The balancing act of robust decision-making in complex water resource systems

Balancing drinking water supply and environmental water needs requires careful use of water resources. Some water sources are more resilient to climate extremes than others. For example, groundwater resources can buffer climate extremes, as groundwater storage in aquifers is slowly released, complementing water supply from surface sources during periods of water scarcity, heatwaves and (extreme) drought events. However, this resilience declines when groundwater storage is compromised due to periodic or sustained overuse with severe consequences for groundwater-dependant ecosystems. Sustainable groundwater management needs a robust decision-making approach, that looks beyond historical drought events and prepare for a possible combination of extreme conditions in a future climate, including not only climate uncertainty but also a changing water anthropogenic demand and environmental water needs.  

In this study we present a bottom-up approach to support robust decision-making to improve climate resilience of drinking water supply systems, considering both surface water and groundwater use. We consider uncertainties related to model parameters, changing water demand and future climate conditions, as we apply this method to a system-level representation of a water management region in South England.  

Results show under which climate conditions current water management strategies are confidently meeting drinking water supply with a margin for (seasonally) increased water demand. Future extreme conditions reveal increasing competing interests with environmental water needs and possible shortages in drinking water supply. Mapping the associated (un)certainty of short-term and long-term management strategies shows the value of robust decision-making to sustainable water use in complex water resource systems.