Texas Emergency Management ONLINE2010 Vol. 57 No. 1
UTCSR REVEALS THE “LAKE” THAT WASN’T THERE

When planning response to hurricanes and floods, an agency dedicated to “space research” would not immediately come to mind. But the University of Texas at Austin Center for Space Research has been a key partner of the Texas Division of Emergency Management since 1999.

Established in 1981, the research center is involved in everything from exploration of the solar system and the planet Mars to issues on Earth, including agriculture and fisheries, severe weather and oil spills.

Using images and information from satellites belonging to NASA, the National Oceanic and Atmospheric Agency (NOAA) and international space agencies, UTSCR has provided TDEM real-time information on events such as wildfires, tropical storms and the debris pattern that resulted from 2003 disintegration of the Space Shuttle Columbia. The Center also can provide computer generated images dramatically illustrating the impact of storm surge on Texas coastal cities from various categories of hurricanes, as well as digital maps of Texas showing where resources are staged and where evacuation buses and ambulances are traveling.

It was satellite imagery from UTCSR that revealed a “wild card” in flood diagnostics during Hurricane Alex. In addition to reservoirs overflowing on both sides of the border, a “lake” had sprung into existence as waters from the storm washed down from the mountains of Mexico. Natural contours of the terrain on the ground created a bottleneck on the Rio Salado in the states of Nuevo Leon and Tamaulipas.

“I discovered it in satellite imagery on Friday July 9, and reported it on a TDEM conference call. There’s a natural feature that constricts flow downstream along the Rio Salado once the floodplain is completely inundated,” said Dr. Gordon Wells, UTCSR program manager. Wells said the river course cuts across a ridgeline and into bedrock, trapping the water. The river backed up and spread across the landscape. “There was no ‘lake’ before the storm,” Wells explained.

Wells suspects the phenomenon might have occurred “sometime in past centuries before the Carranza Dam was constructed [in Mexico] in the late 1920s. But nothing appears in the observational record.” The broad, shallow lake revealed by satellite – and the geologic features that contributed to its sudden appearance – had been unknown to other U.S. and Mexican government agencies involved in monitoring and attempting to predict flood impact.

Wells said UTCSR works in several different areas of water research, including models of inland flows, plus satellite and aerial mapping for brush control and detection of invasive species along riverbanks and adjacent areas. The center’s research on water resources, dams and irrigation practices in Mexico within the Rio Grande basin was particularly useful during this year’s floods. “Our data complements what the National Weather Service provides through the West Gulf River Forecast Center,” Wells said.

“Floods occur across large areas where measurements are not made on the ground,” Wells said. “Satellite observations fill the gaps between the available surface measurements, and may be the only source of information for remote areas, such as the ungauged tributaries that originate in the mountains of Mexico. Radar satellites provide the most reliable coverage because they can image regions during the nighttime and daylight – even under heavy cloud cover.”

Hurricane Alex

NASA satellite image of Hurricane Alex on June 29. UTCSR captures information from NASA, NOAA and international satellites.
(Photo courtesy of NASA)