Robots and Artificial Reefs for Water Conservation and Management

Randy Price, Smith, Daniel, Hall, Steven G.  |  9/15/2015 8:30:21 PM

Steven G. Hall, Daniel Smith, Randy R. Price, Melody Thomas and Jeanne Steyer

Bioenvironmental and aquacultural engineers are using smart and biological solutions to address water quality issues in rivers, lakes, ponds and coastal areas. Autonomous vehicles can help assess and enhance water quality, while bioengineered solutions such as artificial reefs may contribute to enhanced coastal protection as well as improved water quality.

Water quantity and quality are critical issues in Louisiana and around the world. Severe water shortages may be one of the most critical issues of the 21st century. In Louisiana, water quantity has not become an extreme problem yet, but water quality is already of significant concern. Smarter ways of approaching freshwater quality in streams, lakes and bayous include use of intelligent buffer strips, wise management of agricultural and industrial wastes, sustainable practices of ecological management. In the coastal zone, including salt and estuarine environments, engineered solutions that enhance local ecosystems, improve water quality and provide coastal protection are needed.

Being water-wise means using smart technologies. Some, like the robotic boats, are actually smart, in that they use microprocessors and programming to address certain water-related issues. Others, like the artificial reefs, are smart to use because they, while seeming simple, use resources wisely.

Smart Solutions: Robotic Boats
One LSU AgCenter invention, patented in 2006 and licensed in 2013, is a robotic boat originally targeted at reducing predatory birds on aquaculture ponds. The dual pontoon, dual paddlewheel automated boats are powered by the sun, microcontroller driven and may have a variety of sensors including GPS and water quality sensors. The boats were effective at reducing predatory birds and have been developed further in recent years. Additional capabilities include communication and cooperation among boats in a fleet to address water quality issues. A second use relates to measuring effects of restoration projects, which may enhance water quality, for example in the coastal zone.

Water Quality Testing
Water quality is important in natural and managed water bodies to protect wildlife and serve as a source for irrigation and drinking water. Parameters of interest include dissolved oxygen, temperature, nutrients such as nitrogen, total suspended solids and pollutants such as heavy metals or organic pesticides. By mounting water quality measurement devices on the boats, scientists have been able to track these parameters and how they change over time and space.

A new area of study is the use of multiple boats that can communicate with each other to track pollutants, allowing scientists to find locations of oil spills or areas of low oxygen. They can then use this information to investigate further and activate devices such as aerators to help restore acceptable dissolved oxygen levels. In other cases, this information may help with decisions to open spillways to allow greater water movement. In each case, the intention is to use the information on water quality to enhance decision making and ultimately improve water management.

Coastal Restoration Applications
Measuring the effects of coastal restoration efforts can help evaluate their sustainability and cost. A robotic boat equipped with a GPS and a depth-measuring device was developed to measure the erosion of land over time from coastal waterways. The prototype demonstrated the ability to measure depth within a 2-centimeter range, and a newer design being tested has a resolution in the 2-to-5-millimeter range.

Artificial Reefs
In addition to the robotic boats, there are other technologies in use in Louisiana’s coastal wetlands. While Louisiana has 40 percent of the nation's coastal wetlands, 80-90 percent of the nation's coastal wetland loss occurs here, primarily through subsidence, erosion and sea level rise. Many traditional coastal solutions use structures that tend to sink over time and are often not biologically or ecologically friendly. An alternative method is bioengineering to grow coastal structures. This led to the design of low-cost and environmentally friendly artificial reef systems aimed at providing a substrate to encourage the growth of the Eastern oyster. These systems, which often serve as intertidal breakwaters, can reduce coastal erosion, restore coastal habitats and protect wetlands, while the vertical growth of oysters can allow these structures to compensate for sinkage and sea level rise. This growth can simultaneously provide sustainable protection by reducing wave energy and ecosystem services, such as water filtration. Oysters can filter several liters of water per hour, removing carbon and nitrogen from the water column and storing them in their bodies and shells. This could potentially have an impact on local or even regional water quality. For example, the hypoxic zone in the Gulf of Mexico is attributed to a combination of solids and nitrogenous materials, which reduce available oxygen and thus sea life. The filtration of artificial reefs and other bioengineered applications could potentially reduce this problem.

Steven G. Hall is an associate professor and the graduate student coordinator in the Department of Biological and Agricultural Engineering. Daniel Smith, Melody Thomas and Jeanne Steyer are graduate students in that department. Randy R. Price, is an assistant professor at the Dean Lee Research and Extension Center in Alexandria.

The summer 2015 issue of Louisiana Agriculture magazine includes articles on a variety of topics that affect Louisiana’s agriculture industry and the environment – water management at Catahoula Lake, 4-H youth wetland programs, artificial reefs for water conservation, corn nitrogen management in saturated soil conditions, and more. 36 pages

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