The Effects of Overpopulation on Water Resources and Water Security
If projected withdrawals to meet population growth exceed the ability of the water sources The impacts of future populations on the amount and quality of water. Impacts of population growth and economic development on water quality of a lake: case study of Lake Victoria Kenya water. Juma DW(1). Quantitative supply and water quality problems are mounting and could .. The semi-arid areas of the continent, with their high populations in relation to water.
Many people have said that the forests around the world act as the lungs of the world.Water Pollution and Population
Without them, the carbon dioxide levels will rise and this will lead to other environmental complications that could end up being irreversible.
Furthermore, as the population continues to grow, more technologies and practices will be implemented to increase agricultural yields.
As humanity continue to use these waste products, it will increase dead zones in pools, lakes, and rivers. With the increase of dead zones, fishes and other marine organisms will start to die more frequently. This will lead to cascading events that will negatively impact the marine environments and the quality of water. Population Growth can also negatively the atmosphere. With more people being born and living the cities, the level of carbon dioxide CO2 emissions increase also.
This will result in more heat that gets trap within the atmosphere, and this is a factor that contributes to global warming. Air pollution is also destroying the ozone layer.
Without the ozone layer, harmful radiation from the sun can penetrate to Earth. This could possibly lead to skin cancer for humans. Air pollution can also impact human health. Urbanization, in particular, through increased population density and the concentration of demand, can make the latter a serious constraint on local resources. Many third world cities are critical areas from the viewpoint of water supply see Annex 1. Problems are especially acute when urban growth is based on the migration of rural poor rather than on economic growth.
The magnitude of the requirements brought about by population growth and urbanization is revealed by the extent of unmet needs. Despite an international effort to promote the development and implementation of water and sanitation plans under the International Drinking Water Supply and Sanitation Decade, progress at the end of that period still was inadequate.
The number of people lacking access to clean drinking water had been reduced by one third, but still stood at more than 1. Relatively greater progress had been registered in rural areas, where the number of people in need had been reduced from 1. But the rural population still lagged behind the urban 37 percent unserved against 18 percent.
As to the number of people lacking access to adequate sanitation services, it was unchanged at 1. More than half of the rural people were affected against 28 percent of the urban. Globally, making substantial progress on the urban and rural water supply front would require a tripling of investment over s levels.
The bulk of investment in water supply and sanitation so far has been directed to the urban sector and the better-off population, with persisting inequalities as a result. In principle urban concentrations should enable economies of scale, but growing numbers can be overwhelming. Human beings need only about 5 liters of water each day for cooking and drinking; according to WHO, however, good health and cleanliness require a total daily supply of about 30 liters per person 11 cubic meters per year.
By comparison, regional levels of per caput withdrawal for domestic and municipal usages are estimated as follows: This being said, basic needs are sometimes abundantly covered, indicating a variable amount of wastage, particularly in developed regions.
It is a fact that access to stable and easy supply--in particular water on the tap in urban settlements-- stimulates use considerably. Globally, water withdrawals for domestic and municipal usages account for a modest part of the total: But they are growing rapidly. Bywithdrawals are expected to double with respect to their level and to reach 11 percent of total use see Annex 3.
Population growth, especially that which will occur in third world cities, would be responsible for a substantial part of this increase. In developing countries irrigated areas represent 16 percent of all cropland and provide 37 percent of the production- -implying a productivity three times as high as that of other lands.
Irrigation and improved seed varieties were the basis of the "green revolution" which made most of Asia self-sufficient in food. But water requirements for irrigation are extremely high in comparison to the output: Depending on the crop and the location, producing one ton of cereal requires between and tons of water wet paddy being the most wasteful.
Since one ton of cereal covers the annual consumption of about four persons on a world average, it can be estimated that the average consumer of irrigated cereals thus indirectly uses about tons of water per year--to be compared with the few tons per caput required for domestic use.
Indeed, agriculture is the major water user world-wide: Regional levels of water use by agriculture on a per caput basis are the following compare with the levels of domestic use above, calculated from the same source: Globally, irrigated areas have increased from about 50 million hectares in to million in and more than million now, mostly to respond to growing third world needs.
Recent projections of agricultural demand to are shown in Annex 4. The role of population growth in the projected increases in demand can be estimated from these figures, as follows: Respective shares of the growth in: In addition, more than 17 million hectares of existing irrigation schemes will need to be upgraded; small-scale water programmes and conservation actions will be needed on 10 million hectares in rainfed areas.
To enable this expansion of irrigation, water withdrawals are projected to increase by about 17 percent globally.
According to the projections of Annex 3, water use by agriculture is expected to grow rather slowly if compared to other usages about one percent annually but the additional requirements will be very large in absolute terms: This will create severe competition between sectors in regions with limited water resources and a potentially growing industry. Irrigated areas will not expand again at rates comparable to that of world population growth as they did in the s and s.
This is partly due to the ever scarcer availability of hydrologically favourable sites. These natural conditions increase the costs of irrigation development. The need to adopt preventive measures against irrigation-induced land degradation compounds this factor. This, in combination with the frequent social, health and environmental costs, has actually discouraged lending, at least for large-scale irrigation. In the medium term, population and economic growth will exert even greater pressure on water resources than on land.
Africa and Asia already suffer from diminishing per caput water supplies, and many countries already are closer to their water resource limits than to their land limits. This category of needs is rapidly increasing. Population growth contributes to that increase, although in a minor way: Per caput water withdrawals for industrial usages are estimated as follows: The fastest growth is expected to take place in Africa and South America, but the largest absolute increases by far will be in Asia.
The lowest levels are found in poor developing countries, mainly in Africa. The highest levels are found in a few countries with high ratios of irrigated land per caput Iraq, Pakistan and central Asian Republics of the former USSR. In the second half of this century water withdrawals increased between and 4 and 8 percent annually.
Water use is still growing in the developing countries, but stabilizing in the industrial countries. As a result, global withdrawals are expected to rise at only 2 or 3 percent annually during the s.
Yet supply problems will keep mounting: Water demand patterns of the future will be characterized by growing competition between sectors, especially in developing countries. That competition will be particularly intense around the cities, where the demands of households, industrial plants and agriculture will inevitably put increasing stress on water just as on land.
If rural users are deprived of water resources in the process, this will accelerate migration to the cities. In the developed world, use levels are stabilizing; water- saving modalities of use and water re-use are gradually expanding as the costs of water supply and treatment are better charged to users.
In developing countries the margins for increased demand are considerable, on account of rising industrial sectors, unmet domestic and municipal needs, and agriculture. The former consist in modifications to the circulation of water and its quality by withdrawals, waste water disposal, river regulation etc. The latter consist in modifications of vegetation and soil cover: Disturbances of water flows in turn affect the wetting of the soil, the recharge of aquifers and rivers, the quality of freshwater and the per caput availability of water.
Deforestation is a major factor of changes in watershed dynamics. Forest areas tend to have more stable patterns of river runoff, because the catchment capabilities of the forest ecosystem enable a higher amount of groundwater discharge.
Deforestation therefore causes significant changes in river flow patterns, with accelerated runoff and lost storage, in turn causing a higher occurrence of flooding in wet seasons and a greater likelihood of dried-up rivers in dry seasons. Population growth is an important factor often overshadowing logging operations in deforestation, through the needs for more cropland and wood. Examples of this are numerous.
The following is a typical description: Ethiopia, "which has only 6 percent of its forest cover left, is bleeding its topsoil into rivers at the rate of tonnes per square kilometer per year".
Such is the disturbance brought about by loss of forest cover that it can cause water scarcity even in places with very abundant rainfall. Damage becomes reciprocal when forests are affected by water disturbances: Other actions leading to land degradation such as overexploitation or overgrazing have analogous effects on water regimes. The diagram in Annex 5 illustrates, inter alia, such processes. Urbanization--a major demographic trend all over the world-- also has distinct effects of surface water.
When streets and other impermeable surfaces replace permeable soils and vegetation, the volume, velocity and temperature of local runoff are increased, reducing the base flow of rivers during dry periods. It also is a primary resource when surface water is scarce. During the recent decades it has supplied much of the water needed for burgeoning cities as well as for irrigation development.
But groundwater aquifers are replenished only slowly, and human demands often exceed the natural recharge see Annex 6. In Tamil Nadu, heavy pumping for irrigation has caused drops in water table levels of meters in a decade. Pumping in Beijing exceeds the annual sustainable supply by 25 percent; in northern China, with heavy agricultural, domestic and industrial demand, water tables are dropping by 1 to 4 meters per year. In the Bangladesh lowlands, the mining of groundwater for irrigation has brought about seasonal declines of the water tables; in the dry season, most village handpumps the essential source of domestic water go dry.
Overpumping of underground aquifers can cause soil subsidence. Third world urban areas such as Bangkok, Beijing or Mexico City are affected: The phenomenon also occurs in rural areas as in various areas across the southern USA.
How does Population Growth Affects the Environment Sustainability?
Overpumping also causes a particular type of pollution in coastal urban areas where the depletion of the aquifers fosters the intrusion of saltwater: Freshwater is increasingly polluted by organic nutrients, toxic metals, and agricultural and industrial chemicals, carried by industrial effluents, land use runoff, and domestic wastewater. Secondary but growing sources are the leaching from mine tailings and solid waste dumps, and atmospheric deposition of pollutants into water bodies.
To the traditional concerns of pollution from organic wastes and the salinization of irrigated areas, have gradually been added those of suspended solids, heavy metals, nitrates, radioactive wastes, organic micropollutants and the acidification of lakes and streams.
Too often, industrial liquid wastes are dumped in contravention of regulations, toxic and hazardous industrial and commercial wastes are disposed of in water bodies or land sites, and systems to dispose of waste water and control flooding are inadequate. It is estimated see Annex 3 that 42 percent of the water in domestic and municipal usages is returned to the water cycle, accounting for 11 percent of total waste water.
Rapid urban expansion of the recent decades "has increased the pressures on the urban environment and on surrounding regions and their natural resources. It has created immense and growing problems of air and water pollution [ From 30 to 50 percent of urban solid waste is left uncollected.
The implications of all the above for the globe's shrinking supply of freshwater, the health of urban residents and the integrity of the globe's atmosphere are obvious". Much of the pollution arises from the rapid growth of squatter settlements on the periphery of cities--many of them springing up on low-lying land and along waterways, and their wastes flowing into urban water sources.
How does Population Growth Affects the Environment Sustainability? – Environmental Sustainability
The poor are the most affected by the deterioration of the physical and natural environment, both the victims and unwilling agents of environmental damage. Most of the water used by industry 87 percent according to the estimates of Annex 3 is eventually returned to the water cycle, making up 47 percent of total waste water. It is often polluted by chemicals and heavy metals; often, also, its temperature is increased to the detriment of life support systems downstream.
In most developing countries pollution controls, when they exist, cannot keep pace with urbanization and industrialization. In some large cities, the daily outpouring of industrial wastes into water bodies reaches millions of cubic metres". Things are better in developed countries, but even there problems exist, particularly in non-OECD countries where controls on industrial effluents are inadequate. While industries and domestic sewage are the main sources of pollution in developed countries, agriculture plays a bigger role in developing countries due to the clearing of land, the use of fertilizers and pesticides, and irrigation.
The demand for range- and farmland is a major factor in deforestation. The resulting accelerated runoff in turn accelerates erosion: Soil erosion in deforested watersheds increases water turbidity and accelerates the leaching of soil nutrients.
These effects are particularly severe in tropical regions, especially during the rainy season; but other regions are not immune. Irrigation returns only a quarter of its withdrawals to the water cycle but this return flow accounts for 42 percent of total waste water.
The combined increases in irrigated areas and related use of fertilizers and pesticides in developing countries have heavily polluted irrigation return flows, with significant threats to the aquatic environment as chemicals run off into streams or percolate into groundwater.
Urban areas have a high risk of water pollution. Runoff from streets can carry oils, heavy metals, and other containments, while sewage water can leak into ground water, bringing bacteria, nitrates, phosphorus and other chemicals. Waste dumping also can pollute existing sources of freshwater with hazardous materials and toxic chemicals.
It is estimated that between forty to fifty percent of all available freshwater sources on earth are polluted Living Lakes Partnership.
The combination of the expected substantial increase of people residing in urban areas and the preexisting dangers of water pollution in urban settings, will lead to a rise in the amount of water that is not potable due to pollution. It is imperative that infrastructure to limit freshwater pollution is invested in in the future, by both developed and underdeveloped nations.
Finally, the pressures that are put on water resources by overpopulation will lead to civil and international conflict over control of available quantities. Accounts of battles and fights over water resources dates back to BC, when Assyrians would poison, divert, and destroy water supplies in order to put their enemies under siege Pacific Institute.
Since the yearthere have been at least over one hundred and ten major conflicts over water resources either between nations or within one.
Population and Water Resources (contrib. by FAO)
Middle Eastern countries, such as Iraq, Iran, Afghanistan, Yemen, and Syria, countries in Africa like Darfur, Sudan, and Somalia, and the South American countries of Peru and Brazil have all experienced armed struggles involving scarce water supplies. These armed conflicts are due to multiple countries relying on a single water source, such as the Shatt al-Arab river between Iran and Iraq.
A dispute over water withdrawal from the river was an important factor that caused the Iran-Iraq war in Pacific Institute.