Robust Water Resource Decision-Making Under Internal and External Uncertainties: A Study of Latin America

Considering water resource scarcity and uncertainty in climate and demand futures, decision-makers require techniques for sustainability analysis in resource management. Through unclear definitions of “sustainability”, incomplete decision-making tools, and short-term planning, however, traditional approaches to resource management propose options of limited robustness to planning uncertainties. This work first proposes a robust, multivariate, dynamic sustainability evaluation technique called Measure of Sustainability (MoS) that is more adapted to withstand future parameter variation. The range of potential future climate and demand scenarios is simulated through a calibrated hydrological model of Copiapó, Chile, an example of an arid watershed under extreme natural and anthropogenic water stresses. Comparing MoS and cost rankings of proposed water management schemes, this work determines that the traditional evaluation method not only underestimates future water deficits, but also espouses solutions without considering supply and demand uncertainties.

Secondly, this research addresses internal and external uncertainties in the Water Reuse and Recycling (WRR) technological decision-making process through the utilization of Fuzzy TOPSIS. Applied to four Latin American study sites, this technique is compared with the weighted sum method to demonstrate its improved robustness to variability in the number of evaluation criteria and stakeholders surveyed. Additionally, this research determines that stakeholder valuations of WRR technology selection criteria align less with other stakeholders from the same watershed than with those of the same water use sector in drastically different watersheds.

Finally, the third objective of this research is to demonstrate with long-term Cost-Benefit Analysis that under conditions of climate change and market expansion, the benefits of replacing groundwater extraction with alternative water sources outweigh the costs of lowered water tables and farm failure. Through integrated hydrologic simulation, this economic approach is applied to the Copiapó River basin in Chile, where the long-established agricultural sector is being forced by market forces to fallow crops and sell crucial water rights. Results from our application of Cost-Benefit Analysis to a robust outlook of future climactic and demand scenarios determine that substituting groundwater extraction with desalination for irrigation requirements could provide a potentially economically viable option for future water scarcity alleviation.