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My research focuses on physical and chemical hydrogeology on land and below the seafloor. My research group and colleagues have completed projects focusing on surface water - ground water interactions, the upper oceanic crust at seafloor spreading centers and on ridge flanks, the hydrogeology of convergent margins, and numerous related processes. We use mapping, seismic, borehole, and thermal data, measure seepage fluxes, and simulate hydrologic processes using numerical and analytical models. Recent highlights include: discovery of hydrothermal flow paths between seafloor basement outcrops separated by >50 km, quantification of surface water - ground water exchange within strongly losing streams, development of a new method for interpretation of shallow thermal data to quantify seepage rates and directions, and conducting the first quantitative crustal-scale, cross-hole hydrogeologic tests in the oceanic crust. I am currently lead proponent for an experiment involving the establishment and use of six long-term, seafloor observatories for multidisciplinary experiments (with a pending drilling expedition and several NSF-supported research projects), and co-PI on a project funded through the Santa Cruz County Resource Conservation District to investigate the benefits to water supply and quality that can be achieved through managed aquifer recharge. These and other projects include field work, laboratory analyses, and modeling. Read about this work in the brief summaries below, and/or follow the link below to abstracts and publications.
I am looking for a new graduate student and/or post-doc to work on a marine hydrogeology project, involving drilling, submersible work, instrument development, and modeling. Please see below and contact me for more information.
Research Projects in Hydrogeology on Land
Research Projects in Marine Hydrogeology
Thinking about joining the UCSC Hydrogeology research group?
The project on land that occupies much of my time these days involved development of tools and methods to help managed aquifer recharge (MAR) so as to simultaneously benefit both water supply and water quality objectives. Enhancements to water supply will help to reduce ground water overdraft, contributing to reductions in the extent of subsidence, seawater intrusion, upflow of lower-quality water from depth, loss from critical surface reservoirs (including streams, lakes, and wetlands), and associated damage to fragile and valuable ecosystems. MAR operations can be run as part of a regional conjunctive use strategy, generating significant benefits to water managers, regulators, stakeholders, and aquatic ecosystems by shifting resource use patterns on the basis of (often unpredictable) availability; this characteristic will become increasingly important in coming decades as climate changes force modification of resource availability and use patterns. Many studies of MAR systems have focused on physical aspects of their operation, particularly causes and impacts of clogging. In contrast, our work focuses on quantitative reduction to nitrate loads during MAR. Improvements to water quality during MAR operations have been documented in a few cases, but this study is unique in combining evaluation of MAR operation with quantitative reductions in nitrate load. We are completing this work as part of the Harkins Slough MAR project, developed and operated by a local water agency to reduce overdraft and its impacts. The project design includes extraordinarily strong control on system mass balance (water, solutes), applies novel technologies and techniques, and provides unique opportunities to link water supply and water quality objectives, and to quantify relations between processes, properties, and MAR. The project comprises a newly-developed collaboration between a local water agency and additional colleagues working at the USGS, Moss Landing Marine Laboratory, University of Alaska Fairbanks, Californina State University - Monterey Bay, and involve numerous graduate and undergraduate student researchers. The main UCSC GSRs are Calla Schmidt, Andrew Racz, and Tess Russo. Undergraduate researchers include Nic Massetani and Johanna Hoffman.
Harkins Slough MAR location map and cartoon showing experimental design:
C. Geoff Wheat (UAF) hold a OsmoSampler system prior to installation in a ground water monitoring well. Graduate Student Researcher, Calla Schmidt (UCSC), and project co-PI, Marc Los Huertos (CSUMB and UCSC) conduct a soil survey and collect samples from the base of the pond during the dry season.
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To the left is the Harkins Slough percolation pond during the 2007-08 recharge season. The pond is not completely full - flat area in the distance can also be covered. Calla Schmidt in full field regalia for sampling of recharge to assess water quality.
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Current weather at the Harkins Slough field site:
Watsonville, CA: 
Another recent project was a multidisciplinary study of the dynamics and impacts of surface water - ground water interaction in the Pajaro Valley, central coastal California. This effort grew out of discussions and observations while I was serving on Technical Advisory Committees for two local water districts, a nice illustration that there can be positive links between service and research. Although surface water and ground water are increasingly understood to comprise a single resource, and the movement of water between surface and ground reservoirs is extremely sensitive to factors such as ground water pumping, stream discharge control, and seasonality and climate change, there is very little information available on factors controlling stream seepage: where it occurs, how variable it is throughout the water year, and how it influences available water quantity and quality. One reason for the lack of data is the difficulty of measuring associated properties and processes in a continuous way. I recruited two graduate students, C. Hatch and C. Ruehl, secured a small grant from the UCSC Committee of Research, and we gathered sufficient data and understanding of the literature to write a successful grant proposal for a more complete project. funded through the U.S. Department of Agriculture's National Research Initiative. This project ran through Summer 2007, ultimately supporting four graduate students and 11 undergraduate student researchers. We also received equipment and field support from the City of Watsonville and in-kind, office, and field support from the Pajaro Valley Water Management Agency, and a grant for isotopic analyses from the UCSC STEPS program. This project is a collaboration between members of the agencies listed above, the USGS., the University of Alaska Fairbanks (Moss Landing campus), and UCSC's Center For Agroecology and Sustainable Food Systems and the Environmental Studies Department. As of Fall 2008, three papers have been published describing results of this project, and first-authored by former students. Additional manuscripts are in progress.
Please see the Publications page for documents describing earlier research projects, including a study of model of mass, energy, and oxygen budgets in a coastal estuary, benthic seepage and its possible impacts on metals contamination in San Francisco Bay, aquifer characterization and the history of regional uplift at former Fort Ord, and aquifer characterization in Pennsylvanian bedrock aquifers in Indiana.
My research group has been involved with several studies of hydrothermal activity on the eastern flank of the Juan de Fuca Ridge, northeastern Pacific Ocean. I sailed to this area as a co-chief scientist on Ocean Drilling Program (ODP) Leg 168 (1996), and as chief scientist of a site survey expedition to prepare for future drilling and experiments (RetroFlux expedition, 2000). The latter program was coordinated with a simultaneous expedition to collect swath map and seismic data (ImageFlux expedition, 2000; chief scientist: V. Spiess, U. Bremen). Studies resulting from these expeditions comprised parts of theses and publications by four UCSC graduate students (J. Stein, E. Giambalvo, G. Spinelli, M. Hutnak). These studies have included in-situ and laboratory permeability tests; comparisons of permeability, heat flow, and seismic data; analysis of large-scale thermal patterns to resolve fluid flow directions and intensity in basement; and computer modeling in which heat flow data, pore-fluid pressures, fluid chemistry, lithostratigraphy, and other data are used to constrain crustal properties. Numerical studies with Stein, Spinelli, Giambalvo, and Hutnak have developed the concept of the hydrothermal siphon as a mechanism for driving massive amounts of hydrothermal fluid through the crust, have shown the importance of the permeability distribution (as opposed to a single bulk value) in guiding flow, and indicate that transient models with well-constrained initial conditions are required to determine fluid flow directions. This work has led to reassessment of many studies and interpretations made during the last several decades. Laboratory work and modeling with Spinelli and Giambalvo has shown the importance of small-scale variations in sediment type and thickness in controlling seafloor hydrothermal seepage, a surface manifestation of underlying convection. Observational work and analytical models published with Hutnak and others have revealed the importance of seamounts in guiding hydrothermal recharge and discharge, helping to resolve a long standing conundrum in global thermal studies: how a large fraction of lithospheric heat is mined from oceanic crust once tens of meters of sediment accumulate across large areas. One set of these results is summarized in the figure that follows.
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Heat flow data were collected adjacent to two basement outcrops on 3.5 Ma seafloor (Fig. A). Heat flow rises abruptly from regional background values adjacent to a discharging outcrop (Baby Bare; Fig B), and drops abruptly adjacent to a recharging outcrop ~50 km to the south (Grizzly Bare, Fig C). Analytical calculations show that hydrothermal circulation between these outcrops can be driven by a "hydrothermal siphon" that sustains fluid flow on the basis of pressure differences between recharge and discharge sites. Numerical calculations show that fluid fluxes consistent with independent estimates are sufficient to match seafloor heat flow and basement temperature patterns, and require effective basement permeabilities on the order of 10-11 to 10-10 m2.
A drilling proposal for which I was lead proponent (with 19 co-proponents from four countries) was selected for the first expedition of the Integrated Ocean Drilling Program (IODP, the successor program to ODP) Expedition 301, June-August 2004, and I served as co-chief scientist (with T. Urabe, U. Tokyo). The complete project includes two drilling expeditions (one being Expedition 301, the other to be scheduled in 2009/10) and a series of submersible and remotely-operated vehicle operations, all in support of hydrogeologic and related experiments. The complete multidisciplinary observational, experimental, and modeling program is designed to evaluate the formation-scale hydrogeologic properties within oceanic crust; determine how fluid pathways are distributed within an active hydrothermal system; and elucidate relations between fluid circulation, alteration, microbiology, and seismic properties. This is to be accomplished through drilling, coring, shipboard and shorebased analysis of recovered materials, downhole logging and active hydrologic experiments, and long-term monitoring of conditions within borehole observatories that extend to 700 m below the seafloor. Cross-hole pumping and tracer experiments will be run during and after the next drilling expedition, allowing crustal-scale properties and transport processes in the ocean crust to be evaluated directly for the first time. I am lead co-PI on NSF proposals funded in 2006 and 2007 that include considerable engineering and instrumentation development, support for multiple submersible expeditions, and analytical and numerical work. GSR Hutnak participated on IODP Expedition 301 and did some of his dissertation work on this project, but there is space and funding available for a new graduate student or post-doc to get involved in this project!
Here you can see images taken aboard the R/V Atlantis and from the submersible DRV Alvin during Summer 2008 observatory servicing operations. The photo on the left shows "shimmering" (64 oC) hydrothermal fluid flowing from Hole 1026B. The Alvin manipulator is holding a gas-tight fluid sampler, which is about to be deployed. The photo on the right shows the ODI underwater connector made up to a data logger, used to record pressure conditions below the seafloor over a period of years.
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Geoff Wheat runs the winch to recover a downhole instrument string. Alison LaBonté shows the newest generation of CORK temperature logger, attached to a thermistor cable. Bosun Wayne Baily prepared to deploy a new thermistor string - this photo shows the deepest OsmoSampler, sinker bar, and drop weight at base.
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I was lead co-PI on another NSF project (with five co-PIs from five institutions) to investigate ridge-flank hydrothermal circulation within 18-24 Ma lithosphere offshore of Costa Rica in the eastern Pacific Ocean. The study area is unusual in that seafloor heat flow over a large region is only 10-30% of that expected for the lithospheric age; in one location, heat flow is 1% of the conductive prediction. There is an abrupt transition between abnormally cool and normal-to-warm seafloor that coincides with a boundary between crust formed at the East Pacific Rise (EPR) and that formed at the Cocos-Nazca Ridge (CNR). This project involved two research expeditions in 2001 and 2002, with seismic, swath-mapping, heat flow measurements, and sediment coring. The first expedition focused on regional features and trends, whereas the second focused on the influence of basement outcrops on hydrothermal circulation. Work during the first expedition demonstrated that the thermal transition between areas of suppressed and elevated heat flow is extremely abrupt and thus must have a shallow, hydrothermal origin. In addition, it appears that basement outcrops (seamouts) also play a critical role in ventilating EPR-generated crust, a process that does not occur on similarly-aged CNR-generated crust of the same age. This observation suggests that there is a fundamental difference in the nature of basement hydrogeology on these two parts of the plate, perhaps with higher and more continuous permeability in fast-spread (EPR) crust. Three UCSC graduate students and two post-doctoral researchers participated on this project (Hutnak, H. Deshon, P. Friedmann, A. Cherkaoui, P.Pizani), as did five UCSC Earth Sciences majors. Seven Earth Sciences majors completed senior thesis on the basis of work associated with this project, the most recent in Spring 2005. One of the most exciting results of this cruise was published in Nature Geoscience in Fall 2008. This paper shows that the flow of warm hydrothermal fluid from outcrops on the cool side of the Cocos Plate extracts as much heat as a black smoker vent field, but at much lower temperatures. Fluid fluxes are thousands of L/s!
I was PI on an NSF-funded project, collaborating with H. Villinger (U. Bremen), to develop a new generation of subseafloor temperature measurment tools for use while piston coring from a drilling platform. The new tools take advantage of recent advances in electronics and computing capabilities and will improve on the quality of acquired data and in interpretations based on these measurements. Previous generations of similar tools have included a sensor and logger package installed within the piston core cutting shoe; the new development will also include design and creation of a new top sub that will permit deployment of two instruments during a single tool lowering, allowing determination of a thermal gradient. I am working cooperatively with Villinger and one of his graduate students, M. Hessemann on: electronics design, prototyping, and testing; modeling of tool response; discussion and transfer of documents between vendors, PIs, and the IODP non-riser, science operator; creation of a front-end interface for tool operation, data acquisition, and processing; construction of working tools; design and construction of two sets of mechanical parts (shoes and top subs); hardware and supplies for testing and tool calibration; calibration at a suitable facility; preparation of a “cookbook” to be used by shipboard technicians and scientists for tool operation; and travel to transfer hardware and software and train technicians and scientists on tool operation. These tools have now been delivered to the U.S. Implementing Organization to IODP, and are being use on both the U.S. and Japanese drilling vessels.
Much of the seafloor hydrothermal circulation modeling work my colleagues and I have completed in the last eight years was facilitated through collaboration with colleagues at Los Alamos National Laboratory (LANL), who have developed a computer code (FEHM) and associated programs that we use to simulate coupled heat-fluid-solute transport. We have modified this code to allow it to represent rock compressibility under non-isothermal conditions and calculate fluid properties (density, viscosity, enthalpy) over a wider P-T range than was possible originally. In addition, we have developed >25 pre- and post-processors for preparation of input and interpretation of numerical results. We are porting an updated version of the modified code to a Linux platform, which should allow us to run more and faster simulations, and are exploring options for conditional simulation.
Join the UCSC Hydrogeology Research Group?
As of Fall 2008 the UCSC Hydrogeology Research Group includes four graduate student researchers (C. Schmidt, A. Racz, T. Russo, and P. Ganguli) and two undergraduate student researchers (N. Massetani, J. Hoffman). We collaborate with researchers and students in the UCSC Environmental Studies Department, University of Alaska Fairbanks, Oregon State University, Los Alamos National Laboratory, University of Bremen, the U.S. Geological Survey, the Pajaro Valley Water Management Agency, University of Miami, University of Utah, University of Illinois, Pacific Geoscience Center (Geological Survey of Canada), Monterey Bay Aquarium Research Institite, Texas A & M University, University of Tokyo, UC Santa Barbara, Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, Lamont Doherty Earth Observatory, and numerous other institutions. Former undergraduate student researchers have been admitted to excellent graduate programs in hydrogeology and related fields and found employment as Earth Science professionals. Former graduate student researchers and postdocs have taken industrial, teaching, not-for-profit, research, and faculty positons throughout the U.S.
Do the projects described earlier on this page sound interesting to you? Perhaps you should think about joining the UCSC Hydrogeology Research group. UCSC is a great institution, the Earth and Planetary Sciences Department is among the best in the world, and Santa Cruz is a wonderful place to live, work, and play. Please read the information below pertaining to your educational and professional status and contact me if you would like to contribute to our research program.
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Postdoctoral Research Opportunities in Hydrogeology at UCSC
Several of the ongoing projects described earlier on this page could benefit from the participation of a postdoctoral researcher. I would consider reprogramming existing funds and/or writing new proposals to support a postdoc for a person with the right skills and interests. In addition, there are experiments that I would like to propose that would make excellent postdoctoral projects. I'll also entertain new ideas from prospective postdocs. Funding sources include the usual NSF programs (including R2K and Margins) as well as NOAA, NASA, EPA, UC Presidential Postdoctoral Program, and others. Ideal candidates will have a background in physical or chemical hydrogeology and/or geophysics and/or computational methods, excellent writing skills, and will be highly motivated. Please contact me if a postdoc with the UCSC Hydrogeology group interests you.
Graduate Research Opportunities in Hydrogeology at UCSC
Four UCSC Hydrogeology graduate students finished in 2007 (R. Sigler, M. Hutnak, C. Hatch, A. Powers), and there is room for one new student entering for the 2008-09 academic year. Most graduate students in my group complete projects that comprise a mixture of lab work, field work, and numerical modeling.
I am most in need of a student collaborator to participate on several marine hydrogeology projects. During the last ten years, these studies have taken us to the northeastern Pacific Ocean and the eastern flank of the Juan de Fuca Ridge, the eastern flank of the East Pacific Rise and the northern flank of the Cocos-Nazca Spreading Center, offshore of Costa Rica, and the Alarcon Basin at the mouth of the Gulf of California. During these studies, we have examined the heat flow, seismic structure, and pore fluid chemistry of ridge-flank sediments and rocks, in collaboration with colleagues from around the world. Most recently, M. Hutnak and I participated on the first expedition of the Integrated Ocean Drilling Program, IODP Expedition 301, during Summer 2004, and I participated on Atlanits/Alvin expeditions to these sites in 2005 and 2008 to swap instrumentation and download data. We have additional Alvin time scheduled for Summer 2009, and are also planning for a short drilling expedition in Summer 2009 to pump cement into two observatories to help seal them. We are now waiting to be allocated additional drilling ship time to complete a multidisciplinary cross-hole experiment within the oceanic crust, including hydrogeologic, seismic, microbiological, and tracer components. This is likely to occur in 2010-11. I currently have NSF funding for these studies, as well as for numerical modeling, and am planning additional proposals and collaborations. There will be opportunities in marine thermal studies, hydrogeologic testing, tracer experiments, and modeling in the next several years.
Three current graduate students (C. Schmidt, A. Racz, T. Russo) are participating on a study of surface water - ground water interactions in the Pajaro Valley (central coastal California), including managed aquifer recharge and processes occurring within constructed wetlands. We are applying a mixture of conventional and novel measurement, sampling, and analytical approaches to quantify the influence of surface water - ground water interactions on water resource quantity and quality, including time-series analysis of thermal data and use of nitrate isotopes to quanitfy seepage impacts. This project involves interaction with an effort to assess nutrient dynamics run through the UCSC Center for Agroecology and Sustainable Food Systems (led by C. Shennan and M. Los Huertos), and interaction with colleagues at local water agencies, USGS, CSUMB, and Moss Landing. Another current student (P. Ganguli) is working on a project to evaluate the influence of surface water - ground water interactions on the speciation, transport, and fate of mercury in a stream impacted by historical mining operations. I have proposals pending to do similar work elsewhere, and may be looking for a new graduate student with experience and/or interests in the chemistry of surface and ground waters and and/or physical hydrogeology. Please note: my highest priority for 2008-09 will be to find a student interested in completing a thesis involving marine hydrogeology, but I will consider starting a new terrestrial hydrology project if I find a suitable student.
Ideal candidates will have an outstanding undergraduate record with a degree in some branch of Earth Science, Engineering, or a related discipline, including considerable quantitative coursework. Honors or a senior thesis are a plus, as are strong writing skills, undergraduate research experience, and the ability to work effectively both alone and in a group, and dedication to doing high-quality work. If you think you may qualify and the projects described above interest you, please contact me.
Undergraduate Research Opportunities in Hydrogeology at UCSC
I have supervised 27 undergraduate student researchers during 2000-07 in field work and lab work, 21 of whom completed a senior thesis in satisfaction of their UCSC "Capstone Requirement." We currently have two undergraduate student researchers working with my lab group. Depending on how various projects and proposals go this year, I may have one or more additional projects for motivated undergraduates. I prefer that students working with my lab group complete a senior thesis as part of a larger project involving me and my other students and research collaborators. Ideal candidates will have an outstanding record of achievement both within and outside the Earth Sciences Department, including quantitative coursework. Successful undergraduate student researchers have strong writing skills, the ability to work effectively both alone and in a group, and committment to their research projects. Prior experience is not necessary. If you wish to be considered, please contact me.
this page last updated: 29-Sep-2008