Search for:

Guest blog: More water storage needed for a sustainable future

Global declines in water storage are increasingly troubling. With greater hydrological variability due to climate change, more storage will be vital to provide the same level of security of water, food, and energy. Water storage is fundamental protection from the impacts of a changing climate, safeguarding the supply of water, and the water–food–energy nexus, even during extended drought.

Wyaralong Dam

For thousands of years, dams have stored water to irrigate crops, control flooding, and more recently to supply water for industrial and household use, and generate hydroelectric power – contributing enormously to food security, human development, and economic growth.

These days, many dams serve more than one function but remain the primary mechanism for coping with the variability of water supply and demand. During the last century, more than 45,000 dams higher than 15 m have been constructed worldwide, creating a combined storage capacity estimated to be between 6,700 and 8,000 km3, representing 17 percent of global annual runoff.

Security of water, food, and energy are inextricably linked. For example, approximately 50 percent of all large dams worldwide are used for irrigation. Without sufficient water storage, irrigated agriculture (the largest user of water at the global level, contributing 40 percent of the world’s food) is at the mercy of changing patterns of rainfall and runoff.

Understanding water storage issues is essential for successfully managing water resources. At the simplest level, it is a matter of ‘inflow (water supply) less outflow (water demand) equals the change in storage’. But it is particularly important to understand whether storage declines relate to reducing supply, increasing demand, or both. The answer is both and more.

Key factors influencing storage are greater variability of inflows due to climate change, increased demand due to population growth, reduced net storage due to sedimentation, and less dam construction occurring worldwide due to environmental and social impacts.

Climate change

The effects of climate change are predicted to increase and to result in greater magnitude and frequency of hydrological extremes, such as prolonged droughts and significant floods. With the prolonged drought, inflows to storages will reduce. If demand remains the same, stress on existing water storage will increase.

In a 2015 report, the Climate Council of Australia stated that Australia is the driest inhabited continent on Earth, with some of the world’s most variable rainfall and stream-flow. The country has been deeply affected by drought throughout its history, with the most recent being the ‘Big Dry’ of 1996–2010 (also called the Millennium Drought) which went down in history as one of the worst droughts on record for Australia, with devastating impacts.

This prolonged drought ended in some areas of Australia with major flooding. In the state of Queensland, flooding began in December 2010 and continued into 2011 with at least 90 towns and over 200,000 people affected. The final damage was estimated to be USD 2.38 billion.

Storage can help protect communities from the impacts of these extreme events.

Population growth

It is estimated that in 2017 Earth supports around 7.5 billion people, yet 200 years ago the number was less than 1 billion. Population and water demand are strongly linked. With our world population increasing at around 80 million people per year, rising demands for basic services and growing desires for higher living standards will intensify the demand for water and put additional strain on existing storage.


Many of the larger reservoirs worldwide have had their lifespans reduced significantly due to deposits of sediment within the storages, diminishing net storage in many regions of the world.

A number of these reservoirs were designed for 50-65 years of functionality until sediments would reduce their operational capacity. Although in these cases the reduction in storage was expected, it still results in a reduction in total storage, and therefore requires a response.

Globally, the annual rates of loss relative to installed storage capacity are generally estimated to range between 0.5 and 1.0 percent, equating to a total worldwide loss of storage of around 40 to 80 km3 per year.

Reduced dam construction

Installation of large reservoirs peaked during the 1960s and 1970s, both in number and storage volume. However, some of these larger reservoirs caused significant environmental and social damage, bringing dam construction under great scrutiny and ultimately decreasing dam construction worldwide.

With less dam construction, some decommissioning of older dams, and loss of storage due to sedimentation, net storage worldwide is falling, most dramatically in storage per capita. Such reduction in storage is likely to undermine the reliability of supply.

graph - water storage - Entura

Few kinds of development projects arouse as much controversy as dams. However, large dams vary considerably in their environmental and social impacts. The severity of environmental impact is largely determined by the dam site. While dams at good sites can be very defensible from an environmental standpoint, those proposed at bad sites will be inherently problematic even if all feasible mitigation measures are properly implemented. The challenge is to find good dam sites to enable these necessary water storage to be developed.

It is important to note that the 2000 World Commission on Dams Report marked a new focus on sustainability in the development of dam engineering projects, requiring the participation of affected communities in the project planning phase.

How can we take action?

Good site selection is the most effective environmental mitigation measure.”

The following actions form a useful response to reduced worldwide storage and the pressing need to increase water storage to maintain reliable water supply, irrigation, and energy systems in a changing climate:

  1. Prioritise managing existing storages well, and recognise the importance of storages for maintaining reliable supply. Appropriately manage sedimentation and its impact. Employ near-real-time management of water based on improved information systems to ensure the best economic use of existing reservoirs
  2. Explore opportunities to increase the storage capacity of existing reservoirs by raising dams. Often, this can be more cost-effective and have lower environmental impacts than a new dam project. It may also be possible to improve the use of existing storages by providing greater interconnection between

Water reservoirs save lives and create value

While there is considerable opposition to dams and reservoirs in the Western world, reservoirs built to store water during the rainy season so it can be used during the dry season can save lives and secure values when the rains fail.

East Africa is in the grips of a devastating drought, an unfortunate and all-too-common tragedy. Crops are failing, and both livestock and people are dying from lack of access to food and drinking water. While there is considerable opposition to dams and reservoirs in the Western world, reservoirs built to store water during the rainy season so it can be used during the dry season can save lives and secure values when the rains fail.

How reservoirs work

Water reservoirs allow us to even out the differences in water availability between dry and wet seasons. Too much water in the wet season can cause floods, or too little in the dry season can cause droughts, both of which pose obvious problems for the people who are affected. The tropical region of East Africa may even receive enough rain during the dry season, but the problem is the duration and distribution. High-intensity rain may last for only a short period, generating floods. The water is also lost without people being able to use it.

Norway has been building hydropower installations for more than 100 years. This hydropower plant on the Nidelva River is just south of the Trondheim city center. Photo: NTNU

A region may have enough water as seen from an annual perspective, but may nevertheless experience periodic water shortages and restrictions in use, as the natural supply may be unevenly distributed over the year. The larger the difference between periods of limited water and periods of too much water, the more storage is needed. Water reservoirs smooth out these differences in water availability. A country’s water security can be described by the capacity it has to store excess water, compared to natural variations of runoff throughout the year.

Norway has developed storage capacity to ensure hydropower production throughout the winter when the natural runoff of water is low. In other areas of the world, dams and reservoirs can provide water for irrigation or drinking water, particularly where the rainy season lasts from 3-4 months and provides an abundance of water, followed by an 8-9 month-long dry period. At an international level, flood control is also one of the main reasons to build reservoirs, often in combination with one or more of the other aforementioned goals.

Drought and the development of reservoirs in East Africa

The eastern parts of Kenya and parts of Somalia are especially affected by the current severe drought. The infrastructure in this region is quite limited and poorly developed in terms of water storage. Nor is there any connection via channels or other delivery systems to areas with more abundant water resources. This kind of infrastructure would have reduced the region’s vulnerability to drought.

When parts of Ethiopia were affected by drought in 2015/2016, it was similar to the 1980s, when Bob Geldof organized the “Live Aid” concert with his musician friends, bringing an outpouring of support and focusing the whole world’s attention on the problem. Studies from NTNU in Norway, supported by an analysis from Ethiopia, suggest that a reasonable development of reservoirs and diversion channels for irrigation in the drought-prone parts of Ethiopia can save lives and value the next time drought strikes this area. When the Ethiopian drought finally ended in the spring of 2016, the same area was tragically hit by heavy rains and floods. People died in the flooding and landslides. Water reservoirs would have most likely reduced this problem.

The World Bank confirms that a steady and secure supply of water can support economic growth in Ethiopia. Ethiopia is currently building many reservoirs to improve its food and energy security. The country has great ambitions to become East Africa’s powerhouse. However, the larger reservoirs are on the Blue Nile, which flows towards Sudan and Egypt, and south on the Omo Ghibe River system, which drains into Lake Turkana in Kenya. Neither of these areas experienced the 2015/2016 drought.

Egypt controls the water

The relationship between the availability of water storage capacity and the problems posed by drought has been comprehensively documented. One commonly cited case that illustrates this relationship is the Aswan Dam and Lake Nasser reservoir, which help protect Egypt from drought and food shortages. Researchers have documented how Egypt managed droughts in 1973, 1974, 1983, and 1984 because of the country’s ability to store water. Ethiopia suffered great human and material losses during these same years. It is hard to imagine that the authorities in Egypt would be able to supply a population of more than 80 million people with food without Lake Nasser. In addition, Egypt has benefited greatly from the ability to generate power while reducing flood risk along the Nile River.

he California drought

What about the 2012-2015 California drought? Many of California’s rivers are strongly regulated and the state should be better prepared than Ethiopia, for example. Reservoirs made it possible to store and allocate the little water that came as rain or snow in the best possible way, reducing damage to agriculture, private households, and ecosystems. The end of the drought was followed by heavy rainfall, filling most of the state’s reservoirs to average levels or higher. At the same time, a damaged spillway at Lake Oroville caused the state to urge nearly 200 000 people to evacuate because of fears that there would be an uncontrolled release of water.

Heavy rainfall and snowmelt caused damage to the spillway and created a dramatic situation in California. At the same time, if the Lake Oroville reservoir had not been in place, downstream areas might have suffered great damage, because the reservoir gave the state the ability to capture and regulate the large natural flood.

Reservoirs reduce damage during floods

The United Nations considers floods to be the natural disaster with the greatest potential …

The benefits of using water tanks

Why save water in water tanks?

The earth is a unique planet. Unlike any other nearby planet, the earth has water. In fact, the earth is covered by around 70% water. With all of this water, one might wonder why saving water, by using water tanks, for instance, is so important, why it is a constantly talked about issue.  The big issue revolving around water shortages is that while we have so much water, we can only consume around 2.5% of it. Our planet is mostly covered by saltwater. And what makes things even more difficult when it comes to water for human and animal consumption is that most of it are trapped in glaciers that need to remain iced to maintain the earth’s climate.

So water is a tricky subject and you can understand that saving water and storing water is a very important duty that we all need to do. While we cannot always help to prevent leaks in water pipes that belong to the local water supplier, there are benefits to installing a water tank to collect water.

Different size Water tanks from Rainbow Tanks
Water Tanks

Advantages of having water tanks

Save money

Water is a precious commodity and it is in scarce supply.  Steel Water storage tanks will enable you to collect rainwater and even surface runoff for use in the garden or to clean with. There are many water treatment options these days that will enable you to purify the water that you have collected and use it for washing dishes and clothing. Rainwater can be used to water the garden when the need arises, and it can also be used to wash the car.

Water tanks reduce flooding

Flooding happens when the natural water table can no longer hold all of the water that is bearing down on it. When this happens the water sits on the surface and the constant moisture can lead to landslides or flooding damage. By installing a water storage tank the water that would usually end up sitting on the surface will now be stored in a tank and used when needed.

Having water during a crisis

In South Africa, we are susceptible to droughts and other major water shortages. Having a water storage tank is going to enable you to have a constant supply of water even during those times when there are droughts. This water can always be purified and used for other purposes later on.

Water tanks for agricultural use
Water tanks for agricultural use

Farming irrigation

Keeping a farm irrigated can be a financial nightmare especially since the farm will require many liters of water to keep the plants lush and healthy. Farmers rely heavily on the rainy seasons to ensure that their crops flourish so that they have a harvest at the end of the season. If there is a period of no rain then the crops can either die or they will lose their health. When using rainwater you will be able to save money by using the roofs of your structures to capture the runoff. The water that would normally run off the roof and be wasted on the ground will now be captured in the tank and stored for use in the irrigation of crops and other produce.

Non-drinking uses

Water is not only used for consumption by humans and animals. You can save money by using the water to flush toilets, wash clothing, water the garden, and even clean the house.

Water storage tanks are made from materials that cannot break down and contaminate the water that they hold. They have a long life span and can be used again and again over a number of years.

Why should you be saving water?

  1. Without water there would be no plants, animals or humans. Water is a life fluid and it needs to not only be conserved but it also needs to be protected from pollution.
  2. Saving water is going to save you money and with financial times being tough at the moment every bit saved is going to be helpful.
  3. The amount of drinking water that we have on the earth remains at 1% but the 1% is not constantly found in the same place throughout the world. Water is always on the move.

Saving water is a duty that we all have if we want to continue enjoying access to this life maintaining resource. Domestic water storage tanks can be the best way in which you can start saving water today.