When the floodwaters drained from Riverside Park in the days after Hurricane Harvey, lots of soil went with them, taking large chunks from the bank of the Guadalupe River.
Harvey laid bare questions about how well Victoria’s buildings and water system could withstand natural disasters. But one other huge impact of the storm was erosion. Now, almost two years after the storm, the city is preparing to use about $1.8 million in federal funding, plus a $180,000 match, to address the sections of the riverbank with the most noticeable, and the most dangerous, erosion after Harvey.
One area of erosion is along the bank near the city’s raw water pump station, which is where the city draws water from the river before it’s treated. The second area is in Riverside Park, near the roadway and the park’s duck pond.
“If this keeps going, what’s going to happen? The sidewalk’s gone, the road will be gone, and eventually it would get into the duck pond,” said Colby VanGundy, the director of Victoria’s parks department. “If we don’t do something now, we’re just going to kick the can down the curb and have to do something later.”
With the funding from the Emergency Watershed Protection Program, the city has hired Tom Hegemier to figure out why these portions of the Guadalupe River are more susceptible to erosion and how to prevent it in the future. Hegemier, who works for the engineering firm Doucet and Associates, is leading a team that will figure out how to fix the most severely eroded parts of the riverbank in one 600-foot stretch near the pump station and another 600-foot stretch in Riverside Park.
Hegemier said his team will study both sites to figure out what native materials, such as rocks, boulders, vegetation and trees, would be able to stabilize the riverbank best.
Hegemier’s work also will try to answer the question of why these two stretches of riverbank are more prone to erosion than others and gauge how the river’s banks have shifted throughout history using images from drones and satellites. The team will also try to figure out how the floodwaters that covered most of the Riverside Golf Course drained back into the river and whether they flowed down a path that was directly over the eroded areas of the bank.
“We want to know why it’s happening at those two locations and, definitely, maybe how much water is going in those directions and design accordingly,” Hegemier said.
Erosion along the Guadalupe River was also an issue after the record-breaking floods in 1998, which eroded some of the same areas Harvey did. Victoria used soil protection blankets, which look a bit like netting, to hold in the soil. That anti-erosion plan worked until Hurricane Harvey. Hegemier said he expected to opt for more natural anti-erosion installations, instead of a concrete wall or netting, because they’d likely be better able to adapt to the quirks of a river.
“It’s a very dynamic environment,” he said. “River environments change a lot with each flood, so rocks and boulders shift and move, while any kind of big concrete structure is rigid.”
Other cities in Texas are also working on projects to address erosion from Harvey’s floodwaters. Gonzales is working on a smaller project to address an area where a large portion of land slid into the river in the city’s Independence Park, Hegemier said.
Asmeret Asefaw Berhe, an associate professor at the University of California, Merced, said addressing major erosion issues is critical for communities because erosion causes both ecologic and economic impacts. Besides just eating away at a riverbank or shoreline, erosion during natural disasters like hurricanes can bring sediments and other contaminants into the water supply, which can have residual impacts on fishing and boating industries and a community’s drinking water supply. Berhe said addressing erosion concerns quickly by replacing both lost soil and lost vegetation that’s uprooted during a storm is critical to the long-term survival of coastal areas.
“Limiting erosion is really key in communities that are vulnerable to big climate events like hurricanes, which we know are going to happen with increasing regularity because of climate change,” she said.
Hegemier said his team is still in the planning phases and that designs to address erosion haven’t yet been finalized. City engineer Ken Gill estimated the project would be done at the end of this year or early in 2020.