Spatial planning for water sustainability projects under climate uncertainty: balancing human and environmental water needs

Abstract

Societies worldwide make large investments in the sustainability of integrated human-freshwater systems, but uncertainty about water supplies under climate change poses a major challenge. Investments in infrastructure, water regulation, or payments for ecosystem services may boost water availability, but may also yield poor returns on investment if directed to locations where water supply unexpectedly fluctuates due to shifting climate. How should investments in water sustainability be allocated across space and among different types of projects? Given the high costs of investments in water sustainability, decision-makers are typically risk-intolerant, and considerable uncertainty about future climate conditions can lead to decision paralysis. Here, we use mathematical optimization models to find Pareto-optimal satisfaction of human and environmental water needs across a large drought-prone river basin for a range of downscaled climate projections. We show how water scarcity and future uncertainty vary independently by location, and that joint consideration of both factors can provide guidance on how to allocate water sustainability investments. Locations with high water scarcity and low uncertainty are good candidates for high-cost, high-reward investments; locations with high scarcity but also high uncertainty may benefit most from low regret investments that minimize the potential for stranded assets if water supply increases. Given uncertainty in climate projections in many regions worldwide, our analysis illustrates how explicit consideration of uncertainty may help to identify the most effective strategies for investments in the long-term sustainability of integrated human-freshwater systems.

Future Projection of Precipitation Changes in the Júcar and Segura River Basins (Iberian Peninsula) by CMIP5 GCMs Local Downscaling

“…Given the local spatial resolution of the results, their use in small-scale (municipal and local) hydrological planning is very interesting as this is one of the challenges faced today in climate modeling [24]. Indeed, spatial planning requires high spatial resolution climate models that can be included in proposals about assigning new land uses and urban designs.…”

Small increases in stream drying can dramatically reduce ecosystem connectivity

“…Water management strategies that aim to incentivize reductions in water usage (Zamani Sabzi, Rezapour, et al, 2019) or set targets for environmental flows (Sandoval‐Solis et al, 2022; Wineland, Bașağaoğlu, et al, 2021) should carefully consider the potential for nonlinear impacts of stream drying. In our study, stream drying is associated solely with climatic changes, and water managers should seek to identify water sustainability strategies that are robust to future climate uncertainty (Farzaneh et al, 2021; Fovargue et al, 2021; Wineland, Fovargue, et al, 2021). Independent of climate, humans can exacerbate drying further via consumptive water use and land use change (Bond et al, 2008; Jung & Kim, 2017), raising the potential for hotspots of declining water availability due to groundwater pumping (Perkin et al, 2017) or other societal uses (Guo et al, 2019; Zamani Sabzi, Moreno, et al, 2019).…”

The environmental flows implementation challenge: Insights and recommendations across water‐limited systems

“…Despite these challenges though, it can be feasible to implement e-flows at a subset of locations across the basin under future climate uncertainty if biodiversity conservation is a priority objective (Wineland, Fovargue, Gill, et al, 2021). Additionally, by jointly considering how water scarcity and future climate uncertainty vary independently by location, sites can be prioritized for strategic water investments to boost water availability (Fovargue et al, 2021). By incorporating climate uncertainty into e-flows planning and conservation prioritization frameworks, feasible targets can be identified as a preamble to broader-scale e-flows adoption approaches.…”