Developing an investment strategy for resilient water systems

Preparing for different futures 

Our team worked with the Ethiopian Ministry of Water and Energy to create a roadmap for improving water resilience, applying a decision-making under deep uncertainty (DMDU) approach.

DMDU acknowledges that the future is highly uncertain. The number of variables and the range of outcomes for each variable make attempts to predict and plan for specific conditions unwieldy and unworkable. Instead of attempting to forecast the future accurately and recommending a single course of action, we used DMDU to identify a whole range of different possible futures, and tested potential infrastructure, policy and management measures against each of those futures. On this project we applied a DMDU approach to just the UAUK basin, but it can also be used to shape a national or transnational strategy.

Using specialist hydrological modelling software and computing power developed within just the last few years, our team could explore hundreds of thousands of plausible scenarios and the impact of different sequences of interventions in each. Sample interventions included building dams, fixing leaks in the supply network and a variety of demand management strategies.

Drawing on our experience with the City Water Resilience Approach, we worked with stakeholders in UAUK to build local development plans, priorities, performance metrics and potential policy levers into the model. We held regular workshops with stakeholders including the Ministry of Water and Sanitation, The World Bank, Addis Ababa Water and Sanitation Agency and academics from Addis Ababa University.

These workshops helped us incorporate vital local knowledge and to take account of the local political, economic and geographical context in our recommendations. This ensures that investment in infrastructure will always be targeted where it’s most needed, whether that investment takes place in five, ten or twenty years’ time. 

We also built capacity among key departments and academics in Ethiopia. Sharing our experience, open-source tools and processes means that local teams can use, review and adapt the pathway as needed. Arup’s experts have offered ongoing support to help maintain the model and support new users. 

Managing demand for water 

Our analysis revealed that high and rising demand for water is the most likely driver of a potential system failure, so strategies to manage demand are crucial. If this continues to be the most significant factor, our pathway will recommend options such as increased metering ratios, reducing non-revenue water and regulating abstraction. The pathway will also point to measures that address the root causes of high demand such as changing planning regulations to shift demand to locations with a more abundant water supply.

Grouping options into adaptive pathways suited to the different plausible futures gives a flexible roadmap to a more sustainable future. The short, medium, and long-term strategies provide a clear picture of the options for investment. This can be used by Ethiopia’s Ministry of Water and Energy, and by external organisations such as the World Bank.

If conditions such as economic activity change – or if better information becomes available, then the model can be re-calibrated. This will generate new recommendations to ensure that investment will help the water system to remain as resilient and robust as possible, whatever the future holds.

It could take ten or even twenty years to construct a new dam in the UAUK sub-basin. But the tools and processes we have developed are already supporting local decision-makers. They can now be confident they are taking evidence-based action that will help to safeguard the water supply for millions of people.