Impacts of an Upstream Dam and Ground-Water Pumping on Stream Temperature
Abstract
The combined effects of the presence/absence of an upstream boundary dam and in-reach groundwater pumping on stream temperature under different climate conditions were analyzed over the entire year. Stream temperatures were simulated using the CE-QUAL-W2 water quality model over a 110-kilometer model grid, with the presence/absence of a dam at the top of the reach and groundwater pumping in the lower 60- kilometers of the reach. Measured hourly meteorological data from three representative locations in the western United States were used as model input to replicate humid, semiarid, and arid climate conditions. For each climatic condition four hypothetical flow scenarios were simulated, which included: (1) natural, (2) upstream dam only, (3) upstream dam with in-reach groundwater pumping, and (4) upstream dam removed with in-reach groundwater pumping. Analysis of simulations indicated the impact of dam removal with or without groundwater pumping resulted in significant changes in stream temperature throughout the year for all three climate conditions. From March to August 2001 the presence of a dam caused monthly-mean stream temperatures to decrease 3.0, 2.5, and 2.0 C on average compared with natural conditions for the humid, semiarid, and arid conditions, respectively; however, stream temperatures generally increased relative to natural conditions from September to December. Due to its smaller impact on streamflow, the cessation of groundwater pumping resulted in more subtle temperature changes compared with temperature changes caused by the dam. During the summer and winter stream temperatures were respectively cooler and warmer by generally less than 0.5 C compared with natural conditions. Of potential ecological significance, presence of either a dam or ground-water pumping significantly altered the spatial extent of streamflow by creating transient dry reaches for several semiarid- and arid-climate simulated conditions.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2009
- Bibcode:
- 2009AGUSM.H73C..05R
- Keywords:
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- 1829 Groundwater hydrology;
- 1830 Groundwater/surface water interaction;
- 1860 Streamflow