One of the most significant challenges we face today is ensuring an adequate water supply for the world. Researchers from Stockholm University have introduced a new method for assessing the global risk of water shortage. Their findings suggest that the risks to water supply may be greater than previously believed, particularly when considering the environmental conditions and governability of areas where rain is generated.
Typically, when we think about global water supply, we envision rain falling onto the earth, which then collects in lakes, rivers, and aquifers. This perspective is often used to evaluate water security and potential scarcity. However, a recent study published in Nature Water reveals that water risks are influenced by both governance and the environmental conditions in areas where moisture originates before it becomes rain.
“The source of water is actually found in the moisture that evaporates from land and oceans, which later travels through the atmosphere until it precipitates as rain. Often, this moisture from upwind sources is overlooked during assessments of water availability,” explains Fernando Jaramillo, an associate professor in physical geography at Stockholm University and the lead researcher of this study.
When lakes and rivers are shared between different nations or governmental bodies, current assessments and regulations typically focus on upriver conditions, or the areas above the water body. In contrast, an upwind perspective takes into account the regions from which the evaporated moisture arrives before it falls as rain. This area is referred to as a “precipitationshed” and can span vast portions of the earth.
“For example, in tropical South America, while the majority of the Amazon basin lies downriver of the Andes mountains, significant portions of the Andes are actually downwind of the Amazon rainforest and rely on it, demonstrating a mutual dependence for water supply between these areas,” notes Fernando Jaramillo.
The research assessed 379 hydrological basins across the globe and found that the risks to water security increase substantially when considering the origins of the water from upwind areas.
“Our findings indicate that globally, 32,900 km3/year of water needs are at a very high risk, reflecting almost a 50 percent increase compared to the 20,500 km3/year identified through the traditional upstream perspective,” states José Posada, a former doctoral student at Stockholm University and the primary author of the study.
Political influences can have serious implications
Since a significant amount of water is generated through evaporation from vegetation, alterations in land use can impact the availability of water downstream. In areas where deforestation and farming practices are prominent, the amount of moisture contributed by plants may diminish, resulting in reduced rainfall downriver and increasing water security risks.
“For coastal nations like the Philippines, the majority of rain originates from the ocean, meaning that changes in land use carry minimal risks to water security. Conversely, inland countries such as Niger primarily receive rainfall from moisture evaporated in neighboring countries like Nigeria and Ghana. This makes many landlocked nations extremely vulnerable to how water security is influenced by land use changes,” explains Fernando Jaramillo.
Essentially, political dynamics, including environmental management and regulations in the areas where moisture initially evaporates, can greatly impact water safety in regions far away.
“For instance, the Congo River basin is highly dependent on moisture from neighboring countries that frequently rank low in environmental performance and governance as per global metrics, placing it at significant risk from potential deforestation and unregulated changes in land usage nearby,” notes Lan Wang-Erlandsson, a researcher at the Stockholm Resilience Centre at Stockholm University and a co-author of the study.
Effective environmental regulation necessitates an upwind perspective.
The findings of the study highlight why poor governance and environmental conditions in an upwind country can significantly affect the water supply in a downstream nation. It underscores the interdependence between upstream and downstream countries.
“Neglecting the interconnectedness between nations is not an option. Ultimately, all water is linked, and we should not only focus on how we manage resources within our own region or country but also consider the practices of our neighbors,” asserts Lan Wang-Erlandsson.
“We hope that the results of this study will aid in pinpointing where and to whom cooperation efforts can be directed to alleviate the causes of water-related conflicts, which includes addressing atmospheric water movements in international decision-making and governance frameworks. Our findings stress the necessity for global collaboration to manage upwind moisture sources effectively,” concludes Fernando Jaramillo.
