| Abstract: | Wells completed in an unconfined aquifer in the Closed Basin Division of the San Luis Valley Project, Colorado, are expected to provide about 101,800 acre-ft of groundwater/year to the Rio Grande when this project is completed. Lowering of groundwater levels in the unconfined aquifer is expected to decrease the quantity of groundwater that is lost by evapotranspiration. The aquifer system, which consists of an unconfined aquifer that is 50 to 130 ft thick, overlies a thick, leaky confined aquifer. Groundwater moves from the edge of the valley toward a topographic low near the center of the Closed Basin Division, where it is lost by evapotranspiration. A two-dimensional groundwater flow model was used to evaluate the effects of projected withdrawal of about 141 cu ft/sec by 168 wells throughout a 20-year period. The simulated pumpage resulted in a projected drawdown greater than 0.1 ft in the water-levels of the unconfined aquifer over an area of about 370 sq mi. Maximum simulated drawdown was 25 ft. Simulations indicate that about 66 % of the water to be withdrawn from the unconfined aquifer would be derived from decreases of evapotranspiration, 26% from induced leakage from an underlying confined aquifer, and 8% from storage of the unconfined aquifer. Model simulations were based only on withdrawals from wells completed in the unconfined aquifer. Pumpage from the confined aquifer was not simulated. Upward leakage from the confined aquifer predicted by the model, results from the simulated declines of the potentiometric surface in the unconfined aquifer. (USGS) |
| Genre: | USGS Numbered Series |
| ProdID: | 28321 |
| Citation Author: | Leonard, G. J.; Watts, K. R. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | vii, 42 p. :ill., maps ;28 cm. |
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| Citation Publisher: | U.S. Geological Survey, |
| Citation Series: | Water-Resources Investigations Report |
| Citation Series Code: | WRI |
| Citation Series Number: | 87-4284 |
| Citation Search Results Text: | Hydrogeology and simulated effects of ground-water development on an unconfined aquifer in the Closed Basin Division, San Luis Valley, Colorado; 1988; WRI; 87-4284; Leonard, G. J.; Watts, K. R. |
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| Citation Year: | 1988 |
| Type: | citation/reference |
| Text: | Hydrogeology and simulated effects of ground-water development on an unconfined aquifer in the Closed Basin Division, San Luis Valley, Colorado; 1988; WRI; 87-4284; Leonard, G. J.; Watts, K. R. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wri/1987/4284/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wri/1987/4284/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey, |
