First-Ever Global Water Permeability Map

EarthzineEarthly Updates, Original, Water

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A high-resolution water permeability map of North America. Image Source: MouthToSource.In a study done by the University of British Colombia, researchers have been able to produce the first-ever world surface permeability map measuring the flow of water through rocks and sediments. According to a report published Jan. 21 in Geophysical Research, this map will help support better climate modeling and improved water resources management, and is expected to contribute to a more thorough understanding of geological processes.

Previously, water surface permeability data only measured 1-2 meters below ground in small areas. This study has provided results that yield measurements up to 100 meters below ground, spanning the world. The map produces a resolution of 13,000 kilometers-squared for the world, and a resolution of 75 kilometers-squared for North America.

The map was constructed with lithology, or rock type, data from researchers at the University of Hamburg and University of Utrecht. An abstract of the report states that ‰ÛÏpermeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction.‰Û

Previous climate models have not used groundwater or underlying sediments and rocks in their data. However, with the creation of this map, scientists can now update climate models to incorporate this data. Groundwater is an important aspect in measuring climate change and climate predictability models because it composes 99% of all fresh, unfrozen water. Similarly, groundwater feeds surface water and moistens the root zone of terrestrial plants, also affecting climate.

Global permeability map as well as a higher resolution North American map. Image Source: SciDev courtesy of Geophysical Research Letters. One of the main reasons this permeability map has become important is because it puts together hydrogeological models from the world, rather than just regions. Tom Gleeson, a postdoctoral researcher with the Department of Earth and Ocean Sciences of the University of British Colombia, says in a SciDev article, “This is the first global-scale picture of near-surface permeability, and is based on rock type data at greater depths than previous mapping.” The research study was funded by the Natural Sciences and Engineering Research Council of Canada, German Science Foundation, and Utrecht University.

On a related note, the U.S. Environmental Protection Agency (EPA) undertook a study in October 2009 to measure runoff pollution from different types of paved surfaces.

“Runoff from parking lots and driveways is a significant source of water pollution in the United States and puts undo stress on our water infrastructure, especially in densely-populated urban areas,” EPA Acting Regional Administrator George Pavlou says in an e! Science News article.

The EPA replaced a 43,000-square-foot parking lot in Edison, New Jersey, with three different types of pavements. In the next 10 years, they will measure how effective each pavement is in filtering out the pollutants from storm water as it permeates into the ground. The reason behind this study is that the EPA feels there is a ‰ÛÏlack of full-scale, outdoor, real-world permeable pavement research projects.‰Û