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Consider the plight of the semi-arid world

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By Roger Snodgrass

A UNESCO prize awarded this week to the water research center SAHRA called attention to an associated project at Los Alamos National Laboratory that is modeling the hydrology of its region.“We work on simulating the water balance of the Rio Grande basin,” said Everett Springer of the lab’s Earth and Environmental Sciences Division in an interview this week. “That’s our role in SAHRA.”SAHRA, the Center for the Sustainability of semi-Arid Hydrology and Riparian Areas at the University of Arizona, was jointly awarded the Great Man-Made River international water prize along with the Center for Hydrometeorology and Remote Sensing at the University of California, Irvine.The award ceremony took place at the World Science Forum in Budapest, where SAHRA Director Jim Shuttleworth accepted the award on Saturday. UNESCO is the United Nations Educational, Social and Cultural Organization.LANL’s project, which is funded through SAHRA by the National Science Foundation, is tracking the hydrosphere of the upper Rio Grande Basin from 1990 to the present. The computational model is known as the Los Alamos Distributed Hydrology System (LADHS).Interactive inputs and outputs to and from ground and surface water are simulated in the model coupled with atmospheric and river-routing components. The period under study covers wet, dry and in-between years, leading up to the present drought, which started in 1999, according to most observers.Currently, LADHS models the upper Rio Grande basin, which begins at the headwaters in southern Colorado and is bounded for this study by the Alameda Bridge in Albuquerque to the south.Springer said the model has a four-to-one advantage over real time.“Basically, we do a day’s simulation in six hours,” he said. “We have to cover a lot of linear area and a lot of complexity, and we’re still learning.”The simulation uses an unusually tight grid, averaging about 100-meters square on the surface, a resolution that is not obtainable without the kind of computing power available at the lab.The project uses a Turquoise Linux Cluster, known as a TLC. About 10 people work part of their time on the project at the laboratory.The ability to obtain realistic projections for how a virtual watershed will perform under varying conditions has implications for managing water resources locally, as well as for scientific applications to other comparable environments around the world.It would be prohibitively expensive, not to mention hazardous, to experiment with a real watershed, but it becomes relatively easy with the computational framework under development at the lab.Experiments by computer can give estimates on scenarios that haven’t been observed, such as the doubling of urban population, changes in land use patterns, an unexpected variation in the climate or the shift to a new climate altogether.Water as a declining resource and as a management problem is a major issue throughout the world, and particularly in developing countries.“One-quarter of the contiguous U.S. and one-third of the earth's land surface is semi-arid or arid land,” according to the prologue for SAHRA’s mission statement. In many parts of the world a combination of population pressures and pollution has produced over-reliance on groundwater reservoirs, the statement continues, while climate change and climate variability have heightened vulnerabilities of a growing percentage of the population to both flood and drought.SAHRA has been involved in UNESCO projects in North Africa, Springer said.The center also maintains an informational hub, G-WADI, the Global Water News Watch, which provides relevant news and information to the international community.On the Valles Caldera National Preserve, SAHRA, LANL and other partners have set up an environmental observatory to monitor the effects of vegetation change on the availability of water resources for human use in the Jemez River Basin.In addition to Los Alamos National Laboratory, SAHRA’s member institutions include Arizona State University, New Mexico Tech, Scripps Institution of Oceanography, United States Geological Survey, the University of New Mexico in Albuquerque and Sandia National Laboratory, among others.