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TITLE:
Measurements and Modeling of the Coupled Groundwater/Vadose Zone/Atmosphere Interactions in the Riparian Corridor of the San Pedro River
INVESTIGATORS:
Russ Scott and Jim Shuttleworth (UA), Dave Goodrich, (ARS), Tom Maddock and Bob MacNish (UA)
OBJECTIVES:
1. To quantitatively estimate the fluxes of water and energy over the two dominant vegetation biomes in the riparian corridor of the upper San Pedro River.
2. To dynamically model the coupled land surface and sub-surface system of the riparian corridor on a regional spatial scale and an annual time scale.
APPROACH:
The first phase of this project focuses on measuring energy and water fluxes over the sacaton and mixed mesquite/grass regions in the riparian corridor. Additionally, vertical transects of water content and temperature in the vadose zone are measured. Most of these data are recorded on a 20-minute interval throughout 1997. The second part of this project concerns the incorporation of this data into a physically-based model of the land surface and subsurface in order to deduce the dominant physical mechanisms that determine the water and energy flux behavior of this region. From this modeling activity, we hope to develop an improved method for computing ET losses in groundwater models and test this method versus the observations being made in the San Pedro Riparian Corridor.
DATA COLLECTION (collected at each of the two sites):
1. Variables: Water and Energy Fluxes (net radiation, ground heat flux, sensible heat flux, latent heat flux, precipitation) over the two vegetation biomes. Method: Bowen Ratio technique with augmentation of missing data from an aerodynamic flux estimation method.
2. Variables: Standard meteorological measurements (wind speed and direction at two heights, incoming solar radiation, air temperature, air pressure, relative humidity, precipitation).
3. Variables: Soil temperature and volumetric water content at 10, 25, 50, 100, 150 (or 200) cm depth. Also, weekly gravimetric water content samples from 0-5 cm. Method: Soil thermocouples and Campbell Scientific CS-615 - water content reflectometers.
DATA REQUIRED FROM OTHER INVESTIGATORS:
1. Groundwater/Aquifer data including aquifer medium characteristics and heads at both the USGS transect wells and piezometers.
2. ET data from the cottonwood/willow gallery.
3. Biome distributions and densities over the entire Upper San Pedro riparian corridor.
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