Hester Ecosystem Hydraulics Research Group       

ecohydraulics and pollutant transformation in streams, rivers, and wetlands


Research

 

We are interested in how complexity and heterogeneity in physical structure (topography, substrate composition, large woody debris, floodplain forest patterns) affect water distribution and flows among channel, floodplain, hyporheic, and groundwater environments in stream, river and wetland systems.  Further, we are interested in how such hydrologic patterns interact with human stressors such as climate change and land use conversion (particularly urbanization) to impact various metrics of aquatic ecological health.  When these processes impact water quality, our research also intersects with human health concerns.  In general, our approach to research is to accelerate the development of conceptual understanding by encouraging synergistic feedback between quantitative modeling and flume or field measurements.  We seek out relationships between driving factors and system response, noting nonlinearities and how they can be used to optimize engineering design and landscape management.

Current Research (Example Projects)

  1. Restoration of surface water-groundwater exchange


    This project is evaluating the potential value of restoring hyporheic exchange as a part of stream restoration projects.  Key benefits of hyporheic restoration may include toxics attenuation, nutrient processing, and thermal mitigation, benefitting both ecological and human health in river systems.

    Collaborators: Mike Gooseff, Durelle Scott

    Students: Elizabeth Cranmer, David Azinheira

    Support: National Science Foundation (ENG-CBET-Environmental Sustainability), Award#1066817

    Publications: Hester, E.T., and M.N. Gooseff.  2010.  Moving Beyond the Banks: Hyporheic Restoration Is Fundamental to Restoring Ecological Services and Functions of Streams.  Environmental Science & Technology.  44: 1521-1525.  Link to cover article and feature.

    Hester, E.T. and M.N. Gooseff.  2011.  Hyporheic restoration in streams and rivers.  Chapter in Stream Restoration in Dynamic Fluvial Systems: Scientific Approaches, Analyses, and Tools (Simon, A., S.J. Bennett, and J.M. Castro, Eds.).


  2. Preferential flow at surface water-groundwater interface


    This project is evaluating the significance of preferential flow for surface water-groundwater exchange in stream and river systems.  We are interested in the exchange of water as well as pollutants.

    Collaborators: Adam Ward, Durelle Scott, Cully Hession

    Students: Garrett Menichino

    Support: Jeffress Memorial Trust, Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) Hydrogeophysics Travel Grant, Institute for Critical Technology and Applied Science (ICTAS) at Virginia Tech


  3. Urban heat pulses


    This project is measuring the thermal impact of heated runoff from parking lots during summer storms in receiving streams and wetlands.  This study will help understand how urbanization impacts aquatic organisms, which are often quite sensitive to thermal perturbations.  The project will also help understand how streams and wetlands work, but providing insight into how perturbations propagate through aquatic systems.

    Collaborators: Donald Orth

    Students: Kalen Bauman

    Publications: Hester, E.T., K.S. Bauman, and D.J. Orth.  Impacts of urban heat pulses during summer storms on streams and ponds.  Submitted.

  4. In-stream structures and stream temperature


    This project is utilizing the 3D temperature dataset generated during part 2 of the dissertation (see below) to calibrate a 3D numerical hydraulics and heat flux model.  We plan to use the model to evaluate the effect of varying potential driving factors that were not easily manipulated in the field experiments.

    Students: Garrett Menichino


Dissertation

  1. In-stream structures drive hyporheic hydraulics


    Common in-stream geomorphic structures such as debris dams and steps induce exchange of water between the channel and groundwater (hyporheic exchange).  Exchange is important for ecological stream function, and restoring function is a goal of many stream restoration projects.  This project used numerical models to simulate coupled surface and subsurface hydraulics and evaluate the impact of characteristics of the structure itself and its hydrogeologic setting on induced exchange.  We also conducted a field study to support model results.  Results were published in Hester, E. T., and M. W. Doyle, 2008, In-stream geomorphic structures as drivers of hyporheic exchange, Water Resources Research 44: W03417.  Please email me if you would like a copy of this publication.


    2. Publications: Hester, E.T., and M.W. Doyle.  2008.  In-stream geomorphic structures as drivers of hyporheic exchange.  Water Resources Research  44: W03417.


  2. In-stream structures drive hyporheic heat flux


    Temperature is the most important single condition affecting the lives of organisms and an important regulator of biogeochemical function.   In-stream geomorphic structures are common in natural streams and stream restoration projects, and impact stream thermal regimes in several ways, including by facilitating hyporheic exchange of water and heat between stream channels and underlying sediments.  This project entailed a series of experiments using a variable height weir in a small stream that simulated a debris or log dam.  The height of the weir was varied during the summer and hydraulic and thermal response was measured with a 3D water level and temperature sensor array deployed in surface and groundwater.  Advective and conductive heat fluxes across the streambed in the vicinity of the weir were estimated and compared with other heat budget components.  Results were published in Hester, E. T., M. W. Doyle, and G. C. Poole.  2009.  The influence of in-stream structures on summer water temperatures via induced hyporheic exchange.  Limnology and Oceanography  54(1): 355-367.  Please email me if you would like a copy of this publication.


    3. Publications: Hester, E.T., M.W. Doyle, and G.C. Poole.  2009.  The influence of in-stream structures on summer water temperatures via induced hyporheic exchange.  Limnology and Oceanography  54(1): 355-367.


  3. Sensitivity of stream and river organisms to environmental temperature change 


    Temperature is the most important single condition regulating process rates in organisms.  Human activities like forestry, agriculture, and urbanization increasingly impact stream and river temperatures by modifying discharge, riparian shading, channel form, and climate.  Predicting species response to thermal shifts is necessary to conservation planning.  This project quantified patterns of sensitivity to temperature across taxa and organism processes, and compared to a wide range of human impacts on stream and river temperature.  Results are currently in review at a journal.

    Publications: Hester, E.T., and M.W. Doyle.  2011.  Human impacts to river temperature and their effects on biological processes: a quantitative synthesis.  Journal of the American Water Resources Association.  47(3): 571-587.