of climate change can also be added to the impacts of floods, though they are not yet clearly detectable in flood frequency and magnitude. Drought and desertification are also threatening human survival in many regions of the world, thereby increasing vulnerability and pressure on water resources.
For more information about floods, please visit the website of the Associated Programme on Flood Management (APFM), a joint initiative of the World Meteorological Organization (WMO) and the Global Water Partnership (GWP).
Internationally Shared Catchments
There are 263 trans-boundary lake and river basins covering nearly one half of the Earth’s land surface and accounting for an estimated 60 per cent of global freshwater flow.
A total of 145 States make up the territory within such basins, and 30 countries lie entirely within them (“Transboundary Waters” by UN Water), and competition for water among these nations could become a potential source of conflict. It is of paramount importance to ensure that activities in one part of a basin are not detrimental or harmful to actual or potential uses in other parts of the basin, implementing the principle of the basin as the natural geographical and hydrological unit for water management.
The global climate change scenario has the potential to impact the availability of water resources both in time and space. Climatic variability and change are increasingly affecting the water resources of most countries, and detected trends in streamflow are generally consistent with observed regional changes in precipitation and temperature since the 1950s.
Higher temperatures and changes in precipitation patterns as predicted by the Intergovernmental Panel on Climate Change (IPCC) will not only lead to decreased water supplies but also deterioration of the global ecosystem. These changes, as with the change in climate variables, will vary regionally around the globe, raising the risk of extreme events such as floods or droughts. Together with anthropogenic land degradation climate change is having a serious impact on the already fragile water resources across the globe. Impact studies at local and regional scales are needed to assess how different regions will be affected.
To respond to all these challenges, planning and decision-making on all water related issues must achieve new levels of sophistication, reliability, and acceptance at national, basin and regional levels. This demands timely, accurate and comprehensive data and information about the status of water resources to complement information about the economic, social, and environmental dimensions of water use.
Unfortunately, in many parts of the world the systems for collecting and managing water-related information are inadequate, and often are deteriorating. Particular difficulties include a lack of resources to maintain observing stations, even at basic operating levels, inconsistent standards and procedures for data collection, differing levels of quality assurance between agencies and countries, unreliable telecommunication systems and outdated systems for information management.
Regional and global cooperation must be improved in the gathering and dissemination of data and information, not only by reinforcing the technical infrastructure but also through the development of agreements providing the required legal framework to enable data exchanges between organizations.
This cooperation in the case of floods, droughts and other natural disasters is imperative if the global community is to reduce, mitigate and in some cases prevent the impacts of natural disasters.