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treatise40297
| Water crisis
When there is not enough potable water for a given population, the threat of a water crisis is realized. The United Nations and other world organizations consider a variety of regions to have water crises of global concern.Other organizations, such as the Food and Agriculture Organization, argue that there are no water crises in such places, but steps must still be taken to avoid one. Causes of water crisis There are several principal manifestations of the water crisis. Inadequate access to safe drinking water for about 884 million people Inadequate access to sanitation for 2.5 billion people,which often leads to water pollution. Groundwater overdrafting (excessive use) leading to diminished agricultural yields. Overuse and pollution of water resources harming biodiversity Regional conflicts over scarce water resources sometimes resulting in warfare. Water scarcity's effects on environment Water scarcity has many negative impacts on the environment, including lakes, rivers, wetlands, and other fresh water resources. The resulting water overuse that is related to water scarcity, often located in areas of irrigation agriculture, harms the environment in several ways including increased salinity, nutrient pollution, and the loss of floodplains and wetlands. Furthermore, water scarcity makes flow management in the rehabilitation of urban streams problematic. Through the last hundred years, more than half of the Earth's wetlands have been destroyed and have disappeared.These wetlands are important not only because they are the habitats of numerous inhabitants such as mammals, birds, fish, amphibians, and invertebrates, but they support the growing of rice and other food crops as well as provide water filtration and protection from storms and flooding. Freshwater lakes such as the Aral Sea in central Asia have also suffered. Once the fourth largest freshwater lake, it has lost more than 58,000 square km of area and vastly increased in salt concentration over the span of three decades. Measurement of water scarcity Hydrologists today typically assess water scarcity by looking at the population-water equation. This is done by comparing the amount of total available water resources per year to the population of a country or region. A popular approach to measuring water scarcity has been to rank countries according to the amount of annual water resources available per person. For example, according to the Falkenmark Water Stress Indicator, a country or region is said to experience "water stress" when annual water supplies drop below 1,700 cubic metres per person per year. At levels between 1,700 and 1,000 cubic metres per person per year, periodic or limited water shortages can be expected. When water supplies drop below 1,000 cubic metres per person per year, the country faces "water scarcity". The United Nations' FAO states that by 2025, 1.9 billion people will live in countries or regions with absolute water scarcity, and two-thirds of the world population could be under stress conditions. The World Bank adds that climate change could profoundly alter future patterns of both water availability and use, thereby increasing levels of water stress and insecurity, both at the global scale and in sectors that depend on water. Ways to solve the water problem There are several ways to solve the water problem: construction of water reservoirs. In the world of 30 thousand. Reservoirs. However, large reservoirs have a negative impact on the environment: change the mode of groundwater affect the vegetation, occupy large tracts of fertile land, waterlogged surrounding soil, going trough the earth's surface by large reservoirs, increased seismic activity near major reservoirs in Asia, Africa, North America, etc. Interbasin transfer of river flow. Desalination of sea water. Transportation icebergs. жүктеу/скачать 5,96 Mb. Достарыңызбен бөлісу:
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