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Factors affecting water availability

There are several reasons why global water supply is not even. Access to a fresh water supply is affected by the following factors.

Climate

Low levels of rainfall and high temperatures lead to . When rainfall is low, there is less water available. When temperatures are high, water evaporates and so there is less available to use. are common where rainfall is high and temperatures are lower.

Geology

Rainfall flows down to the rocks beneath the ground. Some rocks are and allow water to flow through them. Permeable rocks can lead to less surface water. For example, limestone landscapes often have dry rivers - the rivers only exist when rain has just fallen. Permeable rocks form , which mean they are stores of water. 70 per cent of the water supply in the south east of England comes from the chalk aquifer beneath the surface. Other rocks are . These rocks do not hold water, but they can trap it in the layers above.

Pollution

Some places have plenty of water, but pollution has made it unsafe to use. Untreated and waste water from factories cause problems. is usually cleaner, although pollutants can travel down into the ground. Gold mining near Johannesburg, South Africa, has led to uranium, arsenic and sulphuric acid polluting streams and rivers.

Over-abstraction

When water is taken from aquifers, groundwater levels fall. If the amount of water taken is greater than the amount of water falling as rain, it is called . The Sonoran Desert in Arizona has experienced over-abstraction as water is taken for irrigation and urbanisation. The land here is and water is becoming scarcer.

Limited infrastructures

Pipelines are needed to safely move water from place to place. Sealed pipes reduce the potential for leaks and pollution. Some places do not have these pipes in place. They can be expensive to lay as they need to be buried underground. Water pumps also form part of the water . Water pumps in villages across Kenya were recently fitted with that send text messages if the devices break down.

Poverty

Nearly 1 billion people in Africa do not have access to clean, safe water. This locks them in a - they cannot afford water so they become ill and when they become ill then cannot work and earn money.

Politics

Communication needs to take place within countries and across borders. There needs to be cooperation between states for the use of water resources that cross international borders. If, for example, water is polluted in one country then this will affect all other countries downstream.

Water politics, sometimes called hydropolitics, is politics affected by the availability of water resources. The River Nile, for example, is the primary water source for both Egypt and Sudan. The Nile is classed as an international river and flows through nine countries before reaching the Mediterranean Sea.

Impacts on water insecurity

Water security is when the entire population of a country has sustainable access to adequate quantities of acceptably clean water. There are several impacts of water insecurity. Some of these impacts are linked in a cycle of poverty.

Lack of clean piped water

Many girls across Africa spend hours walking to collect water rather than attending school.

Waterborne disease

Drinking or using dirty water puts people at risk of and illnesses, such as diarrhoea, and schistosomiasis. Schistosomiasis is an illness caused by a parasitic worm that enters the body through the skin coming into contact with water that contains untreated sewage. It has been reported in 78 countries and 90 per cent of people receiving treatment for it live in Africa.

Food production

Water insecurity can lead to lower levels of food production. can increase crop yields by as much as 400 per cent. Places that do not have enough water to irrigate crops have less food to eat.

Industrial output

Industry needs water for all stages of production. Water is used as a , a coolant, a method of transport, and in some cases, a source of energy. Areas that experience water insecurity are unable to operate factories and make products. This leaves them relying on imports, which may be expensive.

Conflicts

Water is a source of conflict in some parts of the world. Seizing is a powerful way of controlling water and hydroelectricity supplies.

Aerial view of a large concrete structure infront of a large body of water with mountains in the distance
Image caption,
The Mosul Dam in Iraq