Did you know that water covers a staggering 71% of the Earth's surface? Approximately 97.5% of saltwater is held by oceans, and the remaining 2.5% is freshwater. Water is pretty much everywhere: above the Earth in both air and clouds, on the surface of the Earth in rivers, oceans, ice, plants and living organisms, and even inside the Earth, in the first few miles below ground.
The Earth's Water
On Earth, water is found in all 3 states of matter, namely:
| State | Location |
| Solid | ice in glaciers and snow at the North and South Poles |
| liquid | oceans, rivers, lakes, streams, and in the soil underground |
| Gas | water vapours, found in the Earth's atmosphere |
Water on Earth is found in:
- Oceans, seas, and bays
- Ice caps, glaciers, and permanent snow
- Groundwater
- Soil moisture
- Ground ice and permafrost
- Lakes
- Atmosphere
- Swamp water
- Rivers
- Biological water
In geography, a river is what is called 'running water.' It refers to a mass of water that flows over the land surface from its source and usually empties into the seas, lakes, swamps or depressions.
Water is essential for several reasons: it provides us with drinking water, it provides us with water for agriculture and it helps to control global temperatures.
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.
| Scarcity type | Meaning |
| Physical water scarcity | This means that there is not enough water due to physical reasons such as climatic reasons. This often happens in arid and semi-arid areas with low rainfall and a fluctuating river flow. An example is Northern Mali in the Sahara Desert. |
| Economic water scarcity | This means that a country has enough water, but it does not have the money to make it drinkable through processes like desalination and filtering. An example is certain parts of Afghanistan. |
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:
| Reason | Explanation |
| Rising population | we all need water to survive, and we use it for hygiene, cooking and cleaning. The increase in the global population means that more people need water, and this rise is putting a significant strain on an already fixed amount of freshwater that is available to us. |
| Economic development | Economic development - as countries develop, their water use increases. When people get wealthier, we see an increase in people using appliances such as dishwashers and washing machines, which use a lot of water. As more countries develop, the water demand will increase. Furthermore, we see that commercial agriculture, industry and tourism in so-called high-income countries (HICs) use significant amounts of water compared to low-income countries (LICs), giving the HICs a much higher water footprint. |
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:
- 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
- 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
Water Geography - Key Takeaways
- Water deficit, or water stress, 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 deficit, or water scarcity, is divided into:1. Physical water scarcity - not enough water due to physical reasons2. Economic water scarcity - enough water but no economic means to access it or make it safe to drink
- Water surplus is when countries have a water supply that exceeds water demands.
- Global water consumption is on the rise; there are 2 main reasons:1. rising population2. Economic development
- Factors affecting water availability:- Climate- Geology- Pollution- Over-abstraction- Limited infrastructure- Poverty
- 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.
References
- Fig. 2: Water distress by country map by the author using mapchart (https://www.mapchart.net/index.html) licensed by CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/)
Explanations 
Exams 
Magazine 
