Investigating Barriers to Recovery

Hurricane Harvey made its landfall upon Harris County, Texas in August 2017, and lefts its mark on the Houston area’s environment, economy, and county-wide population of 4.6 million. In its wake, the Category 4 hurricane produced $125 billion in damages, making it tied with Hurricane Katrina for the costliest hurricane in US history. In this article, we outline Harvey’s catastrophic qualities and demographic trends in Harris County and then use these factors to examine building damage patterns and Post-Harvey public health concerns.

An analysis of Harvey must address the impacts of the catastrophic amounts of rainfall that ensued. According to US Geological Survey, Harvey’s eight-day rainfall marked “most significant rainfall event in U.S. history, both in scope and peak rainfall amounts, since records began in the 1880s.” In Harris County specifically, a foot and a half of water covered 70 percent of the 1,800-square-mile county. The weight of this rainfall caused Houston sank two centimeters as a result. The figure below shows areas of Texas that were covered from 20 to 40 inches of rain during the eight-day span:

This map of size of area covered by 20-40 inches of rain demonstrates the scope of Harvey’s impact. According to this map, we see that over 44,000 square miles experienced severe amounts of rainfall in that eight-day period. With an understanding of the geographic scope of Harvey, it is important to delve into the county-level impacts on Harris County.

This map shows population density in Harris County on the Census tract-level overlayed with areas deemed to be in high risk flood zones. Using data from the ACS 5-Year Survey (2013-2017) and flood areas demarcated on Social Explorer, we can gather some interesting insights from this map. First, we can see that a vast majority of Harris County has over 3,000 people per square mile. When comparing this map against the areas that are considered high risk flood zones, we find that although all types of density levels are in high risk zones, there are tracts with very high densities that are particularly affected by high risk flood zones. Evidence can be seen when looking at the western portion of the map in which the high risk flood zones are all in areas at the highest levels of population density.

From this analysis of rainfall and flooding, we find that Harvey not only affected an incredibly large portion of Texas in terms of rainfall land cover, but also disproportionately affected Harris County residents who are living in high risk flood zones. The tracts near most high risk flood zones in Harris County also have the highest levels of population density in the county. This presents insight into how the vast majority of the county’s residents living near high risk flood zones posed an issue for post-recovery efforts. From these maps, we can predict that the sheer number of people affected by Harvey’s rainfall, flooding, and surges was catastrophic and left most households across the county vulnerable to its damaging impacts. Our findings are confirmed by statistics gathered in a report by the Harris County Flood Control District which estimated that over 154,170 homes across Harris County were flooded, constituting about 9 percent to 12 percent of the total buildings in Harris County.

With an understanding of the preliminary damages caused by Harvey from rainfall and flooding on the densely populated areas of Harris County, it is useful to delve into the population characteristics of those who were disproportionately impacted by the hurricane from a spatial analysis on key demographics trends.

This section examines select demographic characteristics of Harris County residents.

Source: 2017 ACS 5-Year Estimates, Table B19013*

This map shows 2017 median household income at the Census tract level for Harris County, Texas. The data are from American Community Survey’s 2013-2017 5 Year Estimates. The map reveals that lower median incomes — indicated by a lighter shade of blue — tend to cluster on the East side of Harris County. Higher median incomes in dark blue are seen on the outer edges of Harris County, particularly on the northwestern edge. The highest median incomes reported in this map are more centrally located and are closer to downtown Houston.

The spatial distribution of median household income provides insight into how tracts in Harris County may recover from Hurricane Harvey’s destruction. Census tracts with lower median household incomes contain more households where recovering to pre-Harvey conditions may be more challenging because of a lack of available funds.

Source: 2017 ACS 5-Year Estimates, Table B25008*

This maps displays the percentage of renter occupied housing units in 2017 for each of Harris County’s census tracts. Like the map above, the data are from American Community Survey 2013-2017 5 Year estimates. Census tracts with higher percentage of renter occupied housing units, colored in dark blue, are more centrally located in the County. Tracts with a smaller percentage of renter occupied housing units, indicated in light blue hues, gravitate to the outer edges of the county. Tracts with a higher proportion of renters compared to homeowners may face more barriers to recovery, and will thus recover more slowly, because most disaster aid funding is directed towards homeowners, not renters. Additionally, renters do not have as much control over the quality of their housing unit as homeowners, which can burden renters with more flood risk.

Taken together, these maps suggest places where households and certain populations face more barriers to a return to pre-Harvey conditions. They reveal how two demographic trends — median household income and percent of renter-occupied housing units — spatially complement each other. Median household incomes at the census tract level are higher in the outer edges of Harris County and these are also tracts that tend to have a lower percentage of renter-occupied housing units. Conversely, tracts with higher proportions of renter-occupied housing units also tend to have lower median incomes. These tracts with a high renter population also tend to be more centrally located within Harris County, unlike tracts with high median household incomes.

*NOTE: The ACS is a rolling survey of a sample of the population. All ACS data are estimates and do not represent true counts of the population. Guidance on how to use and interpret ACS data is here.

With an understanding of the scope of Hurricane Harvey, in terms of rainfall/flooding and geographic size, and the populations most vulnerable to property damage and difficulties recovering, we now analyze the various types of damage that Harvey caused on Harris County. This section will cover physical property damage caused by Harvey.

This map displays the geographic concentrations of property damage as a result of Harvey flooding. This data was collected the Federal Emergency Management Agency on August 27-29th of 2017 and uses building inventories and modeled inundation (i.e. flood) depth to assess potential impacts and provide an estimate of the order of magnitude (i.e. affected building, minor damage, major damage, destroyed building). From this map, we can see that the reported building damages fall mostly along the high risk flood zones that were discussed earlier. Furthermore, there is a cluster of destroyed properties on the southeastern and western edges of the county. This map is layered on top of data displaying the percent renter occupied units on the tract-level in Harris County. This analysis allows us to visualize how major and minor sites of destruction were in tracts that have high percentage of renter-occupied units.

Most of the areas that have clusters of red dots, represented destroyed buildings, are in areas where the majority of residents are renters (with the exception of the southeastern edge of the county). For example, we see a large cluster of red and orange points in the central region of Harris County. Combining this data with our earlier analysis of Harris County’s demographics, we see that many areas with major to destroyed building damage are in areas that are predominantly renter-occupied and low income. Although we see this trend, it is important to note that this is not characteristic of the region as a whole. There are other areas with high levels of damage, such as the southeastern edge of the county, that have very low percentages of renter-occupied units and higher median incomes relative to other tracts in the county. With this in mind, we must still highlight that the key issue in post-Harvey recovery is that the burden of costs are weighed disproportionately upon those who are in the lower median income brackets and live in units that were highly damaged by the storm. Following this analysis of building damage, we believe that it is necessary to extend the category of damage caused by Harvey to other types of impacts, specifically environmental health impacts.

Hurricane Harvey’s impacts extend far beyond building damage. This section visualizes data on damaged toxic sites during the floods to present a public health aspect of the disaster’s impacts

This map shows sites of toxic spills and/or releases from hazardous waste sites, petroleum refiners and transfer terminals, natural gas facilities, wastewater facilities, superfund sites, and power plants as a result of flooding from Hurricane Harvey. This dataset, available here, was compiled by the Sierra Club and aggregates data from the Environmental Protection Agency’s Toxics Release Inventory and the Texas Commission on Environmental Quality.

The sites of toxic releases are mapped over median household incomes at the census tract level for 2017. Layering the locations of Harvey-related toxic releases over median household income allows us to investigate the relationship between these two variables. Sites of toxic releases are well spread out over Harris County. However, there is a concentration of industrial sites on the southeastern edge of the County (near Deer Park, Pasadena, and Baytown), which is where the Houston Ship Channel and the Port of Houston are located. The census tracts around the Houston Ship Channel also have lower median household incomes. Though this spatial analysis is not comprehensive, the concentration of hazardous releases within tracts with lower income households posits even greater challenges to recovery from Harvey as both lack of financial resources and heightened health risks are barriers difficult to overcome.

Though ExxonMobil admitted to releasing hazardous pollutants as a result of hurricane damage, the threat of environmental toxics in the Houston area is not a new problem that Harvey unveiled. Communities living near industrial sites have been organizing to uproot this environmental health injustice for many, many years. Hurricane Harvey, because of the attention it garnered, has simply made this environmental injustice and health inequity easier to see.

In exploring Hurricane Harvey’s impact on Harris County, Texas, we find that damage extended far beyond initial counts of rainfall and flooding. When accounting for changes in demographics spatially in areas where Harvey had the highest impact, measured in both building and public health damage, we uncovered that the costs of Harvey fell disproportionately on those who were in the lower median income range as they were concentrated in areas heavily affected by flooding, building damage, and environmental health hazards and had lower levels of disposable income needed to financially cover these damages. This analysis is important for city planners and federal agencies, such as FEMA, to consider when planning for natural disaster recovery efforts. Moreover, it is becoming critical for cities to be proactive, rather than reactive, in addressing the inequitable cost burden from natural disasters. Looking forward, Harris County must address some of the issues that structurally and systematically affected the county’s ability to respond and recover from Harvey.

Some argue that Houston and Harris County’s lack of city zoning codes worsened the disaster. Others disagree by asserting that impervious land cover, which often accompanies suburban development, prevented floodwater from being absorbed into the soil and increased the destruction the floods caused. In reality, these elements are two of several that explain why Harvey was so catastrophic. Changes in how floodplains are mapped, better building regulations in floodplains, and designing urban green spaces to be floodable are needed to make Houston and Harris County more resilient to natural disasters. Efforts to improve socio-economic equality and health equity, which will dismantle barriers to post-disaster recovery, will only support Houston and Harris County’s attempts to create a more resilient city.