全球智库信息集成服务系统

The decision support tool aided the Delta Stewardship Council in developing a Delta Levees Investment Strategy through four key steps.

• It compiled and displayed information about vulnerable assets throughout the Delta.
• It estimated the probability of flooding and the associated risks to lives, property, water supply, habitat, and other Delta assets.
• It provided interactive visualizations to support deliberations over how to weigh different types of risks to define high-risk islands.
• It assimilated and displayed results of analyses of how different levee investments would reduce risk.

The Delta Levees Investment Strategy analysis seeks to prioritize investments based on how they meet important goals for the state — to reduce flood risks to lives and property, to water supply reliability, and to Delta ecosystem function — and to do so efficiently.

• The foundation for this analysis is estimates of flooding probability due to seismic and hydrologic events for each leveed island and tract in the Delta.
• These flooding calculations are then combined with estimates of different consequences of flooding (e.g., to lives, property, water supply, habitat, and Delta as Place) using a classical "probability x consequence" framing to calculate risk.

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.

• Chapter One

  Introduction

• Chapter Two

  Summary of Risk Evaluation Methodology

• Chapter Three

  Overview and Use of DST

• Chapter Four

  Conclusion