A2 Geography- Water Conflicts
Terms in this set (19)
Geography of water supply and demand
71% of the earths surface is covered in water yet many parts of the world suffer from acute water shortage. Water is not evenly distributed over the surface of the earth and population growth, economic development and rising standards all increase the demand for water. In many parts of the world the demand is higher than supply.
According to the UN, more than 1 billion people lack access to fresh drinking water and this is having serious consequences for human well being. It is also a potential source of conflict between water users as well as between those countries and regions with water deficits and those with surplus supplies.
If the world is to ensure future water supplies, it will need to develop management strategies to resolve these conflicts. Achieving more sustainable use of scarce water resources is another priority.
Physical processes affecting water supply
The main source of water for human use are in the rivers, freshwater lakes and shallow groundwater and soil stores. This adds up to 0.296% of the total volume of water on earth; therefore freshwater is regarded as a finite source.
Global water supplies are linking to 3 main physical factors: CLIMATE, RIVER SYSTEMS and GEOLOGY.
Physical processes affecting water supply
Climate primarily controls how much water is stored in any of the earths natural reservoirs; the annual temperature and precipitation patterns in an area will determine the availability of water.
The amount of precipitation varies according to latitude. Equatorial regions receive the greatest rainfall , temperate regions are also comparatively humid, whereas tropical regions and polar regions are arid r semi arid. These are generalisations as other factors such as proximity to oceans and prevailing wind patterns distort simple latitudinal divisions.
Seasons also have an important role, for example, the monsoon lands of south east Asia have one very distinct wet season, while high mountains with snowpack hold vast reserves of water, some of which is released in late spring and during the summer.
In summer seasons, high temperatures tend to increase evaporation and plant growth increase rates of transpiration. This results in soil water stores often being used up in the summer and refilled in the winter.
Physical processes affecting water supply
The catchment area of a drainage basin collects all the precipitation within the area and channels it towards the coastline or a major lake. The relative sizes of the input (precipitation) and output (transpiration, evaporation and run off plus abstraction by people) vary hugely depending on the location of the drainage basin. The time it takes water that falls as precipitation to reach the main course of the river varies from a few hours to many years.
The LAG TIME (the time taken between the peak of a rainfall event and the peak discharge given at a point in a river) depends upon a number of factors such as:
Type of precipitation
Size and shape of drainage basin
Relief of the catchment area
These factors combine to determine the rate of discharge and the availability of water in any one place. River flow generally increase downstream as tributaries feed into the main river, though high temperatures can lead to considerable water loss by evaporation. Seasonal changes in climate can also create significant variations in discharge and produce distinctive RIVER REGIMES.
Physical processes affecting water supply
The nature of the rocks underlying drainage basin is very important as it affects the amount of underground storage. The permeability of the rock is crucial. Where the rocks are impermeable, water will remain on the surface as runoff, creating a high DRAINAGE DENSITY. Carbonferious limestone is PERVIOUS (water can flow through cracks and joints in it) and pass into underground drainage systems. Sandstone and chalk are porous and so contain pore spaces which can store water. The best stores known as AQUIFERS are sands and gravels which are bounded by impermeable rocks.
Human activity affecting water availability
Pollution caused by human activity and excessive abstraction of water supplies can further increase WATER STRESS. Pollution of groundwater is much less obvious than surface water pollution but is no less of a problem:
Sewage disposal in developing countries is expected to cause 135million deaths by 2020 (World Health Organisation). Diseases such as hepatitis, typhoid and cholera are common in areas with polluted water.
Chemical fertilisers used by farmers contaminate groundwater as well as rivers and can cause eutrophication.
Each year the world generates 400 BILLION tonnes of industrial waste, much of which is pumped untreated into rivers, oceans and other waterways.
Big dams trap sediment in reservoirs which reduces floodplain fertility and the flow of nutrients from rivers into seas. This may damage fish stocks and prevent beach formation, which in turn can expose coasts to greater erosion.
Abstracting water from rivers and groundwater sources can have unintended consequences
Water is being extracted form aquifers faster than it is being replaced. In arid areas, rainfall can never recharge these underground stores.
The removal of freshwater from aquifers in coastal locations can upset the natural balance of saline and fresh groundwater and lead to SALT WATER INCURSION and salination of wells and boreholes
Water supply and demand leading to water stress
As the global population grows and the demand for water increases, there will be less water per person. For water rich countries such as Canada and Brazil, this decrease is not a serious concern, but elsewhere it can be life threatening.
Globally, half a billion people, most of them living in Africa and the Middle East, are chronically short of water. There are insufficient renewable supplies of water in China and parts of Europe, while India looks set to suffer considerable water stress in the future. Even in the USA, where water is relatively abundant, availability will have halved between 1955 and 2055, most obviously in the dry South-West.
Agriculture is the major user of water, particularly as we struggle to increase food supplies for a growing population. Currently agriculture uses 2/3 of the ground freshwater supply, though this can vary greatly in different parts of the world.
For example, in Africa, agriculture uses 88% of water, compared with only 33% in Europe, where industry consumes more than half of the supply
The proportion of water used globally by industry is 22%, though this varies from 59% in high income countries to 8% in low income countries. The proportion rose relatively slowly during the 20th century, mainly in the developed countries of Europe, as well as Canada and the USA, however, it is expected that there will be a much more rapid rise in the coming decades due to the large scale industrialisation in countries such as India and China.
Water use in the home is the smallest category of consumption, using only 10%. Again, the amount used varies enormously from country to country. Most developed countries need at least 100,000 litres of water per person per year while most African countries the figure is less than 50,000 litres. Global domestic demand seems to be doubling every 20 years and it is arguably only the poor access in Africa that is limiting growth in demand.
Is the term used when the annual supply of water per person falls below 1,700m3
Is the term used when this figure drops below 1,000m3.
There a 2 types of water scarcity:
PHYSICAL SCARCITY- Occurs when more than 75% of a country or region's river flows are being used. 1/4 of the world's population lives in such area, which include parts of the USA and Australia.
ECONOMIC SCARCITY- Occurs when the development of blue water flow sources is limited by human and financial capacities. More than 1 BILLION people, in areas such as sub-Saharan Africa, use less than 25% of the river resources available.
Rapid economic growth in India and China is putting enormous pressure on water supplies.
INDIA has 4% of the world's freshwater but 16% of its population. Demand will probably exceed supply by 2020 as urban water demand is expected to double and industrial demand will triple. Hydrologists calculate that 43% of precipitation never reaches rivers or aquifers and water tables are falling rapidly as 21 million wells abstract water.
CHINA has 8% of the world's freshwater but must meet the needs of 22% of the world's population. 2/3 of Chinese cities do not have enough water all year round and national water supplies are likely to reach stress levels by 2030. China uses irrigation to produce 70% of its food, mostly in the North and North East, where the Yellow River and major aquifers are running dry. Huge engineering projects will soon transfer vital water to this area from the water rich South.
Not having the access to sufficient, safe water. Despite efforts to improve supplies and sanitation, there are 1.2 billion people without access to clean water, many of whom live in the 20 or so developing countries classified as 'water scarce'
Water insecurity (2)
In most developed countries, people are able to ensure a safe and secure water supply through investment in infrastructure, such as reservoirs and dams thought this can have a very negative effect on the natural environment. Less developed countries are being urged not to follow this pattern, tough large dams are often used as a symbol of progress and status, in spite of the evident negative impacts ob both people and the environment.
In Zambia, there was a proposal to implement some hard engineering water management on the BAROTSE FLOODPLAIN, with the plan being to drain the wetland and develop an irrigation scheme. Following analysis, it was shown that the economic benefits of the irrigation scheme would have been less than the benefits curently delivered by the wetland in terms of fisheries, agriculture around the floodplain, water supply, water quality etc.
Water insecurity (3)
HOWEVER, there are occasions where concrete infrastructure is required ,and this, in combination with soft engineering approaches, is crucial in order to improve water security worldwide. For developing countries, the outlook is bleak, as they simply do not have the money, nor the expertise, to invest in effective and sustainable water management.
Poverty and water poverty go hand in hand. Lack of water hampers attempts to reduce poverty and encourage development, whereas improved water supply and sanitation can increase food production, bring better health and provide higher standards of well being. Water wealth in developed countries brings cheap water, irrigation, energy and economic growth. Some say that water is 'the lubricant of development'.
Water Poverty Index
The index uses 5 parameters:
RESOURCES-The quantity and quality of surface and groundwater per person
ACCESS-The time and distance involved in obtaining sufficient safe water, not only for domestic purposes, but also for industry and agriculture.
CAPACITY-How well the community manage its water, including having the income to purchase water, as well as education about health and hygiene and how to manage water supplies
USE- How water is used in the home and by agriculture and industry.
ENVIRONMENT-Ecological sustainability (important to conserve the ecosystems etc. that are essential to support livelihoods)
Each of the parameters is scored out of 20, to give a maximum possible score of 100. This holistic approach to managing water can be used to determine priorities for action, and monitor progress towards targets.
Risks of water insecurity
Access to a clean water supply is fundamental to human health with vital implications for human welfare. The minimum requirement is about 5 LITRES PER DAY to prevent dehydration, but 30 litres a day is regarded as the minimum needed for cooking and cleanliness, as well as drinking. Contaminated water is a major health risk in developing countries, and water related diseases prevent over 2 billion people worldwide from leading healthy lives and undermine development efforts
Economic development and water supplies
Secure water supplies are also essential to economic development. They are needed to support irrigation and food production, manufacturing and energy generation. However, the development, extraction and use of water resources can lead to environmental and supply problems, and can have negative impacts on both economic activity and human welfare.