What has become known as the water storage gap is an undeniable crisis in the water industry that will continue to grow unless action is taken now. There is growing concern that natural water storage is declining, the amount of built storage has declined, and what is available is ageing and waning.

Over the past 50 years, more than 27,000 billion m3 of water storage has been lost due to melting glaciers and snowpack and the destruction of wetlands and floodplains. In addition the volume stored in large dams has come under threat as sediment fills space in reservoirs and the structures are ageing faster than the pace of rehabilitation and new construction. As freshwater storage declines global populations are increasing, and with the shadow of a warming climate looming in the background where over 1.65 billion people have been adversely affected by floods (an increase of over 24% compared with previous decades), it is becoming clear that worldwide water insecurity can only be resolved through a changed approach to planning and managing water storages.

In its new overview for policymakers called What the Future Has In Store: A New Paradigm For Water Storage, the World Bank calls for “developing multi-sectoral solutions to the water storage gap, taking approaches that integrate the needs and opportunities across the whole system, including built and natural storage”. It adds that the framework will help to accelerate collaboration between economic sectors and public and private stakeholders globally, overcoming the storage gap to help supply the water and water security needed by communities worldwide.

Close the gap

Closing the global water storage gap is a shared challenge, the bank says. Global, national, and regional stakeholders can no longer focus only on their own needs in isolation. A conceptual shift in thinking, anchored in an integrated, systemic approach to planning and managing water storage, against the backdrop of broader integrated water resource management, is imperative if sustainable, climate-resilient water storage solutions that sustain generations are to be achieved.

In 2018, as the World Bank highlights in its report, South Africa’s Cape Town “was in striking distance of catastrophe” and made international headlines as its taps ran dry and four million people in this modern metropolis were on the verge of “one of the largest drought-induced municipal water failures in recent history”. The experiences of Cape Town, which also endured intense flooding that almost stretched the city’s stormwater infrastructure beyond capacity in 2022, is a graphic illustration of what is now an international crisis.

Indeed water storage is being viewed as an important vital tool for adapting to climate change, providing a mechanism to offset some of the hydrological changes brought about by climate change by improving water availability and reducing the impact of floods. Built water storage gives water managers more control over resources while also providing an important contribution to climate change mitigation through the production of hydropower and its enabling role for other renewable energy.

Suleiman Hussein Adamu, the Minister of Water Resources in Nigeria believes, agrees that freshwater storage is at the heart of adapting to climate change.

“I`m very glad to see that there`s a strong shift now from too much discussion on emissions, to discussions about how climate change relates to water,” he said at the launch of the World Bank report in February 2023. “I think one of the areas where we see the quickest impact of climate change is in our water resources, and I`m glad that this is taking a prominent position.”

Suleiman Hussein Adamu explains that the droughts of the 1970s in Nigeria highlighted the fact that “water storage was going to be of great importance” to the country. As many of its rivers are silted up and seasonal, a form of storage was required. Since then, a lot of investment has been made into building dams and reservoirs, especially as a large part of the population`s agricultural area is in the Sahara region where rainfall is erratic. Although the country is still dealing with excess sedimentation leading to reduced storage in rivers and reservoirs, the hydropower benefits of dam storage has been of great value. Adamu also spoke about issues such as capacity building to maintain existing infrastructure, coordinated reservoir operations and balancing the demand between water supply, irrigation and flooding,

“In a lot of cases,” Nigeria’s Minister of Water Resources says, “we found some years where we had excess rainfall and because of the storage capacity of the reservoirs has reduced, we found ourselves opening more gates and valves over time, and downstream communities are seriously affected when that happens. Even when there`s no natural flood, some of our reservoirs tend to create this kind of flooding situation downstream.”

Therefore in Nigeria, the previous experiences of downstream communities before river basin management was given greater consideration, have led to “politically explosive” challenges when it comes to modern-day requirements of building new reservoirs where they are needed.

“Some downstream committees tend to feel short-changed, and it`s been difficult sometimes to construct new reservoirs that we feel are really, really needed. It`s becoming quite explosive, politically explosive,” Suleiman Hussein Adamu commented. “But I think by and large, storing water has been of major benefit to us as we have quite a number of large-scale irrigation systems which would not have been possible without some of the storage that we`d invested on years before.”

As the World Bank acknowledges, closing the water storage gap will require policy and decision-makers to bring together a range of both public and private economic sectors and stakeholders, to develop and drive multi-sectoral solutions that address the water storage gap holistically, effectively, and efficiently.

“Done right,” the bank says, “a new paradigm for water storage will create a stronger foundation for sustainable development and climate action and resilience, paying dividends for populations, economies, and the planet, through years and generations to come.”

Inherently challenging

Planning, building and managing water storage is “inherently challenging” and perpetuates the storage gap, the World Bank report admits. That’s why it has created the 5Rs for increasing storage which have been adopted from the Uncommon Dialogue on Hydropower, River Restoration, and Public Safety that was developed by the Stanford Woods Institute for the Environment in 2020.

The 5RS: Opportunities for Increasing Storage Services are:

  1. Re-operation – The modification of storage operations for improved management (efficiency gains), which might include changing the timing of water releases from controllable infrastructure to increased benefits, or adding additional benefit streams, such as flood control or minimising storage losses from evaporation, etc. This may also include managing for synergies between different types of storage or creating new connections between existing storage so that they can be operated as part of a broader system.
  2. Rehabilitation – The rehabilitation of natural or built storage to improve storage capacity or performance. This can mean ecosystem and natural landscape restoration to its more natural state or extending the life of existing built storage capacity or restoring original or slightly improved capacity through addressing structural defects, sediment removal, increasing the flow rates of managed aquifer recharge sites, and environmental restoration of natural storage sites, among others.
  3. Retrofitting – The upgrading or augmentation of capacity at existing storage facilities, and/or enabling new uses of the facilities. This could be achieved through raising the height of a dam or adding new hydro-mechanical or electro-mechanical equipment to serve different objectives or different customers to make overall gains in the value of storage services. Examples include adding floating solar panels to existing hydroelectric projects, or adding hydropower generation to irrigation projects.
  4. Reform: Investing in institutions to manage storage better – In addition to physical investments in storage, policymakers need to invest in institutions that are required to better plan and manage storage. This includes institutional capacities to manage the data, modelling, and planning systems required to develop smarter storage; enable and incentivise integrated planning, development, and management at multiple scales across multiple stakeholders; mobilising finance and financial incentives that enable storage to be prioritised, planned, and managed in the broader public interest.
  5. Raising New: Finding or developing additional storage – This involves exploring the full range of available storage types: natural and built; surface and subsurface; large and small; centralised and distributed.

“Given the growing risks of water insecurity around the world, particularly in the face of the climate crisis, our approach to planning and managing water storage must change,” the World Bank urges, adding that policy and decision-makers have a unique opportunity to lead.

Government finance and planning ministries are being encouraged to ensure that natural and built storage are effectively and efficiently serving the needs of the greatest number of stakeholders. If mechanisms for joint planning are not already in place, ministries can host or facilitate joint planning processes, or be a neutral arbiter if the political economy around storage requires one. In addition, local governments, storage operators, and water users are urged to champion the new paradigm by engaging in aggregated, integrated planning processes for current and future storage service needs, and evaluating the performance of current storage systems and options for improving them. “This,” the bank cautions, “is no small task.”

In addition, the bank says that lawmakers:


  • Can mandate or incentivise joint planning for storage and broader water use if such mechanisms do not already exist in the form of basin authorities or other joint planning bodies.
  • Allocate budget for a range of storage options across the 5 Rs, helping overcome bias toward investing in new and built-over improving current and green storage solutions.
  • Institute appropriate legal measures for safety, maintenance, and operation to help ensure storage can deliver benefits long term.


While transboundary river basin organisations and their stakeholders are being encouraged to engage in or even lead joint planning processes to identify the shared benefits of cooperative, transboundary integrated water storage management and development, seek ways to engage jointly in risk reduction and work to develop benefits and risk-sharing frameworks between riparian states.

Finally, the banks says that development partners and financiers can convene and support multi-sectoral storage planning processes, invest in activities around the 5Rs that have had proper due diligence, and support countries to engage in transboundary planning processes around storage.

The actions required to implement the new paradigm for water storage are multifaceted and challenging, the World Bank concludes. But, it adds, investing in storage as a system is an investment in economic resilience, social welfare, and the environment.

This article first appeared in International Water Power magazine.