Paleoclimate Scenarios to Inform Decision Making in Water Resource Management: Example from Southern California’s Inland Empire

Abstract

Southwestern United States paleoclimate reconstructions feature droughts that are longer and higher in magnitude than any water shortage during the twentieth century, and thus could aid water managers in planning for future severe droughts. This research used the robust decision-making (RDM) analytical framework to incorporate paleoclimate information into an analysis of long-range water management for a Southern California water agency. The analysis leverages a water management model to identify near-term management actions that may help mitigate water shortages over a wide range of future conditions reflecting various assumptions about climate, costs, and planning. Results indicate that a regional urban water management plan for 2005 is vulnerable to extended droughts and that enhancing water management actions in the near term reduces the risk of future unmet demand and shortage costs. Comparing results with previous work with the IEUA using climate model projections indicates some differences in outcomes related to climate data characteristics such as mean and maximum temperature. This work highlights some problems and potential benefits associated with using paleoclimate data for water management modeling.