[On October 25, 2017 Harris County Judge Ed Emmett released a list of post-Harvey recommendations relating to flooding. This document presents those recommendations in bold text followed by responses and suggestions in regular text. The responses reflect the views of the author. They don’t necessarily reflect the views of his employer or any of the organizations with which he volunteers.]
Harvey was the worst flood in our history, but Harvey was not a singular event. It followed two other major rain events in recent years. This area has seen three of these so-called 500-year rains in the past two years. Either our definition of a 500-year rain needs updating or we can hope that we are safe for the next 1,500 years.
This illustrates how civil engineers and meteorologists have failed to adequately communicate the likelihood of large amounts of rainfall (inches in a certain period of time) to the public and to our elected officials. This lack of effective risk communication not only leads to misconceptions about rainfall probabilities, it also leads to misconceptions about the likelihood of high bayou flowrates and flood stages occurring (resulting from rainfall runoff). It also leads to misconceptions about what depth of rain our infrastructure is designed to handle over a certain time period.
To clarify, a 100-year storm has a 1 in 100 chance of occurring every year. That’s a 1% chance of occurrence during a 1 year time period. In the Harris County region a 100-year storm is about 13 inches of rain in 24 hours. Over a 30 year mortgage there is a 26% chance of that size rain event occurring. Over a 50 year period there is a 40% chance of occurrence. Over a 100 year period there is a 63% chance of occurrence. The likelihood of this size rain event occurring approaches 100% as the time period hits 900 or 1,000 years. The longer the time period the higher the likelihood. The graph below illustrates how the likelihood increases with time. The red line is the 100-year event for the southeastern part of Harris County.
Policy makers across the United States selected the 1% annual chance event as the design basis for drainage infrastructure in second half of the 20th century – sometime between 1960 to 1990, depending on the location. This policy decision strikes a balance between benefit and cost. As we enhance drainage system designs to achieve lower risk levels — the desired BENEFITS; the associated COSTS of these systems go up. This is because lower risk levels require bigger, deeper, and wider channels; bigger pipes; larger inlets; bigger dams; and higher structure elevations.
In the immediate aftermath of Harvey people appear willing to pay almost any amount of money to achieve risk reduction benefits. How much are we willing to pay to reduce the risk of flooding any particular structure from 1.0% a year to 0.2% a year? The risk reduction price tag (upfront costs plus operational costs and debt financing) must be compared to the avoided damage costs times their probability of occurring.
Following Harvey, government officials, academics, private institutions and the general public have all weighed in with ideas of what our area needs to do to protect life and property from future floods.
We should not frame post-Harvey decision-making as binary choices: protect life and property or not protect life and property. This is choice of what level of risk we are willing to accept. The choice should be framed as “pay $X for Y 30-year cumulative risk level, which equals an annualized cost of $Z of avoided damages and additional benefits” or “pay $A for B 30-year cumulative risk level, which equals an annualized cost of $C of avoided damages and additional benefits.” We should assertively pursue projects with a favorable benefit to cost ratio.
(1) Create a regional flood control/water management organization similar to the Transportation Policy Council at the Houston-Galveston Area Council. This will allow for multi-county coordination of flood control and water management.
–
This already exists. It is called the Regional Flood Management Council. Information about this body is on the Houston-Galveston Area Council webpage: http://www.h-gac.com/board-of-directors/advisory-committees/regional-flood-management-council/default.aspx Perhaps the H-GAC board of directors and the member governments need to update its charge, duties, and authorities?–
(2) FEMA flood plain maps need to be revised immediately to reflect the impact of Harvey. Development rules should focus on restricting development in the 500-year flood plain instead of the 100-year flood plain — or the 100 year flood plain needs to be vastly redefined and updated.
Floodplain maps definitely should be updated, but the update should only occur after the National Weather Service rainfall statistics study called Atlas 14 is completed in May 2018. Updating development regulations should be considered, but it would be prudent for all stakeholders to recognize the benefits (the value of avoided future damages times the likelihood of the loss) and the costs.
(3) A third reservoir should be built to protect the west and northwest sections of Harris County. Rather than waiting on federal funds, the reservoir should be funded by the State of Texas’ “rainy day fund.” The reservoir should be part of a larger project to create a state or national park for the Katy Prairie.
Consideration of a third reservoir is a worthy effort, however, the benefits and costs as outlined above, should be determined prior to moving forward. All stakeholders need to fully understand that a new reservoir will not “protect” the west and northwest sections of the county. It WILL reduce the risk of flooding for some, increase the risk of flooding for others, and will cost a substantial amount of money. If the cumulative benefits (include recreational value, aesthetics, and flood risk reduction) are greater than the costs (capital and operations) than let’s do it!
(4) The U.S. Army Corps of Engineers should immediately fund the four Harris County Flood Control District projects that are now ready for completion. Those four are Brays Bayou, White Oak Bayou, Hunting Bayou and Clear Creek. New flood maps showing the impact of these projects should be released so homeowners will know if their property will remain flood prone.
This is a no-brainer. Let’s do this.
(5) Old watersheds in developed areas in Harris County should be identified. For example, those areas downstream from Addicks Reservoir need to know where an “uncontrolled release” over the spillway would flow.
This is a worthy effort and it could be reasonably accomplished using historic aerial photographs. It might help in planning efforts and in floodplain modeling efforts to some extent.
(6) The Harris County Office of Emergency Management, working with municipalities and special districts, should develop a state-of-the-art flood warning system and localized evacuation plans. Such plans should use recognized volunteer organizations to assist first responders. The Harris County Sheriff’s Office and the Community Emergency Response Teams should have a defined water rescue effort featuring private boats and high-water vehicles.
A new or enhanced flood warning system should be designed like an Amber alert to cell phones and should be implemented using an “op-out” approach. Some areas of the county and city with a low percentage of residents with cell phones should deploy public sirens or alarms to warn those areas without ubiquitous cell phone use.
(7) Lake Houston and Lake Conroe should be converted to serve as Flood Control facilities in addition to serving as water supplies. Lake Houston should be restored to maximum storage capacity, and the San Jacinto River Authority should create retention/detention capacity upstream of Lake Houston. And the San Jacinto River Authority should have representation from Harris County.
These proposals should also be evaluated using a robust benefit / cost analysis. The analysis should consider all costs, including construction costs, right of way acquisition costs (for a large amount of the privately only land around both lakes might be required), dam and gate modifications, dredging costs, dredge spoil disposal costs, design and permitting costs, operational costs, and the value of lost drinking water. These costs should be compared to the monetized risk reduction benefit of fewer homes, of a certain value, flooding less often. These proposed projects don’t appear, at first glance, to have a favorable benefit / cost ratio.It would seem fair and appropriate for Harris County to appoint a board member to serve on the SJRA Board.
(8) The Harris County Emergency Operations Center should be expanded to assist emergency operations for smaller surrounding counties.
Yes.
(9) The roles and responsibilities of municipal utility districts and other special districts should be clarified to include flood control and storm water management, in cooperation with the Harris County Flood Control District. Existing districts should be studied for untapped capacity, and new districts developed with flood control in mind. Until a true 100-year flood level is defined, the 500-year level should be used for detention purposes.
Clarification of the purpose of local government entities is prudent. Harris County Flood Control District evaluates bayous and watersheds for opportunities to add detention facilities and to otherwise reduce flood risks. If they see opportunities they often work with land owners and MUDs to build new facilities and reduce flood risks. The use of the 500-year storm should be considered as discussed in Item 2 above.
(10) All underpasses that have the potential for drowning should be identified and equipped with automatic barriers or be part of a comprehensive manual plan for closures. In addition, vehicle manufacturers should be encouraged to develop technology to detect high water.
Yes, this should definitely be implemented. It will probably save more lives than most of the other suggestions on this list (except the Amber-alert flood warning system, which will likely save many lives during an evacuation from a hurricane storm surge).
(11) The Harris County Flood Control District should develop comprehensive plans for every major watershed in Harris County, with immediate attention given to the entire length of Buffalo Bayou and to plans to divert storm water around downtown Houston, either through a canal or tunnel system.
These projects are worthy of investigation using the benefit / cost ratio approach previously outlined.
(12) Federal, state and local governments should implement a buyout and/or elevation program for all homes located in the 100-year flood plain or that have flooded repeatedly. Such a buyout/elevation program should use traditional government funding and private funding, such as social impact bonds.
This is great suggestion that typically has a very good benefit to cost ratio, especially if the buyouts are contiguous and flood damage reduction detention or conveyance can be constructed in the area after the buyouts are completed.
(13) The State of Texas should institute clear rules for approval of development plats in unincorporated areas, specifically those areas in the extraterritorial jurisdiction of a city. Additionally, there should be clear requirements for disclosure of flood risk to homebuyers and renters.
The Texas Legislature should grant counties additional development and floodplain regulatory powers and clarify how county and city rules should be applied in the extraterritorial jurisdictions. I strongly support a statewide law mandating flood risk disclosure in a real estate transaction (buying, renting, or leasing) involving an individual or family. This disclosure should provide the risk of flooding over durations of 1, 30, and 50 years for all properties – not just those located in the 100-year regulatory floodplain. Since the risk of flooding outside the 100-year regulatory floodplain is less than 1% annually but is NOT zero, the disclosure must include a statement indicating that the risk of flooding is less than 1% per year or less than 26% over 30 years for those homes.
(14) The U.S. Army Corps of Engineers should restore the dams and detention areas of Addicks and Barker reservoirs to first-class condition including, if necessary, removing dirt and vegetation within the reservoirs.
The gate and berm repair project should be completed as quickly as possible. Removing dirt and vegetation within the reservoirs should be evaluated using the benefit / cost ratio approach outlined earlier in this document.
(15) Given the population of unincorporated Harris County and the restrictions on incorporation and annexation, Harris County should be allowed some ordinance making power and should receive a portion of the sales tax collected in unincorporated areas. To continue to exclusively rely on the property tax is fundamentally unfair and unsustainable.
I support additional rule-making authority for the county to help with development and floodplain management issues.