Publications

Decadal changes in groundwater quality in two study units on the north-central California coast were evaluated by the Priority Basin Project (PBP) of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. Groundwater samples collected from wells during 2004–05 were compared on a pair-wise basis to samples collected from the same wells during 2014. The data set consisted of...

Review of previous investigations indicates that potential decreases in groundwater recharge and increased groundwater extraction in the vicinity of the Lower Des Plaines River Valley in Will County, Illinois, may reduce the amount of groundwater flow in the Silurian aquifer in this area. Groundwater discharge from the Silurian aquifer to wetlands in the Lower Des Plaines River Valley...

Effects of discharge variability on point-bar sedimentation are not well documented, although resulting changes in flow patterns are well known. This paper focuses on a meander of Powder River in Montana (USA). In May 1978, Powder River had a 50-year recurrence flood, which caused outer bank retreat of ∼70 m. This bank continued to retreat over ∼40 m in response to annual floods between...

Mechanisms by which hydrochemical changes occur after earthquakes are not well documented. We use the 2016–2017 central Italy seismic sequence, which caused notable hydrochemical transient variations in groundwater springs to address this topic, with special reference to effects on fractured carbonate aquifers. Hydrochemistry measured before and after the earthquakes at four springs at...

Coastal marine habitats become contaminated with the munitions constituent, Hexahydro-1,3,5-trinitro-1,3,5-trazine (RDX), via military training, weapon testing and leakage of unexploded ordnance. This study used 15N labeled RDX in simulated aquarium-scale coastal marine habitat containing seawater, sediment, and biota to track removal pathways from surface water including sorption onto

An exploratory discrete Bayesian network (BN) was developed to assess the potential of this type of model for estimating the magnitudes and uncertainties of an arbitrary subset of unmeasured water-quality parameters given the measured complement of parameters historically measured at a U.S. Geological Survey streamgage. Water-quality data for 27 water-quality parameters from 596 discrete

Secure, reliable, and sustainable water resources are fundamental to food production, energy independence, and the health of humans and ecosystems. But the large-scale development of fresh groundwater resources has stressed aquifers in some areas, causing declines in the amount of groundwater in storage and decreases in discharge to surface-water bodies like rivers and springs (Reilly...

Fine sediment (particles

We investigated interfacial processes affecting metal mobility by wood ash under laboratory-controlled conditions using aqueous chemistry, microscopy, and spectroscopy. The Valles Caldera National Preserve in New Mexico experiences catastrophic wildfires of devastating effects. Wood samples of Ponderosa Pine, Colorado Blue Spruce, and Quaking Aspen collected from this site were exposed...

Tritium is a radioactive isotope of hydrogen (half-life is equal to 12.32 years). Since it is part of the water molecule, tritium can be used to track and date groundwater and surface water when the history of tritium in precipitation and recharge is known. To facilitate that effort, tritium concentrations in precipitation were reconstructed from measurements and correlations for 10...

In 2010, the Natural Resources and Environmental Systems Hydrology Committee (NRES-21) of ASABE initiated a long-term process to develop guidelines to improve modeling practice through better understanding of the calibration, validation, and evaluation process across applications and more effective interpretation and communication of model performance. This effort generated a compilation...

High-frequency, long-term monitoring of water quality has revolutionized the study of surface waters in recent years. However, application of these techniques to groundwater has been limited by the ability to remotely pump and analyze groundwater. This paper describes a novel autonomous groundwater quality monitoring system which samples multiple wells to evaluate temporal changes and...