This paper is the third in a series of research papers published by the Baker Institute about Hurricane Harvey and Houston’s response to it. The previous two were: Houston a Year After Harvey: Where We Are and Where We Need to Be, and Houston Flooding: 3.5 Years After Harvey.
On Aug. 25, 2017, Hurricane Harvey came ashore at Port Aransas, Texas, as a Category 4 storm and then stalled. Rather than moving inland, Harvey became a tropical storm as its windspeed decreased and it slowly meandered northward along the Texas coast for several days, dumping an enormous amount of rain from Victoria to the Louisiana border. Unlike other tropical storms that have hit the Houston area before, all areas of the Houston region suffered significant flooding.
In the aftermath of Harvey, substantial attention was focused on flooding. And make no mistake about it — the city of Houston and Harris County have taken a lot of action, as have many other governmental entities. For example:
- Floodplain Regulations Changed. The city of Houston and Harris County changed their floodplain regulations to make them more protective and restrictive, choosing to use the 500-year flood level rather than the obsolete 100-year flood level on the current mapping as the regulatory standard for setting the height of house slabs. This may change under the new floodplain maps to be released in late 2023 or early 2024.
- Bond Money to Address Flooding. Harris County passed a $2.5 billion bond issue to address flooding, and well over 100 projects have been either completed or are under construction across all 22 watersheds using this bond money.
- Updating Floodplain Maps. Harris County, in association with the Federal Emergency Management Agency (FEMA), is redrafting the floodplain maps for Harris County using updated rainfall data provided by the National Oceanic and Atmospheric Association (NOAA) Atlas 14, which increases the 100-year, 24-hour rainfall by about 30% to 35% for Harris County (it varies by location but generally goes from about 13 inches to 17 inches).
- Congressional Funding: Corps of Engineers. Congress and the Texas General Land Office (GLO) acted to provide funding to the U.S. Army Corps of Engineers for four major flood reduction projects (on White Oak, Brays, and Hunting Bayous, and Clear Creek), and work on these projects is ongoing.
- Federal Funding: HUD. The GLO also allocated funds to the city of Houston and Harris County through the federal Department of Housing and Urban Development (HUD) for flood relief.
- Community Development Block Grant Disaster Recovery Funds. On June 6, 2023, the Harris County Commissioner’s Court approved HCFCD’s list of projects for $322 million in Community Development Block Grant Disaster Recovery (CDBG-DR) funds as well as $502.5 million in mitigation funds. The $322 million is unspent disaster relief funding reallocated by the GLO, while the $502.5 million is a part of HUD’s second batch of awards and to be used for 2018 Flood Control Bond Projects. HCFCD has been authorized to take all necessary actions to expedite the administration of the funding.
- Texas Flood Planning. The state of Texas created a major flood planning effort in the Texas Water Development Board.
- Culvert Maintenance. Mayor Sylvester Turner announced that the city of Houston would take back from local residents the responsibility for maintaining open ditch culvert crossings within the Houston — addressing a major concern with this flooding infrastructure.
- New Flood Control Director. Harris County hired a new director of the Harris County Flood Control District (HCFCD), Tina Petersen, who comes from outside of the district. Her experience and approach make her well suited to help Harris County identify and adopt the updated and new policies that are needed.
While these are all excellent steps forward, they are only the beginning. In this paper, we first outline what still needs to be done to address our flooding issues and then conclude by proposing a number of specific action points.
We Are Exposed
From the outset, one thing is clear — flooding poses a very large risk to the economic future of Houston and Harris County. This is not a terminal condition — it can be addressed. But to address it adequately, we will need to make many changes, most of which will be hard.
Addressing Different Types of Flooding
Three types of flooding are of concern to Harris County:
- Local rainfall (pluvial) flooding.
- Riverine (fluvial) flooding.
- Hurricane surge flooding.
We have experienced local rainfall and riverine flooding time and again, so we are most familiar with these two types of flooding.
Surge Flooding is Violent. Surge flooding, however, is very different. Hurricane surge flooding is violent, whereas rainfall or riverine flooding is more passive. And we don’t talk about these differences nearly enough.
We repeat, surge flooding is violent. It is driven by hurricane-force winds pushing ocean water inland. Waves form on top of this rising water, and together they can batter coastal foundations, storage tanks, and chemical process units. Debris from one destroyed building becomes a battering ram on the next building. Containers float and become missiles hurled by the crashing waves, penetrating storage tanks and bedrooms alike.
Surge Flooding Is Rare, but the Risk Is Rising. Hurricane surge flooding is relatively rare compared to the much more common 20-inch rains experienced with major tropical storms like Allison, Harvey, and Imelda. However, data indicates that while climate change may not increase the number of storms, it will increase the intensity of the storms that form. More Category 3, 4, and 5 hurricanes are coming.
Surge flooding is a very real, very current problem for which we are poorly prepared. The surge anticipated from a reasonably foreseeable strong Category 3/weak Category 4 hurricane is shown in Figure 1 — see the inset area over a map of the current 500-year floodplain.
Figure 1 — Coastal Surge Flooding Modeling
Two Recurring Themes
As we explain the flooding issues and outline action points, two themes will come up again and again in this paper.
Surge Flooding is a Real Risk NOW. While solutions are coming, they will not be constructed and operational for at least a decade, or more. They are future solutions, but surge flooding is a real risk NOW.
Increasing Rainfall and Flooding Mean Much Work Is Ahead. In addition, we will experience more extremely strong rainfall and hurricane events in the future. The flood reduction and mitigation projects under construction today were designed based on rainfall and flooding data that are now obsolete. Although the improvements that are underway will still be helpful, they were designed to contain storms that we then considered large. The reality is they will not be adequate to handle the types of storms that we now know to expect.
The bottom line is that we have much work ahead of us.
Addressing Climate Change
Beyond the Bell Curve. We can no longer assert that extremely large storms are aberrant or “off the charts,” as Harris County Flood Control District proclaimed in the heading of its 2002 report about Tropical Storm Allison. Let’s consider the bell curve of standard distribution that provides a common statistical basis for engineering and planning decision-making. The assumption behind the use of the bell curve in hydrology for engineering purposes is that data from the past is randomly distributed and provides a guide for what is expected to happen in the future. This has led to the adoption of the historic 100-year (1%) rainfall event, based on statistics dating far back into the past. However, as can be seen from Figure 2, recent storms in Houston have clustered beyond the 1% (100-year) line — see the purple line in Figure 2. The storms to the right of the 100-year purple line are at the far edge of the bell curve of normal distribution of rainfall over the past century.
Figure 2 — Bell Curve Illustration Showing Recent Major Storms
Although these storms have been referred to in the past as 1,000-year storms, our climate-changed reality today is different: Large rainfall events are becoming much more normal and our analytics must change to reflect this.
For too many years we debated whether climate change was happening. We now accept it but face great challenges in countering this local and global threat. We have wasted enough time.
Increased Storm Frequency and Intensity. It is important to understand how pervasive this change in storm frequency is. We are seeing an increase in intensity of rainfall over every time period measurement — ranging from hours (one, two, six, 12, and 24) to up to two and four days. Our engineers historically have relied on statistics from the past to help them design for the future, but that method does not work when storm intensity is increasing yearly and the sea level is rising.
New Approaches Needed to Face the New Challenges. To effectively address these challenges city, county, state, and federal officials need a focused and informed approach. Our basic building concepts must change. Our concept of flooding and floodplains must change. The 100-year and 500-year rainfall and flood levels (see New Floodplain Maps discussion below) have already changed and will continue to do so. Old historic records are no longer dependable indicators of the future, so we must develop tools to help us make informed decisions in light of these changes — tools that can tease out the climatic changes and provide dependable metrics for decision-making.
Perhaps the most frightening aspect of this unfolding challenge is that the predictive tools we need either do not exist or are not widely accepted and used. This lack of effective analytical tools is hindering the ability of our institutions and professions to respond to climate change.
Consensus is Needed to Face These Challenges. Houston ought to be at the forefront of responses to these challenges simply because we have been hit many times with very large storms. There should be an emerging consensus about what to do, but such a consensus has been slow to evolve. We have only just begun to appreciate and address this climate-changed weather pattern and the difficulties in conducting the serious conversations needed to find solutions. Even today these issues are not easily discussed in certain circles or with certain elected officials.
Make no mistake about it — this is a human evolutionary challenge. Are we capable of comprehending these changes and adapting our engineering standards, our roadbuilding criteria, and our home construction practices to address these challenges?
This is both the most important and most difficult aspect of facing the reality of climate change.
Living With Water
The concept of “living with water” originates from the Dutch: With a revolutionary program called “Room for the River” they bought out development and expanded the areas dedicated to rivers, providing more room for flood water. Living with water is a necessity for Houston and Harris County, but as an urban planning concept, it is unclear. Nevertheless, since Hurricane Harvey, discussion of the issue has gained considerable traction: See, for example, an op-ed in the Houston Chronicle and a report for the city titled Living with Water.
Today in Houston, urban planners, flood control officials, and engineering firms all use the phrase “living with water” in conversation to describe the reality that is 21st century Houston. However, few can articulate what living with water means for Houston, whether in terms of urban planning, flood control, or more generally for the life of the city. So — what does it mean? We will focus on two broad concepts that encompass the major issues:
- Acknowledging the real risk of flooding.
- Flood-prone development.
Acknowledging the Real Risk of Flooding
Flood Markers and Signs. Acknowledging the real risk of flooding is perhaps the most important part of living with water. A favorite anecdote about Houston’s approach to flood risk arose after Hurricane Ike (2008) when a flood marker was placed in the Clear Lake area near Galveston Bay showing how high the storm surge would be at a central intersection for Category 4 and 5 storms (see Figure 3). That flood marker was removed after two months because, we were told, “it interfered with home sales.”
Figure 3 — Flood Marker in Clear Lake Area Showing Surge Levels
Now, think about that for a minute. This marker was not removed because it was wrong — in fact it was right on target. Instead, it was removed because we as a community were more concerned about selling houses than telling our citizens the truth about the real risk of hurricane surge flooding. A similar experience transpired in the city of Houston on Brays Bayou with the removal of signs about past rainfall-generated flooding.
That is not “living with water.” It is denial of risk. This attitude is dangerous and supports uninformed decision-making. It is completely opposite to the mindset needed for living with water.
Warning Residents of Forecast Floods. A different problem came up during the Harvey flooding event. Massive flooding occurred behind and downstream of Addicks and Barker Dams in West Houston in late August 2017 and lasted for days. The Army Corps of Engineers, which is responsible for operating these two dams, had forecast major flooding behind the dams as early as August 24. Although these forecasts were relayed to at least some local officials, neither the residents behind the dams nor those below the dams received any flood warning before they woke up and stepped into flood waters in their homes on Monday, August 28. That is simply the wrong way to go about living with water.
Off-the-record discussions have revealed that local officials chose not to release these flood projections to the public because of concern that this information would cause panic among the residents. This concern emphasizes that we must accustom our residents to honest discussion about real flood risks and the need to evacuate certain high-risk areas. If we cannot have an honest conversation about the real risks and if our people are not used to hearing and thinking about their flood risk, it is unreasonable to expect that they will respond without panicking when the reality of a major flood event looms.
Flood Warning Systems. Along this line of thinking is the issue of flood warning systems. If one knows where to look on the Harris County Flood Control District website for its extensive stream-gaging network, information can be found about the current (and historic) water levels in the creeks, bayous, and rivers of Harris County, but there is no information about projected future levels immediately prior to or during a storm event. However, two local flood warning systems do exist in the Houston area:
- A system that projects future flood levels on Brays Bayou was constructed for the Texas Medical Center by Philip Bedient at Rice University and has been extremely successful.
- Another flood warning system was developed by Bedient and funded by the city of Houston for White Oak, Sims, Hunting, and Brays Bayous, but an effective communication outreach for this system simply does not exist yet.
Right now we lack a comprehensive, effective flood warning system for our flood-prone community. An effective flood warning system would include education, outreach, multiple measures of communication, and predictive modeling at the time of the storm with results continuously transmitted to the public. We need the public to know what to do in such an event. That should be a priority.
Above all, we need to talk honestly — and communicate effectively — about our real flood risk and how to live with water. Specifically, we need to:
- Inform our residents of past flood levels by placing markers throughout the community.
- Develop a flood warning system with public transmission.
- Have an evacuation plan for those living in flood-prone areas.
- Ensure that buy-out money is available when a flood occurs, not three years later after repairs have been made.
Living with water means that we must make room for conveying stormwater. Legacy development in Harris County and Houston dates back to an era before floodplain regulation, and substantial legacy development is adjacent to the 22 creeks, bayous, and river systems that cross Harris County. Today, over 150,000 homes and commercial properties are located within the 100-year floodplain. However, 200,000 homes and apartment buildings flooded during Harvey, indicating the flood risk is much greater than shown on the current federally approved floodplain maps — indeed, they are acknowledged to be obsolete and are in the process of being redrafted based on an increased rainfall amount (see New Floodplain Maps section below). These new maps will include local urban (pluvial) flooding, which is not used by FEMA, but will be provided to the community to communicate risk.
We Need to Make Room for Water. The creeks and bayous of Harris County and the city of Houston need more capacity for flowing water. Because stormwater simply follows gravity no matter what stands in its way, the pathways that the water follows on its way from the city streets and county roads to the major drains must be identified and accommodated. The term “flood control” itself is in a sense outdated — the old methods sought to control the flow of floodwater, but there is realistically no way to control a storm as large as Harvey, Imelda, or Allison. When living with water, planning and engineering involves understanding where gravity will take floodwater and clearing the way for it.
Buyouts to Remove Flood-Prone Houses. To clear the pathways, we will need to remove thousands of homes from flood-prone areas over time. In the past, little if any public money was available to buy out flooded homeowners immediately after a flood. Most flooded homeowners were left with bad choices — leaving their mortgage and equity behind or borrowing money to make repairs to protect their largest personal investment. For most, making repairs was the only sensible response, and this was readily accepted by our government and lenders. Homeowners often don’t see buyout money until 12-24 months after they volunteer for a program. When buyout money finally became available, most landowners declined these offers because they felt — at least for the time being — secure in a newly repaired home.
Residents Want To Stay In Their Neighborhoods. Another concern about buyouts is that most residents generally like their neighborhoods and wish to remain there. In northeast Houston, historic African American neighborhoods offer the comfort of church and community. In the southwest, the Jewish community is centered around Brays Bayou and their religious and cultural institutions. Residents become comfortable with the roads, stores, schools, and amenities of specific sub-areas of this large metropolitan area. Without replacement housing relatively near the location of the flooded home, an offer of buy-out may be declined. This situation is exacerbated in lower-income areas with few available affordable units. There is a clear need to combine housing and flood planning, but implementation of that concept is only just beginning.
Ultimately, we will need to dedicate more land area to water holding and especially conveyance. We typically have not thought this way. The idea of making room for water conveyance is alien. That will need to change.
New Floodplain Maps
Revealing real floodplains has always been a contentious issue in Harris County. Floodplain mapping and regulation was forced on Harris County by the federal government with the passage of the Flood Disaster Protection Act of 1973. Since then, floodplain regulation has often been viewed and discussed as red tape forced upon the local community by the “feds.”
Politics and Development on the Floodplain. In the early 1980s, Harris County became the first county in the United States to gain permission from FEMA to undertake its own floodplain mapping analyses. The maps became political footballs during the 1980s during a period when considerable amounts of development were occurring in the suburban areas surrounding Houston. Parts of the legacy floodplain were developed, including many areas that are now experiencing significant flood problems.
Public discussions about floodplains seldom emphasized the danger of floodplains or that they should be avoided or evacuated. Instead, the message was just the opposite — that floodplains could be developed and that Houston needed floodplain development. In fact, in April 2018, six months after Harvey and after passing more stringent floodplain regulations, Houston Mayor Sylvester Turner led the City Council to vote on allowing the formation of a municipal utility district to develop floodplain lands in west Houston, saying that this shows that more stringent requirements don’t interfere with developers wishing to build in Houston.
Notwithstanding this sentiment, Houston and Harris County did establish more stringent floodplain regulations after Harvey. In fact, both the county and the city adopted new floodplain regulations that established the 500-year floodplain as the standard, including a requirement to build 2 feet above that level. This regulatory change was based on a general agreement that our old 100-year rainfall level of about 13 inches in 24 hours was obsolete and that the 500-year rainfall used in making the most recent official maps was much closer to the current 100-year rainfall — about 17 inches, based on NOAA’s recently published Atlas 14 rainfall data. Currently, the floodplain maps for Harris County are being redone and updated based on this updated NOAA Atlas 14 analysis. These new maps are supposed to be forthcoming in late 2023 or early 2024.
Two major problems exist with the current state of floodplain mapping in Houston and Harris County: 1) existing maps are obsolete but are still being used at the state and federal level, and 2) the updated NOAA Atlas 14 is still not reasonable or dependable — our actual 100-year rainfall is much larger than identified in that document.
Existing Floodplain Maps Are Obsolete
The current official floodplain maps for Harris County, published in 2007 and updated occasionally thereafter, are obsolete. As indicated above, both Harris County and the city of Houston have abandoned the existing 100-year floodplain and are using the 500-year floodplain as the standard for regulatory purposes. However, state and federal government agencies continue to use the 2007 regulatory floodplains.
Obsolete Maps Are Being Used for Important Public Works. Consider, for example, the Texas Commission on Environmental Quality (TCEQ) and Environmental Protection Agency (EPA) rules governing siting of wastewater treatment facilities:
"(a) If a 100-year flood plain is located within 1,000 feet of the site of a wastewater treatment facility, the 100-year flood plain must be shown on the site plan. A flood plain determination must be based on a superimposition of the 100-year flood elevation on the most accurate available topography and elevation data for the site.
(1) A 100-year flood plain must be based on the Federal Emergency Management Agency (FEMA) Flood Insurance Study in effect at the time the plans and specifications are submitted to the executive director. FEMA maps are prima facie evidence of flood plain locations." [emphasis added]
Those requirements are followed throughout the TCEQ and EPA regulatory process for hazardous waste, solid waste disposal areas, and industrial siting — dangerous land uses the siting of which should be based upon the best available information.
This also has serious consequences for new highways and Corps of Engineers’ regulatory projects. These projects will be evaluated using obsolete data, and FEMA is unable to change these maps quickly enough to keep up with the increasing storm intensity. Indeed, work has been ongoing for several years on the new Harris County floodplain maps, and they will need to be updated again soon after arrival.
FEMA Floodplain Map Process. The process involved in the issuance of official floodplain maps by FEMA is a lengthy one. As we discuss below in New Floodplain Maps Will Be Obsolete, new floodplain maps are being prepared by Harris County Flood Control District in partnership with FEMA, under a program known as MAAPnext. These maps 1) must be completed, 2) issued as proposed map changes and subjected to public review and comment, and 3) issued in final form after consideration of the comments. The time involved means that it may well be late 2024 before we have new official maps. In the meantime, many projects could be built based on obsolete floodplain requirements at the state and federal level.
Until these new maps are issued, Harris County and the city of Houston will continue to use the existing 500-year floodplain map (see Figure 1) and also require that new construction be 2 feet above this flood elevation. This map shows about 40% of Harris County being in the floodplain, and it is likely that in the forthcoming map revisions, the new 100-year floodplain will be similar to the existing 500-year floodplain.
Challenges to the 500-year requirement. The city of Houston’s use of the 500-year requirement for new development was challenged in court proceedings as going further than the federal flood insurance requirements and therefore representing an unconstitutional “taking” of property. In this case, the First District Court of Appeals of Texas recently upheld the city’s new regulatory approach. However, a later decision in Dallas made a contrary ruling that a taking occurred in a similar situation and that the 2001 FEMA floodplain map would apply as opposed to the later floodplain boundaries imposed by the city. Given the apparent conflict between these two cases, it is likely that the Texas Supreme Court will be writing on this issue in the not-too-distant future.
New Floodplain Maps Will Be Obsolete
There are two principal areas of concern regarding the forthcoming floodplain maps:
- Although they will be based on 100-year and 500-year rainfall events updated as per Atlas 14 prepared by the National Oceanic and Atmospheric Administration (NOAA), the rainfall totals included in Atlas 14 are already out of date as they do not rely on correct, complete data and do not account for climate change.
- The computer model being used to create these maps is known as HEC-RAS, and that model will also produce additional, non-regulatory floodplain information about off-stream flooding (which is not related to creeks and bayous overflowing their banks). This new information will be very important and useful but potentially confusing and must be fully and carefully explained by our flood officials. See the discussion of Unique Issues Regarding HEC-RAS for more detail.
Issues With Atlas 14 Rainfall Amounts. NOAA published Atlas 14 a year after Harvey, intending it to inform updates to infrastructure design and floodplain regulations that had been established using outdated rainfall estimates developed in the 1960s. On its face, NOAA Atlas 14 represented a monumental increase in the Houston area 100-year rainfall event. As can be seen from the chart below, Atlas 14 substantially increased the 100-year and 500-year storm amounts for the Houston area, raising the 100-year event for 24 hours (the time period used for floodplain mapping purposes) from 13 inches to 17-18 inches and the 500-year event from 18.9 to 25.4 inches. These represent about a 30% to 35% increase in these rainfall totals — a significant amount.
Figure 4 — Comparison of NOAA Atlas 14 Rainfall Amounts to Previous Amounts
Unfortunately, it seems clear that these Atlas 14 rainfall amounts, although much higher than the previous evaluation, are still lower than today’s reality as shown by the additional storms in Figure 4. The 100-year rainfall estimates for the Houston region would be higher if NOAA’s analysis included more complete information. For example:
- NOAA’s analysis used only 25 inches of rain in 24 hours for the 1979 Tropical Storm Claudette record rainfall amount, whereas 43 inches is recognized as the actual amount.
- No adjustments were made by NOAA to account for any climate change trends.
- The rainfall from Tropical Storm Imelda (20-40 inches) is not included in the Atlas 14 statistics.
Thus, even though the 100-year 24-hour rainfall amounts for the Houston area went from the previous 13 inches to 17 inches with the NOAA Atlas 14 update, if current conditions were truly reflected in these statistical rainfall analyses, our 100-year rainfall would likely be 24 inches or higher in 24 hours.
This issue regarding Atlas 14 emphasizes a continuing problem with statistics and climate change. Our rainfall amounts are becoming more intense. The statistical base is continually changing. This is perhaps the biggest challenge of climate change — the inability of our current tools to address the changing statistical base in a timely manner. This will affect sizing of drainage systems in industrial and residential settings as well as larger questions of floodplain mapping and remapping. Until we develop effective tools, we will always be trying to catch up with these changing rainfall amounts and the resulting flood levels.
Unique Issues Regarding HEC-RAS. A computer model that has not previously been used to formulate regulatory floodplain maps will be used to generate the new HCFCD/FEMA floodplain maps currently under development. This model is the Hydrologic Engineering Center’s River Analysis System, otherwise known as HEC-RAS. Until this round of floodplain mapping, the floodplains displayed on official maps were only based upon creek or bayou flooding from the channel outward. However, there are many areas in Houston that flood because of the inability to gather water and remove it to the bayous and creeks. During Harvey, just about 75% of the home flooding occurred in areas outside the FEMA 100-year floodplain.
The HEC-RAS model has the ability to predict this off-stream flooding from the pattern of stormwater overland flow as well as predicting flooding coming from the stream channel. From information released to date, the new floodplain maps will display off-stream flooding areas for informational purposes only — and it will not be used for building regulations because of FEMA mandates. Nevertheless, this information will become very important to urban planners and home buyers in real estate sales disclosures.
This off-stream flooding information has not been previously available and will likely be controversial. The use and understanding of this new floodplain information will be an important part of Houston’s maturing as a community learning to live with water. While this is an excellent upgrade in the level of information that will be available to our citizens, it will also create new problems and issues.
Addicks and Barker and the Northeast Sector of Houston/Harris County: The Need to Integrate Equity
Equity in flood control has become an important issue post-Harvey, and it has only intensified as each year passes. FEMA defines equity as “The consistent and systematic fair, just and impartial treatment of all individuals.”
In 2018, the Harris County flood control bond issue included projects in every watershed along with a promise of equity in the provision of bond funding to all areas of the county. The language of the bond states:
"Since flooding issues do not respect political or jurisdictional boundaries, the Commissioners Court shall provide a process for the equitable expenditure of funds, recognizing that project selection may have been affected in the past and may continue to be affected by eligibility requirements for matching federal, state, and other local government funds."
This provision recognizes a key aspect of equity, namely that it does not mean equality of allocation of funds but rather requires addressing the cumulative effects of decades of unequal allocation of state, federal, and local resources. And equity is a dominant issue in discussions of the northeast portion of the city and county.
Perhaps no issue is more difficult than equity. A post-Harvey comparison of the Addicks-Barker area and the northeast sector of Houston/Harris County brings this equity issue very clearly into focus. The Addicks and Barker area is wealthier than the northeast part of town, as can be seen on Figure 5. In the following sections, the current flooding situation is detailed for these two areas, as well as the proposed next steps for flood control and how these will lead to a major debate about equity.
Figure 5 — 2019 Percent of Population in Poverty by Block Group in Harris County
Addicks and Barker Reservoirs
During Harvey, major flooding occurred both upstream and downstream of the Addicks and Barker reservoir dams. Our discussion here focuses only on the upstream situation.
When Addicks and Barker were originally being constructed, controversy broke out over land condemnation for these projects and the decision was made to condemn only a portion of the flood pool that would result from Addicks and Barker being filled to capacity. Over time, most of the private property within the flood pool was developed. During Harvey, about 10,000 of the approximately 20,000 homes in the flood pool were flooded. The area flooded during Harvey, as well as the government-owned land and the full extent of flood pool development, are shown in Figure 6.
Figure 6 — Addicks and Barker Reservoirs: Harvey, Land Ownership, and Flood Pool Development
“Unconstitutional Taking” Litigation after Harvey. Shortly after Harvey, multiple lawsuits were filed in the Federal Court of Claims in Washington alleging an unconstitutional taking of property by the federal government, on the basis that it had created a flood pool without compensating the owners of the land. These claims were consolidated and tried in two phases. In the first phase, Judge Lettow of the Court of Federal Claims determined that a permanent flood easement had been inversely condemned by the federal government. In the second phase, he determined the just compensation for the six test cases that were tried. When the awarded compensations for these test cases are applied across the entirety of the flooded area, the government could be liable for billions of dollars for having taken a permanent flood easement from the affected property owners.
Financial Repercussions Beyond the Private Losses. Although the governmental liability is quite large, there are many repercussions beyond these private losses. Of particular concern is the fact that these flooded homes provide much of the tax base for a number of taxing entities, such as school districts, county agencies, and cities, including various types of utility districts that were formed to assist the developers in financing and constructing water, sewer, and drainage systems. In turn, this loss of tax base may threaten the viability of bonds that have been issued to finance these developments. And if the bonds fail, there may be many different collateral impacts, including malpractice claims against engineers and lawyers working for these districts. This risk is sufficiently real that an amicus brief to intervene in the Federal Court of Claims litigation was filed by several of these utility districts based on their concern of bond failure.
The Corps of Engineers and Harris County Flood Control District are currently reexamining alternative approaches to the flooding within Addicks and Barker Reservoirs. Interestingly, buyout is not being seriously considered, at least in part because of the implications of a buyout on bonded indebtedness.
Formation of Houston Stronger. In the past, the federal government, knowing the situation of the potential for flooded homes as well as structural issues with the Addicks and Barker dams, undertook a study of options for reservoir improvements: It concluded in an interim report that the risk of a storm such as Harvey was too remote to justify a federal project that would address the home flooding issues within the reservoir — an example of the failure of the Corps of Engineers to adjust its procedures to cope with the changing nature of these storms influenced by climate change. In February 2023, HCFCD and the Corps announced their agreement to collaborate on furtherance of this study, with HCFCD taking the lead on additional analysis of study alternatives as well as contributing additional funding and technical assistance.
Faced by the inability of the Corps to act, a group called Houston Stronger was formed to address the Addicks and Barker situation by private sector action. Engineering firms were recruited and developed a number of alternative proposals.
- A huge tunnel system to take inflows entering Addicks and Barker dams and drain them underground some 30 miles eastward to the Houston Ship Channel/Galveston Bay.
- Improvements to trap water before it enters Addicks and Barker.
- Plans to increase the storage capacity within Addicks and Barker.
Houston Stronger’s preliminary proposed flood improvements are shown in Figure 7.
Figure 7 — Houston Stronger’s Plans To Alleviate Flooding Around Addicks and Barker Reservoirs
Litigation Needs to Be Used as a Policy Tool. This situation is very difficult to resolve. On the one hand, there is litigation that is not related to problem-solving but rather seeking financial recovery. On the other, there is a sincere desire to address a situation that is likely to recur over time, hence the permanent easement ruling by the court. The only governmental entity with jurisdictional footing in both the lawsuit and the dam maintenance and construction is the U.S. Army Corps of Engineers. However, the Corps has chosen to maintain separation between the court proceedings and their Addicks/Barker federal project studies, because among other reasons, legal strategy would caution against making statements on public events that could be used against them in litigation. This approach, from an outside perspective, seems counterproductive. In retrospect, governmental entities such as Harris County or the utility districts perhaps should have intervened in the private litigation to put forward the local government’s policy position, but they did not. (Fort Bend County did file its own lawsuit against the Corps of Engineers under an Administrative Procedures Act claim after Harvey, regarding the operations of the Barker Dam during Harvey.)
One of the many lessons learned post-Harvey is that legal intervention is one of the tools available, and it should be more widely used. Litigation as a policy tool is certainly reasonable when the stakes of litigation are so high.
The Northeast Sector of Houston and Harris County
The northeast sector is bounded by Interstate Highway 45 on the west, Beltway 8 on the north and east, and Buffalo Bayou on the south (see Figure 8). The majority of this area is drained by Greens and Halls Bayous, with the Fifth Ward and Pleasantville draining into the Buffalo Bayou/San Jacinto River watershed.
Figure 8 — Harris County Watersheds and Waterways
In Figure 9, a close-up of the northeast sector shows these key bayous and their floodplains along with key roads and railroads. According to this map, 23,804 acres are in the 100-year floodplain and 41,790 are in the 500-year floodplain. Although this map is official, it is out of date as noted in New Floodplain Maps above. It is very likely that upward of 40,000 acres will be in the forthcoming 100-year floodplain — almost as large as the current 500-year floodplain.
Figure 9 — Northeast Houston Railways and Floodplains
However, the floodplain map does not begin to tell the story of flooding in this northeast part of town.
- During Harvey, Greens and Halls Bayous had about 25,000 flooded homes combined, the most in Harris County. Hunting Bayou suffered about 7,400 flooded homes, a higher proportion of flooded homes to population than any watershed in Harris County, with Greens not far behind. By way of contrast, in Brays Bayou, the most populated watershed, almost 24,000 homes were flooded.
- During Allison, over 28,000 residences flooded within Greens and Halls watersheds. Hunting Bayou experienced flooding of over 8,000 residences. More than 6,000 residences flooded in Brays Bayou watershed during Allison.
In other words, the northeast community was hit disproportionately hard during Harvey as well as earlier during Allison. (Similar disparities also occurred during Imelda).
Flawed Benefit-Cost Analysis Leads to Lack of Federal Funds. Despite these statistics, the Greens and Halls Bayou watersheds have never qualified for a major federal flood control project, although many other urban bayou systems such as Brays, White Oak, Sims, Hunting, and Buffalo have all received federal assistance. And it is not because there is no damage, but rather because of the way federal funding is determined, based on benefit-cost analysis. Simply stated, poorer watersheds such as Greens and Halls have many lower cost structures whose flood damages simply do not support the high cost associated with major flood damage reduction projects, regardless of the actual number of flooded homes. That provision of the federal regulatory structure is failing Houston and likely many other areas of the country.
Harris County Bond Funding Delays. In addition to the failure of the federal government to come to the aid of Greens and Halls Bayous, there was a problem with the initial allocation of Harris County bond funds. The breakdown of the split of the $2.5 billion bond issue is shown in Figure 10 — the pink line indicates the amount of proceeds received from the bond issuance, while grey and yellow indicate funds from other sources. In the case of Greens and Halls Bayous, the bulk of the funding (the yellow line) was to be provided from federal funds that had to come through the Texas General Land Office. This money has been held up for several years, meaning the majority of the funding promised to Greens and Halls Bayous has not been available in a timely manner. While Harris County eventually allocated additional funding to remedy this, other watersheds that received bond funds much sooner were able to move forward more rapidly.
Figure 10 — 2018 Bond Program: Funding Allocation by Watershed
This alone does not necessarily mean that the bond proposal was inequitable, although it perhaps should have raised red flags. The shortfall of funding was remedied with the recent allocation of Disaster Recovery and hazard mitigation funds to HCFCD, which worked out to about 25% for each precinct. However, now Houston Stronger has made a powerful case for the Corps of Engineers to provide Addicks and Barker with protection from a Harvey-level storm, while Greens and Halls Bayou watersheds still have no firm proposal to protect them from such a storm.
The bottom line is that the northeast area needs a major protection plan much like that being proposed for Addicks and Barker Reservoirs. Unfortunately, they do not have the resources to bring engineering and lobbying assistance as Houston Stronger did. Instead, the community will need to mobilize in support of a major flood abatement program for Greens and Halls Bayous.
For example, one solution offered in the report “A Proposal for Equitable Flooding Solutions in Northeast Houston” is that a number of interconnected tunnels could be constructed to alleviate obstructions caused by major road and railroad intersections, draining to the San Jacinto River and into Galveston Bay (see Figure 11). Solutions like this are currently being assessed by HCFCD in a “Feasibility Study of Stormwater Conveyance Tunnels.” The second phase of the feasibility study, released in June 2022, included a social vulnerability screening and indicated that a potential tunnel system could be a highly effective option for reducing flooding in the more densely populated areas of Harris County.
Figure 11 — Northeast Houston Tunnel Drainage Outlet Concept
Harris County is currently studying a tunnel system for Addicks and Barker reservoirs, but also for other watersheds throughout the county. Hopefully this study will lead to some much-needed flood reduction for the northeast part of the county.
Coastal Flood Protection
As we noted at the outset, hurricane surge flooding is different from rainfall or riverine flooding. It is violent and highly destructive of life and property. If you are in structures in the path of surge flooding, there is a very real chance that you could perish in the storm. And the extent of damages from such a surge event will be beyond anything the Houston area has experienced. We have been lucky so far. A big surge has not hit Houston since Carla back in 1961, although Ike in 2008 would have killed thousands and destroyed much of our refinery and chemical complex if it had come ashore 40 miles further south — a very near miss. The risk is enormous, and the current planning is simply not adequate.
Next, we examine two aspects of coastal flood protection. First, what can be done in the short term? Second, what are the long-term solutions?
Abating the Current Risk
Two important planning concepts to abate the current risk are under development. However, it is likely that substantial protection will not be completed for 10 to 20 years and there is a very good chance of a major surge event in the Houston area during that time period. Very little public discussion has occurred about what could or should be done in the interim to reduce the potential damage of such an event.
Securing the Industrial Complex is Vital. A major surge event would cause incredible economic and ecological damage along the Houston Ship Channel. Jamie Padgett of the Rice University Department of Civil and Environmental Engineering studied the effect of surge levels upon the Houston Ship Channel industrial complex and determined that a surge event of 24 feet would flood about 2,000 storage tanks and cause the spill of about 90 million gallons of oil and hazardous substances. This spilled product would first travel in with the surge to predominantly minority communities in Houston and channel cities such as Galena Park. Then it would flow back into Galveston Bay, creating the worst environmental disaster in United States history.
The general consensus is that the Houston Ship Channel industrial complex can handle a 15-foot surge without major damage. Floodplain maps indicate that hazardous waste storage and various designs should be constructed to flood levels in the 18- to 20-foot range. However, there is no doubt that massive harm would result from a 24-foot surge.
How to Protect Storage Tanks. An appropriate entity needs to take the lead in working with the industrial community to develop coordinated responses to this major economic and environmental threat. First, many questions need to be asked and answered:
- Should industry drain storage tanks or fill them prior to the surge event?
- Is there consensus on this issue?
- How will the tank contents be evacuated? By truck or by pipeline?
- Are all storage tanks secured against rising water? (This is generally not a design consideration for such tanks.)
- Is there general agreement on the timing of the shutdown of industrial operations prior to an incoming storm?
- Can additional levee protection be constructed around the more vulnerable facilities?
How to Secure Container Storage. Additionally, there is the issue of container storage. There are major container storage facilities near the bay, with two major container ports at Morgan’s Point and Bayport.
- How secure are the container storage facilities within and adjacent to these major ports?
- Are there any requirements for securing these containers against rising waters?
- Is there an inventory of these facilities?
To date, the issue of securing the industrial complex has not received much attention: It has been overshadowed by the plans for long-term, massive protection projects. But we must act in the short term as well as the long term.
Two major, complementary projects are under development as longer-term solutions. Both are absolutely needed to protect the vulnerable eastern shoreline of Harris County with its extensive residential and industrial development.
- The Corps of Engineers has developed the coastal barrier project that is focused on providing an initial line of defense along the coast.
- The Severe Storm Prediction, Education, and Evacuation from Disaster (SSPEED) Center at Rice University has recently been funded to conduct further investigations on the Galveston Bay Park Plan — this is intended to be complementary to the coastal barrier as an additional in-bay protection system.
Both these projects are crucial to securing the region from surge flooding from bigger Category 3, 4, and 5 hurricane events. In the next sections we will address two important issues that arise in designing these projects:
- The design storm for the coastal barrier.
- The tiered environmental impact statement.
Design Storm Issues. The Corps’ coastal barrier project sets up an initial line of defense along Galveston Island and the Bolivar Peninsula. The key components of this project are a double tier of sand dunes built to a maximum of 14 feet on the west end of Galveston Island and on the Bolivar Peninsula; a gate structure across the pass between Bolivar and Galveston built to about 22 feet in elevation; an increase in the height of the Galveston sea wall to about 21 feet; and a backside levee around the city of Galveston. This plan also includes two gates inside the bay on Dickinson Bayou and Clear Lake to provide some protection for residential development on these watercourses.
Although this protective barrier is very important, it has only been designed to stop the surge from, at most, a Category 2 storm. This is because the Corps’ regulations limit the calculation of benefits to a foreseeable 50-year time period, and the statistical basis used by the Corps results in the 50-year storm surge being no larger than a weak to mid-level Category 2 storm with 14 feet of surge. In fact, a 14-foot surge is substantially lower than the 20 to 22 feet anticipated from modeling of FEMA hypothetical Storm 36 (which is a weak Category 4 storm with max winds of 134 mph) and much less than that generated by a Category 5 storm.
Galveston Bay Park Plan. SSPEED Center modeling of a Category 5 storm with the coastal barrier in place indicates that significant flooding would occur in Kemah, Seabrook, Shoreacres, LaPorte, and Baytown, as well as in the Houston Ship Channel and the Bayport Industrial complex. It is likely the damage would easily exceed $100 billion, and there would be massive ecological damage resulting from the spilled oil and hazardous chemicals discharging into Galveston Bay.
The SSPEED Center has proposed the construction of the Galveston Bay Park Plan to address the absence of flood protection for eastern Harris County, eastern areas of the city of Houston along the Houston Ship Channel, and Buffalo Bayou including the lower portions of Greens, Hunting, Sims, and Brays Bayous (see Figure 12). The concept is to build an earthen barrier (with recreational amenities) along the Houston Ship Channel from Houston Point in Chambers County to the Texas City levee system in Galveston County using dredged material from the Port of Houston’s Project 12 (the proposed deepening of the Houston Ship Channel). As well as providing a storm surge barrier, this flood protection project would provide navigational improvements needed by the port and recreational park space that is not currently available in Galveston Bay. Environmental enhancement, including beneficial use of dredged material, marsh planning, bird habitat and recreational amenities will also be incorporated.
Figure 12 — The Galveston Bay Park Plan
As of August 2023, the SSPEED Center is moving forward on a Phase 2 study to determine the engineering and economic feasibility of this park plan for Galveston Bay. This work is being pursued outside of the Corps of Engineers’ and the federal planning process, and is funded by four parties that came together and donated $250,000 each: the Port of Houston Authority, Harris County Flood Control District, the city of Houston, and Joe Swinbank, a private entrepreneur. The goal of this work is to protect the extensive residential and industrial development in eastern Harris County that is largely unprotected by the Corps’ Texas Coastal Barrier project, particularly relative to larger storm events.
The basic concept is that this project would be proposed by a non-federal entity and permitted, but not paid for, by the U.S. Army Corps of Engineers. In this way, protection for eastern Harris County could be secured in spite of the limitations of the Corps of Engineers’ benefit-cost approach. As a locally preferred “in bay” alternative, it would require environmental review. This possibility is discussed below: See The Tiered Environmental Impact Statement Process.
Importantly, this project is likely a forerunner of the type of additional flood protection that every coastal city in the United States will require in the future. The Galveston Bay Park Plan proposes to build protection against a Category 5 storm that simply cannot be economically justified under current Corps of Engineers’ rules and regulations. This local add-on could become a part of the federal project as a locally preferred alternative, with the difference between the cost of this project and the Corps’ proposed gates on Dickinson Bayou and Clear Lake being provided by local funding. This do-it-yourself add-on will be essential to the protection of the Houston Ship Channel and eastern Harris County. It will also protect the community on the eastern side of the city of Houston, an important equity issue.
The Tiered Environmental Impact Statement Process
The National Environmental Policy Act requires an environmental impact statement for major and significant federal projects. When the coastal barrier project was under development by the Corps of Engineers, it became clear to Corps planners and environmental scientists that it was not possible to address all environmental issues of concern arising from the various project pieces in a single environmental impact statement. Rather than attempting to undertake this basically impossible task, the Corps wisely decided to “tier” the environmental impact analysis. This means that each project component will be evaluated in its own environmental impact document. An advantage of the tiered approach is that it offers the opportunity for the Galveston Bay Park Plan to be introduced as an alternative to the Dickinson and Clear Lake gates.
To date, the Corps has published an overall environmental assessment document that essentially sets out the database and the proposed projects that will be subject to further analysis in the subsequent environmental impact documents (referred to as the “Tier Two environmental analysis”).
Tier Two Environmental Analysis of Each Project. Each of the proposed projects has its own unique environmental issues. Of particular concern is the impact of the Bolivar Roads gate structure on circulation patterns and the tidal prism and navigation within the Galveston Bay system. There are endangered species issues — sea turtles and piping plovers — related to the dune construction and beach expansion, as well as landowner impact issues. The routing of the backside levee and its impact on Galveston Island traffic flows and subdivisions will also generate issues, as will the question of alternative ways to protect the areas adjacent to the western shoreline of Galveston Bay.
This second round of environmental review will be required before the Corps is legally able to seek congressional construction funding. The length of time that these projects require will continue to generate frustration. Indeed, there have been rumors that some political supporters of this project are seeking to exempt it from further environmental review. While such exemptions have occurred in the past for a very few projects, the scope and extent of the environmental issues in this project serve as an argument that these Tier Two analyses will help the Corps to design much better projects.
This coastal barrier project, if constructed as proposed, would be the largest public works project in the Corps of Engineers’ history. The gate structure across Bolivar Roads would be the largest in the United States and possibly the world. This is a huge proposal, and the engineering and planning required is monumental in scope and complexity. This is not an easy project to either design or build. And it will require time.
Despite the complexities of the project, this tiered approach certainly offers the opportunity for the Galveston Bay Park Plan to be introduced as an alternative to the Dickinson and Clear Lake gates. This may become the preferred pathway for the next phase of development of the Galveston Bay Park Plan, which is absolutely needed in order to offer Harris County and the city of Houston — as well as Baytown, Seabrook, Kemah, Shoreacres, and LaPorte — protection from the next big storm.
Houston and Harris County have had massive flooding problems in the recent past, and we all know a huge storm is coming in the future — we just don’t know when. We have the ability to adapt and make the changes needed to survive going through the 21st century, but we have much work to do. Here are the key items to address going forward:
- Meet the Challenges of Climate Change. We must get in front of climate change. We need to consult experts like Philip Bedient and other academics and government experts to help us identify the rainfall levels and hurricane intensity that we need to plan for. We need to educate our people about our changing climate and changing rainfall patterns. We should all know and understand these changes.
- Develop Tools for Stormwater Engineers and Planners. We must develop tools that aid engineers and planners in understanding our changing rainfall patterns and help them make better design decisions regarding stormwater management.
- Educate People About Flooding. We must educate our people about flooding and the risk that it poses. Many of our citizens do not know what watershed they live in. It is impossible to be well informed about flooding if you do not know which watershed to look to for flooding information. Civic awareness is crucial.
- Learn To Live With Water and Communicate Flood Risks. We must learn to live with water and tell the truth about flooding and our flood risks. We need markers showing historic flood levels and anticipated flood levels. All citizens living in hurricane surge zones should know the risks of living in those areas. All citizens living in floodplains should know the risks of living in those areas. We cannot live with water without understanding the risk that is posed by water.
- Establish Comprehensive Flood Warning System. If we are to live with water, we will need a comprehensive flood warning system. We should have several ways of contacting citizens to communicate information about flooding risks. We should have user-friendly apps for our mobile devices that issue warnings and show preferred evacuation routes and streets that fare better during heavy rain. We need to help our citizens survive flooding.
- Buy Out At-Risk Homes. We need to buy out tens of thousands of homes over time with a knowledge and consideration of the social impacts of buyouts and with measures in place to remedy inequalities.
- Fund Buyouts for Flooded Homes. We need a reserve of funding available to buy out homes when flooding occurs. That is when homeowners are most willing to sell, and that is when we must be ready with fair offers.
- Integrate Housing and Buyout Plans for High Flood Risk Areas. We should begin to integrate new housing plans with buyout plans. We know the areas where we expect to see major flooding in the future. We should have housing plans underway in all areas where major flood damages are expected.
- Identify Lowest Flooding Risk Areas. If we are to live with water, we need to identify the areas with the lowest risk of flooding — those areas that fare better during heavy events than others.
- Use Metrics to Compare Watershed Protection. We need metrics to be able to compare the level of flood protection and/or abatement that is available in each watershed. Which watersheds perform adequately during a 5-year storm? A 10-year storm? A hundred-year storm? In many respects, it does not matter what level of event is being evaluated as long as the same measure is used in every watershed for comparability purposes.
- Provide Equitable Relief to Greens and Halls Bayous. From an equity perspective, significant relief needs to be provided to Greens and Halls Bayous as soon as possible. A major underground drainage system should continue to be seriously evaluated for this area of the city and county. Phase 3 of HCFCD’s Feasibility Study of Stormwater Conveyance Tunnels is to begin in Spring 2023 and must continue to address and consider social vulnerability concerns. For too long, this northeastern Houston area has received less than its fair share of flood improvements, a situation that will only be exacerbated as wealthier watersheds receive federal assistance, while the relatively poorer Greens and Halls Bayou watersheds receive no or limited federal support. To the extent that the deficiencies in the Corps of Engineers’ benefit-cost analysis system cannot be altered, we must make up the difference in the allocation of local funding.
- Deal With Friction Between Flooding Authorities. Substantial effort needs to be made to address the friction between state and local flooding authorities. The problems that arose from the passing of HUD funding through the Texas General Land Office to Harris County and the city of Houston hurt many areas that were promised that money in local plans. Flood relief should not be a political football. The recent cooperation of the city of Houston, Harris County, the GLO, and HCFCD in the allocation of disaster relief and mitigation funding is encouraging in that regard.
- Protect Eastern Harris County with Galveston Bay Park Plan. Harris County is a coastal county that is not adequately protected by the Corps of Engineers’ planned coastal barrier: It offers only limited relief. In addition to the coastal barrier, the Galveston Bay Park Plan should be pursued to offer protection against Category 3, 4, and 5 storms to the eastern sector of Harris County and the Houston Ship Channel/Bayport industrial complex. Without such protection, there is a significant risk of catastrophic economic and environmental damage that will only grow as climate change increases the risk of larger hurricanes.
There is nothing easy about this list of to-do items. It will take hard-nosed leadership and science, engineering, and planning skill. We need to hire the best minds and give them excellent directions. These tasks can be mastered, and they must be for Houston and Harris County to survive the rest of the 21st century and beyond.
The new leadership of Harris County Flood Control District offers a major ray of hope. Director Tina Petersen comes from outside the district. She is not wedded to existing policies and seems open to new and bold ideas. In early 2023, she took the time to attend a citizen meeting in the northeast part of town one workday evening — prior directors had required the citizens to come to district headquarters.
We need leadership capable of meeting the great challenges that we face, and Tina Petersen has already made a great initial contribution in this regard. Her willingness to go into hard-hit areas and meet the citizens on their turf is an indication of change within the HCFCD — change that gives us hope that the future might be different from the past.
 Harris County is the third most populous county in the U.S., with over 4.7 million people. Houston is the county seat.
 Cat Cardenas and Brandon Formby, “Houston council approves changes to floodplain regulations in effort to reduce flood damage,” Texas Tribune, April 4, 2018, https://www.texastribune.org/2018/04/04/houston-city-council-approves-changes-floodplain-regulations-narrow-vo/.
 National Oceanic and Atmospheric Administration, “NOAA updates Texas rainfall frequency values.,” September 27, 2018, https://www.noaa.gov/media-release/noaa-updates-texas-rainfall-frequency-values.
 Office of the Texas Governor, “U.S. Army Corps Of Engineers Announces Nearly $5 Billion For Disaster Recovery Projects In Texas,” July 5, 2018, https://gov.texas.gov/news/post/u.s.-army-corps-of-engineers-announces-nearly-5-billion-for-disaster-recovery-projects-in-texas.
 The Texas General Land Office, “HUD Approved GLO’s Mitigation Action Plan Granting $750 Million Directly to Harris County and $488 Million for the Houston-Galveston Area Council for Regional Projects,” press release, March 18, 2022, https://www.glo.texas.gov/the-glo/news/press-releases/2022/march/hud-approved-glos-mitigation-action-plan-granting-750-million-directly-to-harris-county-and-488-million-for-the-houston-galveston-area-council-for-regional-projects.html.
 The Texas General Land Office, “Under Commissioner Buckingham’s New Plan, Houston and Harris County Achieving Success With Disaster Recovery and Mitigation Funding,” press release, June 19, 2023, https://www.glo.texas.gov/the-glo/news/press-releases/2023/june/under-commissioner-buckinghams-new-plan-houston-and-harris-county-achieving-success-with-disaster-recovery-and-mitigation-funding.html.
 Dylan McGuinness, “Houston will maintain the city's open ditches again, reversing a policy that put onus on residents,” Houston Chronicle, June 7, 2023, https://www.houstonchronicle.com/politics/houston/article/houston-open-drainage-ditch-policy-reversed-18140084.php.
 Harris County Office of County Administration, “Harris County Names Experienced Leaders in Key Positions,” https://oca.harriscountytx.gov/Newsroom/harris-county-names-experienced-leaders-in-key-positions, accessed July 27, 2023.
 Amy McCaig, “Rice experts available to discuss 5th anniversary of Harvey,” Rice University News and Media Relations Office of Public Affairs, August 16, 2022, https://news.rice.edu/news/2022/rice-experts-available-discuss-5th-anniversary-harvey.
 This storm’s designation as a 250-year storm is based on old statistical analysis and does not necessarily reflect the current status.
 FEMA and Harris County Flood Control District, Off the Charts: Tropical Storm Allison Public Report, 2001: 14, https://www.hcfcd.org/Portals/62/Flooding%20and%20Floodplains/ts-allison_pubreportenglish.pdf?ver=2020-01-06-101710-540.
 A “100-year flood” interval means that a flood of that size has a 1% chance of occurring in any given year: https://www.usgs.gov/special-topics/water-science-school/science/100-year-flood.
 Willem Jan Goossen, “Interview — The Dutch make room for the river, European Environment Agency,” May 11, 2021, https://www.eea.europa.eu/signals/signals-2018-content-list/articles/interview-2014-the-dutch-make.
 An op-ed by one of the authors of this paper on Houstonians living with water was published in the Houston Chronicle in April 2018, about six months after Harvey, laying out the general concept that we have had in the past and how in the future huge rainfalls cannot be controlled but must be accommodated: Jim Blackburn, “Blackburn: Harris County residents need to learn to live with water [Opinion],” Houston Chronicle, April 2, 2018, https://www.houstonchronicle.com/opinion/outlook/article/Blackburn-Harris-County-resident-need-to-learn-12800172.php.
In addition, the New Orleans design firm of Waggoner and Ball wrote a report for the City of Houston titled "Living With Water" in 2020: City of Houston, Living With Water Final Report, https://reduceflooding.com/wp-content/uploads/2020/02/Living-With-Water.pdf. Curiously, the authors indicated that they had trademarked the phrase which seems a bit much for such a common usage combination of words.
 Lise Olsen, “Record reservoir flooding was predicted even before Harvey hit Houston,” Houston Chronicle, February 22, 2018, https://www.houstonchronicle.com/news/houston-texas/houston/article/barker-addicks-dams-flooding-predicted-army-corps-12632041.php.
 Katharine Shilcutt and Roxanna Asgarian, “The Deliberate Flooding of West Houston,” Houstonia Magazine, October 16, 2017, https://www.houstoniamag.com/news-and-city-life/2017/10/barker-addicks-reservoirs-release-west-houston-memorial-energy-corridor-hurricane-harvey.
 Harris County Flood Control District, “Z-09 Harris County Flood Warning System,” https://www.hcfcd.org/Resources/Storm-Center/Flood-Warning-System.
 Understanding Houston, 2021, “Natural Disaster Risks in Houston,” https://www.understandinghouston.org/topic/disasters/disaster-risks#flooding_risks.
 David Hunn, Matt Dempsey, and Mihir Zaveri, “Harvey's floods: Most homes damaged by Harvey were outside flood plain, data show,” Houston Chronicle, March 30, 2018, https://www.houstonchronicle.com/news/article/In-Harvey-s-deluge-most-damaged-homes-were-12794820.php.
 Laura Thompson, “Buyouts Bring Promise and Challenges to Flood-Affected Homeowners,” Rice University Kinder Institute for Urban Research, August 20, 2018, https://kinder.rice.edu/urbanedge/buyouts-bring-promise-and-challenges-flood-affected-homeowners.
 42 U.S.C. 4012a.
 Mike Morris, “Houston City Council unanimously backs plan to build homes in flood plain,” Houston Chronicle, April 26, 2018, https://www.chron.com/news/houston-texas/houston/article/City-Council-unanimously-backs-plan-to-build-12863712.php.
 See Houston, Texas, Code of Ordinances ch. 19, arts. I–V (2018), https://library.municode.com/tx/houston/codes/code_of_ordinances?nodeId=COOR_CH19FL.
 National Oceanic and Atmospheric Administration, NOAA updates Texas rainfall frequency values,” NOAA media release, September 27, 2018, https://www.noaa.gov/media-release/noaa-updates-texas-rainfall-frequency-values.
 City of Houston v. Commons of Lake Houston, Ltd., No. 01-21-00369-CV, 2023 Tex. App. (Tex. App. Jan. 12, 2023), https://casetext.com/case/city-of-hous-v-the-commons-of-lake-hous.
 The City of Dallas v. Millwee-Jackson Joint Venture, No. 05-20-00611-CV, 2023 Tex. App. LEXIS 783 (Tex. App. Feb. 8, 2023), https://casetext.com/case/the-city-of-dallas-v-millwee-jackson-joint-venture.
 David Hunn, Matt Dempsey, and Mihir Zaveri, “Harvey's floods: Most homes damaged by Harvey were outside flood plain, data show,” Houston Chronicle, March 30, 2018, https://www.houstonchronicle.com/news/article/In-Harvey-s-deluge-most-damaged-homes-were-12794820.php.
 Jen Rice, “New Harris County flood maps will be first in US to show more accurate risks for homes, businesses,” Houston Chronicle, March 4, 2023, https://www.houstonchronicle.com/politics/houston/article/harris-county-flood-maps-floodplain-risk-17762023.php.
 FEMA, “FEMA Defines Equity in its Mission of Making Programs More Accessible,” press release, September 9, 2021, https://www.fema.gov/press-release/20210909/fema-defines-equity-its-mission-making-programs-more-accessible.
 Section 14(g) of “Harris County Flood Control District 2018 Bond Order,” Harris County Flood Control District, June 12, 2018, https://www.hcfcd.org/Portals/62/Resilience/Bond-Program/bpl.pdf: 8.
 Neena Satija, Kiah Collier, and Al Shaw, “Houston officials let developers build homes inside reservoirs. But no one warned buyers”, Texas Tribune, October 12, 2017, https://apps.texastribune.org/harvey-reservoirs/.
 Lise Olsen, “Lawmaker calls for probe of what Corps knew of Harvey flooding risks,” Houston Chronicle, February 23, 2018, https://www.houstonchronicle.com/news/houston-texas/houston/article/Lawmaker-calls-for-probe-of-whether-Corps-knew-of-12705152.php.
 Inverse condemnation happens when a government, without paying suitable compensation, takes a property for public use that greatly damages the value of the plaintiff’s property: https://www.law.cornell.edu/wex/inverse_condemnation.
 In re Upstream Addicks & Barker (Tex.) Flood-Control Reservoirs, 146 Fed. Cl. 219 (2019).
 In re Upstream Addicks & Barker (Tex.) Flood-Control Reservoirs, 162 Fed. Cl. 495 (2022).
 Andrew Schneider, “Upstream Addicks and Barker Reservoir homeowners win $550,000 in damages in lawsuit over Harvey flooding,” Houston Public Media, November 2, 2022, https://www.houstonpublicmedia.org/articles/news/flooding/2022/11/02/436618/upstream-addicks-and-barker-reservoir-homeowners-win-550000-in-damages-in-lawsuit-over-harvey-flooding/.
 In re Upstream Addicks and Barker (Texas) Flood-Control Reservoirs, Brief for Fort Bend County; Willow Fork Drainage District; Cinco Mud Nos. 1, 6, 9, 12, & 14; Grand Lakes Mud Nos. 1, 2, & 4; and Houston Stronger, Document 498-1, filed April 18, 2022.
 U.S. Army Corps of Engineers, October 2020, Buffalo Bayou and Tributaries Resiliency Study, Texas: Review of Completed Projects Interim Feasibility Report, https://www.swg.usace.army.mil/Portals/26/BBTnT_Interim_Report_202001001_Final_1.pdf.
 Harris County Flood Control District, “Harris County Flood Control District and The U.S. Army Corps of Engineers Announce Path Forward for The Buffalo Bayou and Tributaries Resiliency Study,” press release, February 17, 2023, https://bit.ly/3OFXRJx.
 Harris County Flood Control District, Immediate Report – Final: Hurricane Harvey – Storm and Flood Information: 14, June 4, 2018, https://www.hcfcd.org/Portals/62/Harvey/immediate-flood-report-final-hurricane-harvey-2017.pdf.
 HCFCD, Immediate Report: Hurricane Harvey.
 HCFCD, Immediate Report: Hurricane Harvey.
 FEMA and HCFCD, Off the Charts: 14.
 FEMA and HCFCD, Off the Charts: 15.
 Lucio Vasquez, “The GLO discriminated against minorities in Houston and Harris County when denying federal flood relief, HUD says,” Houston Public Media, March 8, 2022, https://www.houstonpublicmedia.org/articles/news/politics/2022/03/08/420669/the-glo-discriminated-against-minorities-in-houston-and-harris-county-when-denying-federal-flood-relief-hud-says/.
 Andrew Schneider, “Harris County adopts plan to allocate $750 million in federal Harvey relief funds,” Houston Public Media, April 4, 2023, https://www.houstonpublicmedia.org/articles/news/harris-county/2023/04/04/448296/harris-county-adopts-plan-to-allocate-750-million-in-federal-harvey-relief-funds/.
 The Texas General Land Office, “Under Commissioner Buckingham’s New Plan, Houston and Harris County Achieving Success With Disaster Recovery and Mitigation Funding,” press release, June, 19, 2023, https://www.glo.texas.gov/the-glo/news/press-releases/2023/june/under-commissioner-buckinghams-new-plan-houston-and-harris-county-achieving-success-with-disaster-recovery-and-mitigation-funding.html.
 Jim Blackburn, Camille Chenevert, Jace Hodder, Sarah Swackhamer, Emily Fucile-Sanchez, and Luey Garcia, “A Proposal for Equitable Flooding Solutions in Northeast Houston,” prepared For Bayou City Initiative and Northeast Super Neighborhoods United, November 12, 2021, https://bit.ly/3QoKGxN.
 Harris County Flood Control District, “Flood Control District releases Phase 2 results of Tunnel Feasibility Study,” press release, June 21, 2022, https://www.hcfcd.org/Community/Press-Room?post=Flood+Control+District+releases++Phase+2+results+of+Tunnel+Feasibility+Study.
 Sabarethinam Kameshwar and Jamie E. Padgett, "Fragility Assessment of Above Ground Petroleum Storage Tanks under Storm Surge," July 2015, https://open.library.ubc.ca/media/stream/pdf/53032/1.0076134/1.
 Jim Blackburn, “Surge Flooding, Houston-Area Surge Flooding and Its Effects on Regional and National Security,” American Energy Society, https://energytoday.energysociety.org/surge-flooding---houston.html, accessed July 27, 2023.
 Mike Williams, “Failed storage tanks pose atmospheric risks during disasters, Rice study models how spilled chemicals likely spread during Ike, Harvey,” Rice University Office of Public Affairs, February 1, 2021, https://news.rice.edu/news/2021/failed-storage-tanks-pose-atmospheric-risks-during-disasters.
 Lisa Gray, “How Hurricane Laura's storm surge could have decimated Houston,” Houston Chronicle, August 28, 2020, https://www.houstonchronicle.com/projects/2020/storm-surge-houston/.
 John W. Ferguson, “Funding approved to study feasibility of storm-surge-blocking islands in Galveston Bay,” Houston Chronicle, January 20, 2023, https://www.houstonchronicle.com/news/houston-texas/environment/article/rice-galveston-bay-park-plan-study-17729842.php.
 A design storm is a hypothetical storm that a storm drainage or flood control system is designed to withstand: https://encyclopedia2.thefreedictionary.com/design+storm. Design storms are either based on historical precipitation data or rainfall characteristics in the project area or region: http://onlinemanuals.txdot.gov/txdotmanuals/hyd/hydrograph_method.htm.
 USACE and TGLO, Final Report: 1–17.
 USACE and TGLO, Final Report.
 Matt Dulin, “Urban flood buyouts are fracturing some Houston neighborhoods more than others,” Rice University Kinder Institute for Urban Research, July 12, 2021, https://kinder.rice.edu/urbanedge/urban-flood-buyouts-are-fracturing-some-houston-neighborhoods-more-others.
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