New WEAP feature calculates water stress at the local level

When looking at a country’s water stress – a measure of water availability versus demand – it may offer a very general view of how climate change and consumption affect water resources.

But at the national scale, “there’s not much you can really do with that information,” SEI Senior Scientist Brian Joyce said.

“It often doesn’t make a lot of sense to look at water stress at the country level because it hides its relationship to water basins within the country,” he added.

So the Food and Agriculture Organization (FAO) – the UN agency assigned to advance the Sustainable Development Goal (SDG) on water stress – commissioned SEI to develop the functionality within its flagship Water Evaluation And Planning (WEAP) software to calculate water stress on a more local level.

SEI scientists, in collaboration with FAO, built a feature that allows water planners to examine water stress by basin and compare it year to year, providing the level of detail decision-makers need to plan their water resource management.

“What we’re doing is helping countries understand water stress sub-nationally,” said SEI Senior Scientist Annette Huber-Lee, another member of the team that worked on the WEAP feature. “National measurements can miss important vulnerabilities.”

As part of the 2030 Agenda, adopted in 2015, UN Member States are required to report on their progress toward 17 SDGs – and as a user-friendly tool available free to those in developing countries, “WEAP was the tool that was accessible and available for these countries to use,” Huber-Lee said.

“I imagine this tool is something that will be used between now and 2030 more extensively and will help countries with their reporting requirements – and, more importantly, with making informed decisions about resiliently managing water resources to meet both human and ecological needs.” she added. “It’s exciting.”

The FAO definition of water stress is the proportion of freshwater withdrawn to that available for withdrawal for human uses – agricultural, residential and industrial – after taking into account environmental flow requirements. If human users leave only the amount required for ecological flows in natural waterways, that would be characterized as 100% water stress. The greater the water stress, the greater the impediment to sustainable development.

The new function allows users to draw their own boundaries for the area they want to measure. It can show how water stress is changing in different areas of a basin and how it fluctuates over time. Decision-makers can identify hot spots and develop policies to alleviate troubled areas, based on existing baseline data or future scenarios that can be incorporated into the water model.

SEI staff, in collaboration with FAO partners, have trained people in Tunisia, Algeria and Rwanda on how to use the plug-in and have developed a manual in English, French and Spanish so technicians can monitor and forecast water stress on their own.

“As water resources managers, we always need to know the status of water uses and users in order to easily monitor water resources within catchments and sub-catchments,” said one Rwandan trainee. “However, it is quite difficult to find informative, reliable scenarios on water use efficiency and water stress unless using a very advanced model such as WEAP. That is the reason why the calculation of water stress by sub-basin is essential.”

WEAP users may download the water stress plug-in and instructions in English, French and Spanish at this link (see the column on the right).

Join the WEAP forum and download the tool yourself at the WEAP website.