SimBio News: New Paper by SimBiotic Scientist. Urbanization Changes Water Flow and Chemistry
September 30, 2008The hot and dry southwest U.S. has seen its cities grow hugely since the invention of cheap air conditioning. Because they are in the middle of the desert, getting enough water for everyone's needs and wants involves a lot of engineering and redirecting of the streams and rivers that do exist. John Roach, one of our biologists at SimBiotic Software, recently published a paper in BioScience (Roach et al, 2008) from some of his research prior to joining us on how these changes in water flow affect the ecology of the area around Phoenix. Water used to come down into the Phoenix area sporadically, with river beds laying dry most of the year, but flowing during rainy seasons and overflowing during occasional flash floods. During these occasional floods, water flowing through many channels of the stream network would carry large amounts of sediment through the valley and downstream. Much of the water would also rapidly sink into the ground and recharge underground aquifers. John and his co-authors used old photographs and other records to reconstruct how water flows around Phoenix have changed in the last century, and then looked at the effects on all those processes. The upshot was that, maybe not too surprisingly, the quality and flow of water through the Phoenix area has changed a lot. Among other differences, nutrient hotspots have developed, mixing between surface and groundwater is profoundly different, and sediments are now caught in bodies of standing water rather than flowing downstream. These effects might be general to other such arid ecosystems that are have become urbanized. If you're teaching in the southwest U.S., this would be a great paper to use with your students for an ecosystem perspective on how their cities are affecting basic geomorphic processes in your area. It would also make a nice complement to our modules on Sewage, and on Nutrient Cycling, both of which are benefiting from John's expertise as we write new versions.
Read the paper [PDF 5.4MB]
Copyright 2008 American Institute of Biological Sciences. Reprinted by permission.
Read about our Sewage lab