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What’s the Dam Problem? Hazardous Dams, Flood Risk, and Dimensions of Vulnerability in California

  • Author(s): McOmber, Britta
  • Advisor(s): Hecht, Susanna
  • et al.
Abstract

In the state of California, dams are aging, underfinanced, and in many cases ill-maintained. The Oroville Dam Spillway Failure in February 2017 demonstrates that even dams with satisfactory condition ratings can be at risk of failing from a combination of climatic, political, economic, and structural factors. It is therefore necessary to look beyond the condition assessment of a dam and instead consider the hazard potential status. California has 833 High Hazard Potential (HHP) dams – which the U.S. Army Corps of Engineers defines as dams that would cause significant loss of life, property destruction, or environmental damage in the case of failure or misoperation (2016).

Expanding on previous literature on the sociodemographic determinants of flood-risk in cases of sea-level rise, climate change, high precipitation, and storm events, this project analyzes variables of social vulnerability within HHP dam inundation boundaries. I rely on a series of geostatistical analyses, two-tail independent samples statistical tests, and multiple linear regressions to answer the overarching research question – Who is most vulnerable to dam-induced floods in California?

The data underpinning this research comes from the National Inventory of Dams, statewide dam inundation boundary maps, and the 2012 -2016 American Community Survey. Results from independent samples t-tests show that individuals and households are disproportionately located within hazardous dam flood zones if they are U.S. Citizens, live with a disability, are less educated, are unemployed, are single parents, have lower median household incomes, live at, below, or near the federal poverty line, and identify as either Black and African American, American Indian and Native Alaskan, or Native Hawaiian and Pacific Islander.

Furthermore, people whose highest educational attainment is a high school degree, unemployed individuals, those living with disabilities, Hispanic or Latino individuals, female-headed households, renters, and people who identify as Black and African American, American Indian and Native Alaskan, Asian, and Native Hawaiian and Pacific Islander represent variables of social vulnerability that are statistically significant predictors of living within a hazardous dam flood zone. This project therefore reveals the spatial and social characteristics of vulnerability to dam-induced flood risk in California.

Planners and policymakers can use this information to improve existing disaster management and response plans by incorporating targeted and specific strategies to reduce the flood-risk of highly vulnerable populations. My findings also provide information necessary for planners and policymakers to address and mitigate the existing social and spatial inequalities in dam inundation zones to create a more environmentally just California.

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