The work reported herein constitutes a final report for a project funded by the U.S. Department of Interior, Office of Water Resources and Technology, Grant No. 14-31-0001-4218.
Elevated groundwater nitrate (NO3
-) concentrations in the Southern Willamette
Valley (SWV) caused the Oregon Department of Environmental Quality (ODEQ) to
declare a Groundwater Management Area (GWMA) in Spring, 2004. To better
understand direction of groundwater flow, groundwater age, and nitrate transport
pathways of the SWV we developed a steady-state...
Water is one of the most biologically and economically important substances on Earth. A significant portion of Earth's water subsists in the subsurface. Our ability to monitor the flow and transport of water and other fluids through this unseen environment is crucial for a myriad of reasons.
One difficulty we...
It is becoming increasingly important to understand fundamental hillslope-scale hydrological processes. Most hillslope-sale transport experiments have generally focused on conceptual findings or other aspect of flow behavior, rather than the quantification of the mass transport mechanisms of advection and dispersion. When the velocities have been quantified, dispersion has been mentioned...
The specific objectives of this dissertation are to determine subsurface flow
behaviors across different antecedent wetness conditions from a top-down perspective
and to mechanistically assess the hydrological controls on DOC and N transport at the
hillslope and catchment scale. The study area is a small catchment where hillslopes
issue directly...
Simulations of stream-subsurface water exchange (hyporheic exchange) using a three-dimensional steady state groundwater flow model and a particle tracking model in unconstrained and constrained reaches of small (2nd-order) and intermediate (5th-order) mountain streams were conducted to estimate the effects of geomorphic features on the extent, volume and residence time of...
This study was undertaken to gain further
understanding of the subsurface hydrology for a stream-adjacent
riparian area in Western Oregon's Coast Range.
Spatial and temporal fluctuations of the free water
surface of a toeslope, adjacent riparian area, and stream
channel in a forested terrace reach were monitored over a
period...
This dissertation re-examines the now standard perceptual model of hillslope
hydrological response to rainfall, which includes the growth of a saturated wedge at the soil-bedrock interface or impeding layer. It also challenges the notion of bedrock impermeability and the assumption that the pattern of subsurface stormflow is determined by the...
The dominant controls on flow generation in steep, forested hillslopes are poorly understood. This dissertation examined the dominant flow processes operating at the hillslope scale, using a combined macroscale measurement and model development and analysis framework. Irrigation experiments at two steep forested hillslopes were conducted to isolate individual hillslope flow...