Water Geography

The water cycle

The water cycle is the way that water moves around the planet (figure 1). Broadly, it follows a cycle of evaporation, condensation and precipitation. This is also known as the hydrological cycle.

The water cycle is made up of several processes, namely: evaporation, condensation, precipitation, runoff, transpiration, and evapotranspiration.

You can read more about all of these in our explanation of the Water Cycle.

Water Distribution on Earth

The world's total water supply is about 333 million cubic miles (mi³) or 1.386 billion cubic kilometres (km³). The water is either saline water (saltwater) or freshwater.

Water deficit definition - geography

The total water supply mentioned above is not evenly distributed across the globe. Some countries and regions experience a water deficit, also known as water stress or water scarcity. This happens when the water demand (far) exceeds the water supply. This can occur in areas with low precipitation, high evaporation rates, high population density, or any combination thereof.

Water scarcity can be divided into the following.

Water surplus definition - geography

On the opposite end, countries with a water supply that exceeds water demand have a water surplus. Countries and regions with water surpluses are usually located in temperate and tropical wet areas with high rainfall and lower populations.

Water Supply and Consumption

As mentioned earlier, not every country/region has access to public utilities, where we can simply turn on the tap to get water. Some of these places have to get their water from other sources, such as wells, or drums, like those handed out by aid organisations.

Water Supply Geography - Definition

By water supply in geography, we mean the provision of water by public utilities, commercial organisations, community endeavours, or individuals. A system of pumps and pipes usually accomplishes this.

Water supply system

A water system, or water supply system, is the infrastructure for collecting, transmitting, treating, storing, and distributing water. A water supply system usually includes the following components:

• Drainage basis
• Raw water collection point
• Water purification facilities
• Water storage facilities, such as reservoirs
• Additional water pressurising components, such as pumping stations
• Pipe network for water distribution
• Connection to the sewers

Water is essential as it provides drinking water and water to irrigate the land, which in turn provides us with food.

Global water supply

As mentioned earlier, different countries have access to varying amounts of water. Some general points are:

• Countries located along the Equator have enough water. This is due to warm, moist air that rises there, causing high levels of rainfall.
• Countries located to the north of the Equator tend to have physical water scarcity. Cooler, dry air falls there, and it is very arid. This means that there isn't enough rainfall.
• Countries located to the south of the Equator have some water scarcity, although usually less than those to the north. This is because countries to the south tend to span greater latitudes. Such countries usually have desert-like areas and rainforests. This means that water from the wetter areas can be transported to the drier areas. Australia is an example.
• Countries located furthest away from the Equator have enough rainfall to provide them with plenty of freshwater.
• Exceptions to the rules mentioned above exist in countries with high population densities, such as the UK, or countries where poverty causes economic scarcity, such as Nigeria.

Increase in water consumption

Global water consumption is on the rise. There are 2 main reasons for this:

This increase in water consumption can lead to water stress/scarcity (mentioned above). The image below (figure 2) shows the water stress per country in 2019.

Fig. 2 - water distress per country in 2019

Factors affecting water availability

As mentioned above, the global water supply is not evenly distributed. There are several reasons for this.

Climate

Low rainfall and high temperatures lead to water deficits, high(er) rainfalls, and low(er) temperatures lead to water surpluses.

Geology

Rainwater flows down to the rocks beneath the ground. Some rocks are permeable, meaning they allow water to flow through them, forming aquifers. This leads to less surface water. Other rocks are impermeable, meaning that they don't hold water, although they can trap it in the layers above.

Pollution

Even in countries that have access to enough water, pollution can lead to this water being unsafe to use. Mostly this happens due to untreated sewage and wastewater from factories. While groundwater is usually cleaner, pollution can still get into the ground, polluting the groundwater.

Over-abstraction

This is when water is taken from aquifers at a faster rate than it can be replenished again by rainwater.

Limited infrastructure

Water needs to be transported, which happens through pipes. To reduce leaks and pollution, these pipes need to be properly sealed. These pipes and laying them (buried in the ground) is expensive, and therefore not all countries/regions have these pipes in place.

Poverty

This is a big problem in certain countries. When people do not have access to clean, safe water, they will become ill. This means that they cannot work and earn money. They are locked in what is called a 'cycle of poverty,' where 1 issue leads to another, and so on.

Water Table Definition - Geography

The water table is an underground boundary between the soil surface and the area where groundwater saturates between sediments and cracks in rocks. At this boundary, both water and atmospheric pressures are equal. The water table is also known as the level of groundwater.

Above the water table is the soil surface. This is called the unsaturated zone, or 'zone of aeration,' which means that it contains earth and air.

Underneath the water table is the saturated zone. This is where water fills all spaces between sediments. At the bottom of the saturated zone is impenetrable rock.

The water table is a fundamental reference surface in the study of groundwater. In a hilly landscape, the water table is usually at greater depths below the surface than below valleys.

Two main things influence the water table:

1. Fluctuations by changes in precipitation, usually coincide with the seasons. This means that the water table is higher during winter when precipitation is higher, and lower during the warmer, drier months of summer when precipitation is low
2. Human extraction of groundwater (by wells) for drinking water and land irrigation

Water must be extracted sustainably otherwise, the water table can drop permanently, causing groundwater depletion. Groundwater depletion happens when the groundwater is extracted at a higher rate than precipitation can replenish it. Countries that are currently experiencing water depletion are India, China, and the US.

Water Management - Geography

In simple terms, water management is the control of water resources to minimise damage to life and property to maximise efficient, beneficial use. (Check out our explanation on Water Supply Management to learn more!)

While that sounds simple enough, in practice, it is more complicated. Water scarcity is already becoming a major problem due to 2 converging phenomena: the growing use of freshwater and the depletion of usable freshwater resources.

Water management methods

It has been estimated that the global use of water has grown more than twice as fast as the population in the last century. An increasing number of regions are reaching the limit at which their water services can be sustainably delivered, and it will only get worse.

At a global level, 31 countries are already experiencing water shortages, and by 2050 there could be 48 countries facing shortages. According to an estimation by the UN, by 2050, 4 billion people will be seriously affected by water shortages.

Not only will those shortages affect people in terms of having access to (drinking)water, but shortages will also cause conflicts between countries/regions over access to water resources and the sharing of water.

To try and prevent these shortages, water (resource) management is needed, which is the activity of planning, developing, distributing and managing the best use of water resources. Different methods can be used:

• Rainwater harvesting (RWH)
• Groundwater recharge
• Artificial groundwater recharge
• Drip irrigation
• Greywater
• Sewage water treatment
• Conjunctive use
• Aquifer storage and recovery (ASR)
• Desalination

If you want to know more about this, check out our article on Water Supply Management.