Category: Research

We are using electrical resistivity tomography to image the dynamic nature of soil moisture, and coupling this with high resolution models to better understand transpiration dynamics and unsaturated flow. We are using time-lapse hydrogeophysical tools to characterize soil moisture variability beneath a range of vegetation types. Those tools include 2D and 3D electrical resistivity tomography (ERT), and ground-penetrating radar (GPR).

We will then combine our measurements with detailed site characterization, point measurements of soil temperature and moisture, and numerical models of hydrological and plant processes to quantify root-zone moisture dynamics with an unprecedented level of detail. Continue reading “Characterizing Soil Moisture Variations in the Unsaturated Zone”

We have developed a novel hydrologic process model called the Integrated Landscape Hydrology Model (ILHM), which is a framework of existing and novel codes to simulate the entire hydrologic cycle at large watershed scales. ILHM is capable of modeling all the major surface and near-surface hydrologic processes including evapotranspiration, groundwater recharge, and stream discharge. In the first published application of the model, the ILHM-modeled stream flows compared favorably with measured data with a minimum of parameter calibration. It was tested for a small watershed (~130 square kilometers) in Michigan, and is currently being applied to much larger domains. Continue reading “Modeling and Monitoring Hydrologic Processes in Large Watersheds”

Related Publications:

Bennett, GL, GS Weissmann, GS Baker, and DW Hyndman, (2006), Regional-scale assessment of a sequence bounding paleosol on fluvial fans using ground penetrating radar, eastern San Joaquin Valley, California, GSA Bulletin, 118, pp 724–732

Solute transport through heterogeneous environments is often poorly understood because of inadequate definition of aquifer stresses and boundary conditions. One approach to address these concerns is to transport a large, minimally disturbed, highly heterogeneous aquifer mesocosm to a controlled laboratory setting. This approach will bridge the gap between small-scale laboratory studies and large-scale field studies.

Ground water chemistry is reflective of time-weighted averages of anthropogenic inputs originating from spatial and temporal patterns of land use. We developed an approach to examine potential relationships between land use-derived solutes and baseflow surface water quality using regional ground water and solute transport models linked to GIS. Our first test of this approach estimated chloride concentrations in surface water due to road salt transport through ground water in Michigan’s Grand Traverse Bay watershed.

Further development of  watershed-scale groundwater flow and transport models  has been undertaken to examine the impacts of various land uses on nitrate concentrations.  In Michigan, streams are predominantly groundwater-fed for much of the year.  Therefore, understanding groundwater nitrate concentrations and fluxes is vital to understanding stream water quality.  The figure on the left shows a preliminary simulation of total N concentrations in Cedar Creek, a small  subwatershed of the Muskegon River in central lower Michigan. Continue reading “Modeling Watershed Scale Groundwater Flow and Geochemistry”

Ground-water contamination with volatile organic compounds is a significant national and international problem. Waters containing these contaminants are typically pumped from contaminated aquifers and treated by air stripping or sorption onto activated carbon. These methods are costly, do not destroy the contaminants, may require pumping and disposal of large water volumes, and do not effectively remove contaminants sorbed to the aquifer material.Accordingly, there has been a great deal of interest in alternative treatment strategies, such as enhanced in-situ remediation. Our research group in collaboration with the Departments of Civil and Environmental Engineering and the Center for Microbial Ecology designed and installed a cost-effective biocurtain that is currently being used to remove carbon tetrachloride from an aquifer in Schoolcraft, Michigan. Novel aspects of the design are the use of closely-spaced wells to recirculate solutes through a biocurtain, well screens spanning the vertical extent of contamination, and a semi-passive mode of operation, with only six hours of low-level pumping per week.

Continue reading “Field Scale Bioremediation Design and Reactive Transport”

A fundamental issue in aquifer biogeochemistry is the means by which solute transport geochemical processes, and microbiological activity combine to produce spatial and temporal variations in redox zonation.  Our Hydrogeology and Hydrogeochemistry groups are examining the temporal variability of TEAP conditions in shallow groundwater contaminated with waste fuel and chlorinated solvents. Continue reading “Interactions Between Hydrologic, Microbial, and Geochemical Processes”

New methods of estimating aquifer properties are needed to improve our understanding of the factors that influence the transport and fate of groundwater contaminants, and to better design remediation systems. Geophysical methods have long been applied to characterize oil reservoirs, while their application to characterize aquifers is much more recent. Our research group is developing a novel set of approaches that combine diverse hydrologic and geophysical data sources to estimate flow and transport properties with the highest resolution possible.

Related Publications:

Continue reading “Estimating Aquifer Properties from Geophysical and Tracer Data”