Flooding brings destruction, rejuvenation to state’s river systems.
Biblical amounts of water damage rivers, followed by crucial rebirth
Water and fire share the ability to almost simultaneously destroy and resurrect, a seemingly incongruous characteristic of these two opposing natural forces so rife with symbolism that the Bible makes good use of it. See: Genesis and Revelation. Or, in the case of water, look out the window of Stuart Marcus’ office.
“Most of the time when I look out my window, I see grassland sloping down to the river-bottom forest,” Marcus, manager of the Trinity River National Wildlife Refuge, said of the view from refuge headquarters near Liberty. “Now, all I see is water.”
The Trinity River is flooding and has been for weeks. Swelled by a wetter-than-normal spring that over the past three weeks has included record-setting rainfall and the resulting trillions of gallons of runoff, the Trinity, from its headwaters near the Oklahoma border to its terminus in Trinity Bay, has distended to many times its normal size, spilling over its banks and swallowing hundreds of thousands of acres of adjacent land.
It is much the same in other parts of Texas where portions of more than a dozen of the state’s major inland waterways are above flood stage with dozens of other waterways nearly so.
‘Necessary’ to function
That biblical amount of water has swept over the rivers’ natural floodplains and sometimes beyond, bringing with it destruction followed by rebirth.
“Floods in these riverbottom systems are akin to fires on prairies and uplands,” Marcus said. “They’re both incredibly destructive, but they replenish and rejuvenate, too. They are necessary for the systems to function.”
Periodic fires keep prairies and forests dynamic by setting back plant succession, returning minerals and other nutrients stored in burned plants to the soil and, in cases such as longleaf pine, creating the conditions necessary for some plants to survive.
The same is true for river-bottom forests and their associated wetlands. Floods sweep away accumulated debris clogging the forest floor, opening the understory and creating habitat for several plants and wildlife species that rely on such open terrain.
Flooding also is crucial to the life cycle of some riverine wildlife. Alligator gar, for example, spawn only in shallow, flooded terrestrial vegetation, their eggs attaching to the drowned land plants until they hatch.
Floodwaters also recharge oxbow lakes and swamps along the river, sweeping away clots of aquatic vegetation (often, invasive species such as water hyacinth and giant salvinia) that suffocate the shallow waters, as well as allowing fish and other aquatic animals to relocate and repopulate isolated oxbows and other wetlands.
Perhaps most crucial, nutrient-rich sediment deposited by floods recharge the soil in the floodplain, fueling what is one of the richest, most diverse ecosystems on the planet.
These positives are not without cost.
Almost the whole of the Trinity River National Wildlife Refuge has been closed to public use for the past month and likely will remain that way for at least another month as floodwaters from the refuge’s namesake waterway have inundated all but a handful of the refuge’s 25,000 acres.
“At least 95 percent and probably closer to 98 percent of refuge property is under water,” Marcus said of the federal refuge’s string of bottomland hardwood, swamp and upland forest tracts located along the lower Trinity. “I don’t see that changing for at least another three or four weeks or longer.”
The current flood is the most severe along the lower Trinity River since 1994. And while that 1994 flood saw even higher water levels than those experienced so far this year, the current flood is lasting much longer. Negative effects
“In 1994, the flooding lasted just two or three weeks,” Marcus said. “We’ve been flooded this time for a month, and it looks like this could last at least another month. There’s still a lot of water coming down the Trinity.”
Most of the refuge, created to protect and maintain remnants of the environmentally crucial bottomland hardwood forest, is undeveloped except for hiking trails, and damage to infrastructure there will be limited. But there are concerns at the refuge’s popular Champion Lake Unit, where water is pouring over the levee designed to create a shallow, 700-acre, cypress-studded reservoir.
The rushing water, pouring out of the flood-swelled lake and into the adjacent bottomland, almost certainly has damaged the levee, Marcus said.
“We won’t know how much it’s damaged until the water goes down,” Marcus said. “I’m just hoping it doesn’t completely wash it out and we lose the whole lake.”
The unusually high water has had negative effects on some wildlife in the flooded areas, forcing many animals — deer, small mammals such as raccoons and reptiles such as snakes and alligators — to abandon flooded areas and relocate to higher ground. Some have drowned. And even the higher ground doesn’t guarantee safety. Much loss, tragedy
“You’ve got deer and other wildlife being pushed up onto roads where they get hit by cars,” Marcus said.
Some wildlife wasn’t able to even attempt escaping rising floodwater. The Trinity River refuge holds several rookeries of colonial-nesting wading birds such as herons and egrets, with the birds building communal nurseries among the limbs of clusters of trees growing in shallow wetlands. As water rose as much as 1520 feet or more, it inundated lower nests, many of which held eggs or young birds, Marcus said.
Similar events are playing out in floodplains across much of Texas. Among the waterways with water levels above flood level are all or part of the Red, Sulphur, Trinity, Neches, Nueces, Colorado, Brazos, Sabine, Navidad, Navasota and Guadalupe rivers, with flooding conditions on some of them expected to continue for weeks.
“There’s certainly not anything good about this for the people impacted by all this flooding, and my heart goes out to them. There’s a lot of loss and tragedy associated with floods like this,” Marcus said.
But there will be benefits to the natural systems along these rivers, even if they are awfully hard to see under all that water.