MERCEDES — Water. It’s an abundant resource that impacts everything we do and with which we are all intimately familiar. But, just how much do we really know about the waters that surround our communities?
Thanks to the emergence of new water sensor technologies, scientists at the U.S. Geological Survey are learning there’s more nuance to the streams, rivers, aquifers and other bodies of water around us. These new tools not only give officials new insights on flooding and water quality in near real time, but they also allow researchers to track patterns and trends for particular bodies of water.
One such USGS researcher, Dr. Doug Schnoebelen, explained how these new technologies are already making an impact on flood prevention and water resource management during a meeting at the International Boundary and Water Commission Field Offices in Mercedes last Wednesday.
“These are new tools to help us monitor different parameters for water quality in near real time, every 15 minute increments,” Schnoebelen said after the meeting. “We can start to see trends and if the water is getting better or worse.”
Known for the flood gauges seen at streams and rivers around the country, which measure the height of floodwaters during storm events, the USGS has taken things high tech, Schnoebelen explained.
Newer generations of flood gauges employ satellite technology, which can take measurements and relay flood conditions online in 15-minute intervals.
“We’re trying to shorten that window down even further,” Schnoebelen said.
“In my career, I remember when we would shoot it every eight hours and four hours, and we thought four hours was great.”
There are also various sensors that can be mounted on drones to measure floodwater velocity, depth and volume. Researchers use Doppler radar to collect data, thermal imagery, hyperspectral imagery and others, Schnoebelen said.
The wealth of data helps scientists and emergency management officials answer three vital questions during flood events: what areas will flood, how deep will floodwaters get, and when will a flood arrive?
Schnoebelen, who has studied inundation and flood control throughout the Midwest along the Mississippi River, said it was a Texas flood which sparked a concerted interest in developing these new technologies.
In 2015, a catastrophic flash flood struck Wimberley, located just a few miles northwest of San Marcos, when the Blanco River overtopped its banks after the area was inundated with over a dozen inches of rain in just a few hours.
With no flood gauges located upstream, the town had no warning as a 40-foot wall of water crashed into the community and killed 13 people.
“(It was) literally what I call a rain bomb that went off there in the Hill Country. It was a wall of water that came down through there,” Schnoebelen said.
After that, Gov. Greg Abbott, along with the Texas Water Development Board, approved funding for the installation of the high tech sensor equipment in the area.
Then, when Hurricane Harvey dumped more than 50 inches of rain over Houston in 2017, the U.S. Army Corps of Engineers called on Schnoebelen and his team to help them as the Barker Reservoir overflowed uncontrollably.
“We were able to get these cameras out there. We took some imagery … and quickly got them some information there on the velocities and how much water was going through,” he said.
The data Schnoebelen collects during flood events isn’t just useful at the time of an event. That data, along with data collected during fair weather, allows researchers to create detailed models that show how and where a particular location will flood.
“We do modeling, we take some geospatial processing, marry all this together and then we put that on our flood inundation … web mapping application,” he said, adding that the models are available to the public online.
He likened the images that result from the combining of multiple datasets to an atlas — one emergency management officials can use to plan ahead for things such as road closures.
“It’s just like a picture book, if you will, of flood depth. Every 5 feet, 10 feet, we can show how far that flood is going to go,” he said. The images also show how deep an area will flood — whether by a few inches or a few feet.
While knowing how flood waters will behave is important, understanding the condition of a body of water during non-flood times can allow for better management of a vital resource.
“The basic question we all want to answer is, ‘Is our water getting better or worse?’ And this gives us a tool to look at that in near real time,” Schnoebelen said of another newer technology currently being deployed on the Arroyo Colorado just outside of Rio Hondo.
There, from beneath the iconic Rio Hondo lift bridge, hangs a metal cylinder just a couple of feet in length. Inside, numerous sensors can measure everything from the water’s temperature, to salinity, pH, oxygen content, chlorophyll content, dissolved organic carbons and more.
USGS installed the sensor, or sonde, via funding from the Texas Commission on Environmental Quality, which wanted more precise data on the waterway. The arroyo serves as the primary outflow to the Laguna Madre for runoff from the majority of the Rio Grande Valley.
The waterway is further unique in that it is affected by tidal fluctuations, which alternately make the water more or less brackish.
The sonde, which Schnoebelen called a “lab on a stick,” is so sensitive, it not only detects those tidal fluctuations, but also how the profile of the water changes after a rain, or when a barge passes by — not just at the surface, but at various depths throughout the water column, he said.
“It’s a real game changer looking at, not only the groundwater, but river systems, as well,” he said.
Schnoebelen hopes the combination of these new sensors and monitoring techniques will give people a better understanding of their water resources by allowing researchers to create an integrated “systems approach” to water monitoring.
“You can’t manage what you can’t monitor,” he said.
The USGS works via what Schnoebelen called a “reimbursable model.” Its scientists partner with other agencies to install sensors where communities feel they are needed. Currently, there are few sites in the Valley with USGS water quality or flood gauge sensors, but it’s something Schnoebelen hopes to improve upon.
“I would like to get more stream gauges and more sensors down here, absolutely,” he said.
All it takes to get things started is an invitation. “We’re happy to meet with anybody to start the conversation,” he said.