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The project focuses on the use of analytical techniques that we have developed to support a wide range of studies in water-rock interaction, integrating solid phase mineralogy and elemental chemistry and clay mineralogy into hydrologic and contaminant studies.
Categories: Project; Tags: Contaminants, Mineralogy
The “Hydroecology of Flowing Waters” project was initiated in 1998 with the aim to improve understanding of how stream and river corridors function naturally in ways that produce valuable ecosystem services (e.g. flood attenuation, carbon and nutrient storage and contaminant removal, habitat value for fish and wildlife, recreation). The research is increasingly focused on how aquatic ecosystem services can be better protected in the face of degradation resulting from accelerating land use and climate change. Central to the research is the investigation of interactions between physical and biological processes, e.g. how land use change affects hydraulics and channel geomorphology in ways that produce cascading...
Various processes within the unsaturated zone affect ground-water availability and portability, as well as concentrations of water vapor and trace gases in the atmosphere. The rate at which precipitation or applied irrigation water infiltrates, its redistribution following infiltration, and the partitioning of the redistributed soil moisture between ground-water recharge and evapotranspiration affect the rate at which the ground-water reservoir is replenished and the degree to which ground water might be contaminated by chemical applications, spills, or disposal. Consequently, knowledge of and methods to quantitatively measure and predict these processes are needed to determine the impact of such societal practices...
The objectives of my current research are to 1. Understand the water quality effects of fire, 2. Measure the effects of fire on the carbon cycle and other biogeochemical cycles, 3. Characterize the combustion products of wildfire, mainly ash and charcoal, and 4. Link post-fire responses and the composition, physical characteristics, and reactivity of ash and charcoal to measures of burn severity detected on the ground or using remotely-sensed data. The overarching objective of my research is to understand runoff, erosion, deposition, and water quality effects after wildfire.
Watershed-scale water quality and water availability are affected by the interaction between the landscape and surface and subsurface flows at multiple scales. Wide-spread agriculture leads to diffuse non-point sources of contamination by agricultural chemicals. Localized exchanges of surface water and groundwater through highly reactive streambeds can attenuate the impact of agricultural chemicals on water quality. Thus, understanding the patterns and trends in water quality within a watershed requires analyses at multiple scales to understand hydrologic processes and the integration of hydrology and water quality information. The main objective of my research is to develop a better understanding of the role of...
Using long-term data records, this project is focused on two problems of importance to water resources managers. First, long-term streamflow records are being used to a) identify broad regional to national trends in floods and low-flows and relate them to possible causes (climate change, water management changes, land-cover changes, and ground-water level change) and b) determine whether there are patterns that relate to watershed size or climate characteristics. It is often stated in the popular press and in official publications on global climate change that we can expect increased variability, including larger and/or more frequent floods, and deeper and longer droughts, as a result of greenhouse warming. This...
Our research focuses on developing methods to analyze volcano-hydrothermal systems and on the application of these methods to particular volcanic systems in the western United States. Specific research questions include (1) What are the modes of heat and mass transport from magma to the shallow subsurface? (2) What are the pressure, temperature, and fluid-saturation conditions between magma and the land surface? (3) What controls the permeability of volcanoes? How does it vary in space and time? What role do temporal variations in permeability play in the evolution of volcanogenic hydrothermal systems and episodes of volcanic unrest? (4) How well-coupled are various fluid flow, transport, and mechanical deformation...
Understanding the effects of climatic variability is important to development of water resources, mitigation of flood hazards, and interpretation of geomorphic surfaces. Climatic variability, which is characterized by temporal changes in variability of seasonal climate that spans decades or centuries, may be more important to water-resources evaluations than changes in mean climatic conditions. Changes in variability of climate has a large effect on the probability of occurrence of extreme events, such as floods or droughts. Understanding of climatic variability and its effect on the landscape is of paramount importance for estimation of flood frequency, sediment transport rates, and long-term watershed and channel...
This project is focused on developing objective methods for evaluating USGS hydrologic-data-collection activities; such methods are needed so that activities can be modified when necessary and the efficiency of USGS operations maximized.
Categories: Project; Tags: Statistical Hydrology
The goal of my biodegradation research is to understand the processes controlling the rate of biodegradation of contaminants in the subsurface. This understanding will form the basis of methods to increase degradation rates without causing further degradation of groundwater quality. Recent work has focused on the fate of crude oil and agricultural nitrate contamination in the subsurface. Specific objectives for the crude oil research include: (a) determine the rate that contaminants are transported from the source zone; (b) provide an estimate of how long the spilled oil will continue to pollute the groundwater; and (c) determine the fate of products of biodegradation or so-called “secondary water quality impacts”...
Modeling of watershed response to normal and extreme climatic conditions or to changes in the physical conditions of a watershed requires the simulation of a variety of complex hydrologic processes and process interactions. Some of these processes are well understood at a point or for a small area; others are poorly understood at all scales. Increasing spatial and temporal variability in climate and watershed characteristics with an increase in watershed area adds significantly to the degree of difficulty in investigating and understanding these processes. Research is needed to better define these processes and to develop techniques to simulate these processes and their interactions at all watershed scales. Project...
Toxic contaminants and naturally occurring substances found in the subsurface can exist in multiple phases, and undergo complex reactions including biodegradation. A comprehensive and quantitative understanding of the processes controlling the fate and transport of subsurface contaminants is necessary to develop policies and strategies for managing water-quality conditions in different land use and environmental settings. Numerical models that simulate flow, transport, and reactions are useful tools for understanding the fate of chemicals in the subsurface when used in conjunction with field and laboratory studies. The research efforts of this project consider flow and chemical behavior in the saturated and unsaturated...
To study the mechanisms, pathways, and rates of transformation of carbon and nitrogen compounds (natural and contaminant) mediated by microorganisms in aquatic habitats and identify factors controlling these transformations and to examine the effect that these transformations have upon other biogeochemical processes.
1) Improve predictions of streamflow at ungaged basins, and 2) understanding the causes of streamflow changes due to human changes to the environment, and 3) establish biological-flow relations.
Quantitative understanding of groundwater and gas-rich fluid- and thermodynamics in volcanic areas is important for several reasons: 1) as a major source of hazard such as propellant in steam-driven explosions, lubricant in mudflows, and transport agent for toxic constituents such as arsenic and mercury that are dissolved from fresh volcanic rock, 2) groundwater pressure, temperature and chemical changes might signal one of the earliest warnings of volcanic unrest, 3) exploration and mining of geothermal energy and mineral deposits. Many of the geochemical, geodetic, and seismic signals measured at the ground surface as part of the volcano monitoring strategies have hydrothermal origins or magmatic origins modulated...
Much work has been done to track spilled oil and study its fate and its effect on the environment. Our studies involved developing and applying methods to identify and track spilled oil as it weathers, as well as to differentiate it from other petrogenic hydrocarbon input sources, as well as differentiating petrogenic sources. This work in identifying petroleum sources, both natural and anthropogenic, has a great deal of transfer value to other estuarine systems.
Categories: Project; Tags: Contaminants, Organic Compounds
The overall objective of the MoWS research group is to gain better understanding of the precipitation-runoff processes and use this knowledge to develop improved hydrologic models. The main research topics include: 1) Add functionality and improvements to the MoWS simulation models being developed and integrate with other hydrologic, hydraulic, and climate models. 2) Enhance the models to use the best and latest topographic, climate, geologic, and land-use data sets as direct input to process algorithms to increase the physical nature and temporal and spatial resolution of model input. 3) Develop national model structure and calibration strategy for national model application.
The objectives of my research are (1) to synthesize observational estimates of continental water and energy fluxes and storage; (2) to construct global computational models of continental water and energy fluxes and storage; (3) to identify physical controls, natural and anthropogenic, on spatial and temporal variability of water and energy fluxes and storage; and (4) to elucidate the hydrologic causes and effects of Earth-system variability and change, including climatic, biospheric, and geodetic processes.
Our research seeks to evaluate and understand the processes that control and respond to changes in the level of CO 2 in the atmosphere. Our interests include the natural cycling of CO 2 and carbon through plants, soils, seawater, rocks, and sediments. We study the causes and effects of past geologic changes in atmospheric CO 2 levels, and the ongoing effects of human actions on CO 2 and climate.
The purpose of my research group is to develop new methods and applications of environmental isotopes to solve problems of national importance. In specific, the overall goal is to use environmental isotopes, combined with other biogeochemical measurements and hydrologic and biogeochemical modeling, to increase our understanding of biogeochemical and hydrological processes, nutrient and organic matter sources, subsurface flowpaths, and water age distributions in diverse environments. Many of our studies piggyback on the sampling efforts of major monitoring programs to investigate causes of hypoxia and food web problems. Our work provides critical scientific support for these monitoring programs. A long-term career...