A finite element groundwater flow model was used to support a hydrologic
assessment for a study area in the Lower San Pedro River Basin which contains the
Bingham Cienega. Consolidated sedimentary rocks associated with an extension of the
Catalina Core Complex truncate the floodplain aquifer system in the study area. The
elevated water table produced by this "hardrock" results in spring discharge at the cienega
and a locally gaining reach of the San Pedro River. The steady -state model suggests that
recharge (and discharge) components for the floodplain aquifer sum to 3.10 cfs. Mountain
front recharge, underflow, and stream leakage are the primary recharge mechanisms, while
stream leakage, evapotranspiration, spring flow, and underflow out are sources for
groundwater discharge. A steady -oscillatory model was used to account for seasonal
periodicity in the system's boundary conditions. Monthly variation in the
evapotranspiration rate was offset primarily by storage changes in the aquifer. Due to a
lack of measured hydrologic data within the study area, results from the model simulations
are only preliminary.
Model development and the subsequent sensitivity analyses have provided insight
into what type of data needs to be collected. Head measurements are most needed in the
area just downstream from Bingham Cienega. The mountain front recharge and
evapotranspiration rates are shown to be highly sensitive parameters in the model;
improved estimation of these values would be helpful. Spring discharge would be a
valuable calibration tool if it could be accurately measured. A more extensive record of
stream baseflow in the San Pedro River should be established. After more hydrologic data
is collected, the model could be recalibrated so as to better represent the system.
Eventually, this tool may be used in direct support of management and/or restoration
decisions.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/615701 |
| Date | 10 1900 |
| Creators | Ronayne, Michael James, Maddock, Thomas, III |
| Contributors | Department of Hydrology & Water Resources, The University of Arizona |
| Publisher | Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ) |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Technical Report |
| Source | Provided by the Department of Hydrology and Water Resources. |
| Rights | Copyright © Arizona Board of Regents |
| Relation | Technical Reports on Hydrology and Water Resources, No. 96-050 |
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