Decision support tool for the San Francisco Bay-Delta levees investment strategy

The Sacramento–San Joaquin Delta comprises over 100 islands and tracts northeast of the San Francisco Bay. Most are below sea level and are protected by levees, whereas some are tidal or above sea level. The Delta supports a unique ecosystem, communities, and agricultural land, and plays a key role in the California water distribution system. The flood risks facing the Delta are complex and varied. Some islands are at high risk from flood damage to human life or structures and property, whereas others are at risk of impacting the State's water supply, flooding important habitat, or compromising the Delta's historic towns, prime agricultural land, or public roadways. The possible investments to mitigate these risks are numerous, and they will affect Delta risks differently.

The Delta Stewardship Council commissioned the development of a risk modeling framework and decision support tool (DST) to aid in the formulation of a Delta Levees Investment Strategy. This document first reviews the risk analysis methodology used to evaluate the probability of flooding and risks to life, property, water supply, habitat, and Delta as Place under several future time periods and scenarios. It next describes in detail the functions of the interactive visualization function of the DST, including Assessing Risk, Ranking Islands by Risk, and Developing Levee Investment Portfolios.