Economic optimization to guide climate water stress adaptation.

Allocation of water over its six dimensions of quantity, quality, timing, location, price, and cost remains an ongoing challenge facing water resource planning worldwide. This challenge is magnified with growing evidence of climate change and related water supply stressors. This stress will challenge food, energy, and water systems as climate adaptation policy measures see continued debate. Despite numerous achievements made many by previous works, few attempts have scanned the literature on economic optimization analysis for water resources planning to discover affordable climate adaptation measures. This paper aims to fill that gap by reviewing the literature on water resource optimization analysis at the basin scale to guide discovery of affordable climate adaptation measures. It does so by posing the question "What principles, practices, and recent developments are available to guide discovery of policy measures to improve water resource system adaptions to growing evidence of climate water stress?" It describes past achievements and identifies improvements needed for optimization analysis to inform policy debates for crafting plans to improve climate resilience. It describes an economic conceptual framework as well as identifying data needs for conducting economic optimization exercises to support river basin planning faced by the challenge of managing the six water dimensions described above. It presents an example from an ongoing issue facing water planners in the Middle East. Conclusions find considerable utility in the use of economic optimization exercises to guide climate water stressadaptation. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Sustaining aquifers economically in the face of hydrologic, institutional, and climate constraints.

Aquifers supply water to millions of farms, thousands of cities, and billions of people worldwide. Water use and economic activity in aquifer-dependent regions cannot be sustained if groundwater levels are not stabilized. This article addresses a question relevant to these regions internationally: how can water scarce areas reduce aquifer depletion while supporting the many economically and institutionally important uses of groundwater, which serve as a critical source of supply in many parts of the world with limited or seasonal precipitation which could become more pronounced in the face of future climate stress. Facing that challenge, this work presents a framework for discovering measures to hydrologically stabilize aquifers that control economic losses while respecting local institutional constraints. It advances our capacity to discover measures to efficiently, equitably, and sustainably allocate burden sharing that protects aquifers while adapting to hydrologic, economic, and institutional characteristics of an affected community. Results of this work show that for the aquifers investigated, present practices of groundwater use are unsustainable and finds that alternative practices are possible. It provides scenarios describing such practices and also determines their hydrological and economic consequences. Finally, it shows how these results can feed into policy debates over the several water-sharing arrangements. This work makes several incremental contributions: calibrating modelled pumping patterns to the historical baseline, controlling economic costs of achieving hydrologic sustainability, respecting institutional constraints governing equitable burden sharing, presenting an approach with powers of generalizability, and using routinely collected data. While the approach and findings are illustrated for two aquifers in Africa, its approach carries some generalizability. All data, variables, equations, constraints, and results are included as appendices.

Managing food-ecosystem synergies to sustain water resource systems.

Measures implemented to restore ecosystem services are widely believed to conflict with food production in the world's irrigated regions because of their competition for scarce water. However, little integrated analysis has been conducted to test this hypothesis. This work tests that hypothesis by presenting results of a basin-scale hydroeconomic analysis linking biophysical, hydrologic, agronomic, ecological, economic, policy, and institutional dimensions of the partially-restored Mesopotamian Marshes of Western Asia. Results serve to partly reject the hypothesis: Here we find that an economically-optimized ecosystem restoration trajectory can be achieved with a minimal loss in food production or farm income where restored wetlands complement important dimensions of food production. Moreover, we find that where water shortage sharing rules can be made more flexible, ecosystem restoration more nearly complements improved food security. Our results point to previously unexplored synergies among food production, ecosystem restoration, and water laws in arid and semi-arid regions internationally.