UNM Researchers Collaborate on Flood Control and River Restoration Projects

February 27, 2008

Every time there’s a hard rain on Albuquerque’s west side, tons of dirt and rock wash down the Calabacillas Arroyo and into the Rio Grande. The sediment deposits narrow the 600-foot river bed down to 300 feet and force water to flow harder and faster through the river – a change in flow that interests the U.S. Army Corps of Engineers.

Photo: Research Scientist Christian LeJeune (in cap) demonstrates ground water sampling.

The Corps of Engineers is responsible for flood control on the river, and it also has the job of restoring the vegetation in wooded areas along the banks. Sometimes the two jobs collide, so the Corps of Engineers has turned to the University of New Mexico to find answers. Associate Professor of Civil Engineering Julie Coonrod oversees five contracts for research on a variety of projects.

The Corps of Engineers is currently looking for scientific guidance about how to design projects that encourage native vegetation, control erosion and direct flood waters in a beneficial way. In research terms, that means breaking up the complex question into specific projects.

Monitoring for Erosion
Civil Engineering Professors John Stormont, Coonrod and Earth and Planetary Sciences LiDAR lab director Tim Wawrzyniec along with Research Scientist and recent UNM graduate Jed Frechette are working on a project to monitor bank erosion. They use erosion pins and LiDAR scanning to collect data on the geometry of the banks. The information will be used to predict what will happen to the banks under various conditions, such as the removal of some non-native plant species.

Evaporation and Restoration in the Bosque
Biology Professor Cliff Dahm, is leading the project to map the amount of water released into the air from the plants along the river, a process called evapotranspiration. Biology Research Scientist Jim Thibault and Research Assistant Professors James Cleverly and Kristin Vanderbilt work with Dahm, maintaining databases containing daily evapotranspiration and water table measurements.

As part of the project they are exploring how a wildfire in June 2006 affected the evapotranspiration rates and water table in the Albuquerque area. A separate part of the project also measures evaporative losses from sand in both wet and dry conditions.

Monitoring Sediment
If you drive over the Alameda Bridge in Albuquerque, you can watch sediment build into small islands just upstream of the new diversion dam. The dam was installed to draw water from the river and treat it to be used as drinking water. If you watch over time, you can see the sediment islands build up and wash away as the operators of the collapsible dam carefully manipulate it to move the sediment build-ups down river.

Department of Earth and Planetary Sciences Associate Professor Grant Meyer and Ph.D. student Ben Swanson are documenting the way the sediment moves down the Rio Grande with aerial photography. They are looking at photos from 1985 through 2006 and graphing ways the river responded to both natural and man-made changes as it flowed through Albuquerque.

This piece of the puzzle will provide information about how sediment affects the efforts to restore the natural flood plain. They are also doing a similar analysis on the Chama River, a simpler system with fewer of the variables that make the Rio Grande so difficult to study.

Ground Water/Surface Water Interaction
Biology Research Professor Emeritus Clifford Crawford established the Bosque Ecosystem Monitoring Program in the Rio Grande Bosque in the 1980s. The long-term project monitors ground water near the river in the bosque through the central Rio Grande valley.

A project involving Crawford, Stormont and Coonrod along with Research Scientist Christian Le Jeune is measuring ground water levels. Graduate student Isaiah Pedro completed detailed soils analyses near each well.

The project also evaluates the health of the riparian ecology in the vicinity of the new Albuquerque/Bernalillo Water Authority Dam in Albuquerque’s North Valley. The Water Authority will soon begin diverting water from the river into a treatment system and graduate student Kelly Isaacson is working on a computerized terrain model tying river flow and ground water depths together.

“We’re working on some visualization tools that show how the flow rate in the river controls the depth of the river in that reach, and how that controls the depth of the groundwater,” says Coonrod. The project will continue after the regular diversions begin and they will be able to determine what impact the water diversion is having on ground water and the riparian forest ecology in the vicinity of the dam.

All the projects provide information that will be used to update and refine models that analyze the way the Rio Grande changes as the seasons, and human impacts alter the way the water flows through the Albuquerque reach of the river.

The models can be used by various state and federal agencies as they prepare flood and restoration projects. Currently 11 faculty members from three departments and a number of graduate students are working on the projects. Their work will continue into 2009.