Flood Risk in Houston, TX

An article in the Houston Chronicle by Vanessa Brashier dated February 25, 2018 provides a case study for how a prospective property buyer could perform an initial evaluation of flooding risk.  The article is entitled "Liberty County community signals growth is ahead - Encino Estates offers country living and affordability north of Dayton." https://www.houstonchronicle.com/business/real-estate/article/Liberty-County-community-signals-growth-is-ahead-12705439.php To begin the evaluation the prospective property buyer could easily perform two key steps from their home computer as follows: Step 1:  Locate property using Google Maps. In this example I entered the search term "maps encino estates liberty county, tx" and then clicked on the Directions tab on the featured listing as shown below.    The resulting map is shown in Figure 1. Encino Estates is a new development, so the actual area of the subdivision does not show up on the Streets map....

A recent Houston Chronicle article was re-printed in the February 14, 2018 edition of the Bay Area Citizen newspaper.  It was entitled "Major routes through Houston need to be "flood-proofed" to keep freight flowing." The original article can be viewed at the link below: https://www.houstonchronicle.com/news/transportation/article/Ed-Emmett-lays-out-case-to-flood-proof-freeways-12558864.php?cmpid=gsa-chron-result In the article Harris County Judge Ed Emmett encouraged Texas House Transportation Committee members to empower state transportation officials to "flood proof" some major routes so freight can keep flowing into, and through, the region during severe storms. Flooded roads during storms are a well-known problem in the Houston area.  Residents can be caught in dangerous situations due to the rising water and may be blocked from evacuating to safer locations. The Chronicle article mentions that all major freeways in every directio...

The summary of Harvey damage to properties provided by the City of Friendswood available for review on ArcGIS Online provides a rare opportunity for examination of actual flooding and assessment of the accuracy of the floodplain mapping. The occurrence of significant damage outside of any floodplain can indicate that the maps are not accurate or other factors not accounted for in the FEMA methodology were in effect. The floodplains included on the FEMA Flood Insurance Rate Maps (FIRM) are produced by modeling rainfall amount and intensity, drainage capacity and rate, and the topography.  The topography is the primary factor governing the configuration of a mapped floodplain and it is not subject to variation based on input assumptions. The Friendswood example shows that consideration of the detailed topography along with the floodplain maps can provide a better prediction of where flood damage is likely to occur than use of the FIRM alone. Map #1 shows the portion ...

Hurricane Harvey caused widespread damage in Friendswood, a city that straddles the boundary between Harris and Galveston counties about 20 miles southeast of downtown Houston. Friendswood was featured in a February 4, 2018 Houston Chronicle article entitled "After Harvey's floods, Friendswood will allow residents to build at ground level - Effort helps 300 homeowners but puts other at risk." https://www.houstonchronicle.com/news/houston-texas/houston/article/After-Harvey-s-floods-Houston-area-city-will-12540769.php?cmpid=gsa-chron-result The main point of the article is that city officials decided to use an older version of the Flood Insurance Rate Maps (FIRM) to define the Special Flood Hazard Areas (SFHA) where regulations for repair and new construction are in effect.  The older maps are from 1999 and have smaller SFHAs compared to the current (2006) maps. That decision raises many issues that will be discussed in future blog posts.  In addition to pr...

An article in the Sunday February 11th edition of the Houston Chronicle presented many issues related to proposed flood mitigation projects.  The article is entitled "Flooding battle plans take shape - Six months after Harvey, local, state leaders eye an overhaul of defenses." https://www.houstonchronicle.com/news/houston-texas/houston/article/Nearly-six-months-after-Harvey-some-traction-for-12567647.php?cmpid=gsa-chron-result Discussed in the article were many proposals that have been in the news in recent months, including: Increased buyouts of flood-prone properties Additions of and improvements for bayous, dams, and reservoirs New, tougher regulations governing development in floodplains Recalculation of methods for measuring rainfall and defining the 100-year storm Drawing of new floodplain maps using the updated rainfall estimates An interesting quote from Houston mayor Sylvester Turner caught my attention since one of the main themes of this blog is ...

On a recent trip to League City I visited the Ghirardi WaterSmart Park. It is located along Louisiana Avenue just south of FM 518.  The park is built around a few very old live oak trees that have been preserved.  It also has a play structure for the kids. The park is designed to educate the public about various methods to mitigate runoff, conserve water, improve water quality, and protect natural habitats.  Many of the techniques on display could be  easily adopted by neighborhoods and individual homeowners.   The use of pervious pavers on driveways and sidewalks would slow runoff by allowing water to soak into the ground.  The pavers also act as filters for oil and heavy metal particles leaking from cars. Rain gardens can be installed to collect, absorb, and filter storm water.  Rain gardens are bowl-shaped depressions containing various plants and ground cover materials such as mulch.  These act to slow the flow of wat...

An article in the Galveston Daily News by Marissa Barnett dated January 30, 2018 was entitled "Residents, officials, discuss county drainage woes" . It discussed a meeting held on January 29 where Galveston County residents and officials met to "open conversations about what should be done to alleviate flooding, including ideas about elevating bridges and widening ditches." There were some particularly interesting statements mentioned in the article.  One was that some residents claimed that the FM 517 overpass bridge and other bridges along I-45 likely worsened flooding during Harvey by acting as dams.  Debris stacked up under the bridges or got caught in pilings, keeping water from flowing through.  A resident of a canal home in Clear Creek Village (located in League City along Clear Creek) claimed that development upstream caused issues downstream in area bayous.  There was no mention of whether or not data supporting these claims was presented. The mayo...