The Brazos River has seen record high river crest elevations from torrential rain events since 2016, creating a sense of urgency when it comes to the rate at which the river is eroding dry land in its path.

Officials with the city of Sugar Land are conducting a study to develop a proactive approach for addressing the erosion. This will help to gain more knowledge regarding the river's geomorphology—or the study of the characteristics, origin and development of landforms—and discuss future projected movement with stakeholders, Assistant City Manager Chris Steubing said during an April 3 presentation to City Council.

"We're dealing with it head-on, and we've got a great team assembled," Steubing said. "[The erosion] is not consistent. It's hard to predict. What we are working on now is the ability to provide some type of probability and an association of how do you look at that related to infrastructure."

From the study, city officials have identified eight critical locations along the 9-mile span of the river through Sugar Land to perform the erosion assessment, Senior Engineer Jorge Alba said. These locations include the river bend near New Territory and Greatwood; a portion along Sugar Land Memorial Park; and a portion south of University Boulevard, Alba said.

"We have held meetings and workshops with Texas A&M [University] to evaluate the work that we have completed to date," Alba said. "We have developed future work associated with the probability, risk and consequences. We are working right now in selecting the analysis methodology, and we defined the areas where we are going to conduct geotechnical investigation and testing to validate our methodology."

In 2011, city officials developed an Emergency Action Plan in coordination with levee improvement districts and Fort Bend County to address flooding events. In June 2015, the Brazos River gauge in Richmond reached 49.73 feet with local rainfall of 11 inches in eight hours, Steubing said.

In June 2016, the river reached a record high of 54.73 feet. However, most of the rain made landfall northwest of Fort Bend County in Washington County and made its way southeast via the Brazos River, Steubing said. In 2017, during Hurricane Harvey, the river reached a record high again at 55.19 feet, receiving 32-35 inches over a span of about three days, he said.

Going forward, the city, in association with Houston-based design firm Huitt-Zollars and Texas A&M University, will continue to perform geotechnical testing of soil samples to determine erosion rates. Officials will also analyze the erosion to determine the critical velocities at the river bank as well as the probability, risk and consequences of bank failure.

There are several possible solutions to the erosion, including building rock weirs—horizontal barriers across the width of the river—sheet-piling, or building a foundation out of riprap, or loose stone. Once the risks and consequences have been identified, it will be easier to determine the best way to mediate the erosion, said Greg Wine, public works leader for Huitt-Zollars.

"Mother nature would move [the river], and we built levees, we have bridges, we have parks, and now we'd like to keep things the way we think they're supposed to be," Wine said. "Unfortunately, mother nature is still doing what it's done since the beginning of time, so that's the dilemma that we're in today."

A stakeholder workshop with Fort Bend County LIDs, the Texas Department of Transportation and other stakeholders will be held in April or May, and the engineering department will issue a final report with a recommendation in May or June, bringing forth another City Council workshop by June, Steubing said.