Advanced science.  Applied technology.


Underwater cave-mapping sensor wins technology award

July 21, 2010 — Sensor technology developed to remotely characterize the path, dimensions and morphology of caves and other underground conduits and cavities has received a 2010 R&D 100 Award. R&D Magazine selected Southwest Research Institute's® (SwRI®) remote neutrally buoyant sensors as one of the 100 most significant technological achievements of the past year. 

The sensors are designed to float through an underground cave or conduit and measure the path, dimensions and morphology of the void using an array of ultrasound sensors. Information gathered during travel is collected by retrieving the floating sensor and physically transferring the data or by remotely transferring the data to a static sensor tethered to the ground as the sensor floats past it. 

"The information captured from these sensors is critically important for water-resource management and geotechnical risk assessment," said Dr. Ronald Green, Institute scientist in the Geosciences and Engineering Division at SwRI and a principal developer of the sensor. "Adequate management of karst aquifers requires knowledge of water flow through caves and conduits, including location, size and morphology of the complex interconnected voids. The technology also is applicable to assessing geotechnical risks from karst features, such as caves, that are encountered when karst features are located near dams or when roads and buildings are constructed over unknown and uncharacterized cave and karst features." 

The sensor technology provides a unique capability to acquire data that can otherwise only be obtained by divers physically mapping caves or by injecting dye to determine the path and travel time of water flow through caves or other underground cavities and voids. Cave diving is an extremely dangerous endeavor and is limited to large passageways, relatively shallow caves and limited distances. Information provided by dye tracer tests is limited to identifying the point of discharge for each injection and the time of travel.

"Remote neutrally buoyant sensors are built with off-the-shelf components and therefore are relatively inexpensive," added Ben Abbott, Institute engineer in the Automation and Data Systems Division at SwRI and a principal developer of the sensor. "Because of this, many can be deployed and the survey would be successful if information is retrieved from only one sensor at the conclusion of its travel." Because of their low cost, the sensors can be deployed cost-effectively into challenging environments because the loss of a sensor or even several sensors is not cost-prohibitive. 

This technology can be used to map other partially or fully water-filled passageways. Examples of other applications include pipelines, particularly those with small diameter or interior dimensions restricted by sediment deposition or corrosion, and sanitary sewers, particularly in older cities where accurate maps and records are not available and the condition of the sewer system precludes safe human access. Another potential application is geotechnical settings such as flooded underground mines, tunnels or conduits that are not safe for manned entry. 

SwRI has won 35 R&D 100 Awards since 1971. This year's awards will be presented Nov. 11, 2010, in Orlando. 

View the Neutrally Bouyant Sensors Video.

For more information contact Deb Schmid, +1 210 522 2254, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.