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| Background | Watershed Description | Why the GSLB? | Science Themes | Data and Infrastructure | Research | Participants |
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Scaling Role of the Great Salt Lake on Atmospheric Moisture Fluxes within the Basin The size of the proposed Great Salt Lake Hydrologic Observatory provides an opportunity to study atmospheric moisture fluxes at a meaningful scale. Uncertainty in the current understanding of precipitation and atmospheric moisture fluxes within the basin has led to the following questions: To what extent do the Great Salt Lake and surrounding salt playas impact precipitation in meteorologically down-gradient mountains relative to that arising from larger-scale atmospheric moisture fluxes into the Basin? What roles do lake water evaporation and heating of overlying air masses play in down-gradient precipitation? How do these roles change with lake volume?
Characterization of Groundwater Residence Times Understanding regional groundwater residence times and fluxes is crucial in establishing the overall water balance in the Great Salt Lake Basin. In addition, residence times are important in determining the sensitivity of ground water to pollution. Shorter residence times may indicate recent recharge and higher sensitivity. Longer residence times may represent a greater travel time and increased geologic protection. The following questions related to groundwater residence times have been proposed:
Does integration of this distribution lead to a meaningful recharge rate? Can the spatial distribution and recharge rate of groundwater be linked to lake volume fluctuation? How much groundwater flux contributes to base flow in mid- and high-elevation streams? Recently obtained groundwater age data in the Salt Lake basin east of the Wasatch Mountains are depicted in the figure at right (USGS, 2004). The change in age as a function of distance (age gradient) provides a direct measure of groundwater velocities and recharge rates (Manning, 2002). Noble gas thermometry has shown that the majority of groundwater in the basin is sourced in the mountain block. As such, the age data constitute a type of geochemical tomography in that they reflect (provide an "image" of) processes occurring in the adjacent (but not directly sampled) mountain block.
USGS. 2004. Water Quality in the Great Salt Lake Basins Utah, Idaho, and Wyoming 1998-2001. National Water-Quality Assessment Program. Circular 1236. Manning, A.H. 2002. Using noble gas tracers to investigate mountain-block recharge to an intermountain basin. Ph.D. dissertation, University of Utah. 187 pp.
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SCALING.
To what extent do the Great Salt Lake and surrounding salt playas impact precipitation in meteorologically down-gradient mountains relative to that arising from larger-scale atmospheric moisture fluxes into the Basin?
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Due to its large size, the Great Salt Lake has a significant effect on the weather of nearby cities. Snowfall in the surrounding area is influenced by the Great Salt Lake, which appears to produce localized snow bands several times each winter. Such snow bands are known locally as "lake effect bands," and can produce some of the region's most intense winter storms. During the winter, the lake is warmer than the air above it. This increases the moisture content of the air, creates thermal instability, and causes natural seeding of salt crystals. These factors are hypothesized to cause the fall and winter "lake effect," in which areas adjacent to and usually downwind from the lake receive greater snowfall than those more distant. This phenomenon has been the subject of some debate and continues to perplex operational and research meteorologists.
