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Dam methane

Methane Production at Little Nerang in Queensland, Australia.

A visualization of Little Nerang dam in Queensland, Australia. Lines or red or yellow show methane concentration, with high conentration in the lower right-hand side of the dam. Image courtesy of the Queensland Cyber Infrastructure Foundation.

Water storages, such as dams for hydroelectric power or for drinking water, are major sources of methane, a greenhouse gas with 21 times the global warming potential of carbon dioxide.

After the initial flooding of a new dam, a large amount of organic matter - mostly trees and plants that died in the flood - settles to the bottom. There, it decomposes without oxygen, resulting in a build up of methane in the water that can be released as methane gas if there is significant movement in the water. After this phase of initial flooding, the methane production can still continue because variation in water depth between seasons and years means that decaying organic matter is often added to the water.

Researchers have only identified and begun to understand these emissions from water over the last 10 years or so. But, now, as greenhouse gas accounting measures are being introducted, water regulation bodies are facing a new challenge in trying to measure and control methane emissions from dams.

In Queensland, Australia, data was collected at the Little Nerang dam by Seqwater, South East Queensland’s bulk water supply provider, and the CSIRO, the Australian science research organisation. Data - in the form of bathymetry, sonar and LiDaR - identified pockets of methane, and measured water movement, dam landforms and the vegetation which was above the waterline.

Then, the  data was brought to life with the help of the Queensland Cyber Infrastructure Foundation as a comprehensive 3D representation of a physical model built from multiple sensor types (the bathymetry, sonar, and LiDAR data) to allow non-expert policy makers and stakeholders understand how the methane is produced.

As well as helping to account for greenhouse gas emissions, the researchers hope the visulation tool will help improve water quality models - thus leading to lower water treatment costs.

This visulization application can now be used for other multi-dimensional data sets as well, the researchers said.

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