Zachary Easton


Ph.D., Hydrology, Cornell University, 2007

M.S., Hydrology, Cornell University, 2004

B.S., Soil Science, University of Massachusetts, 2004


August 2016 - Present - Associate Professor and Extension Specialist, Department of Biological Systems Engineering, Virginia Tech

April 2011 - July 2016 – Assistant Professor and Extension Specialist, Department of Biological Systems Engineering, Virginia Tech

December 2008 – April 2011 – Research Associate, Department of Biological and Environmental Engineering, Soil and Water Lab, Cornell University

January 2007 – December 2008 – Postdoctoral Research Associate, Dept. Biological and Environmental Engineering, Soil and Water Lab, Cornell University

Selected Major Awards

  • 2014 – Outstanding Assistant Professor, College of Engineering, Virginia Tech
  • 2013 – Outstanding Reviewer, ASCE
  • 2009 – Cornell University Soil and Water Group receives the USDA- CSREES Partnership Award for Mission Integration.

Courses Taught Last Five Years

  • BEE 6740 - Ecohydrology, Cornell University
  • BEE 4730 - Introduction to Watershed Modeling, Cornell University
  • BEE 4370 - Introduction to Watershed Modeling, Joint Cornell University-Bahir Dar University (Ethiopia)
  •  BEE 4960 - Geographic Information Systems for Hydrology, Cornell University

Other Teaching and Advising

I serve as a faulty advisor to a Senior Design team (BSE 4125-4126 Comprehensive Senior Design Project) tasked with designing and implementing a wastewater treatment system in the Dominican Republic.

Program Focus

My research addresses both native and managed systems, considers processes at plot- to large river basin-scales, and is relatively evenly divided among field study/monitoring, modeling, and application of results to real world problems. Current projects focus on several areas, such as: 1) How do land use and climate (change) impact water quality? Work here focuses on characterization of the relationships between land use distributions and patterns of nutrient and water flows in the landscape and used this information to predict stream water quality/quantity.  2) How do agricultural and urban management practices affect water quality? This work integrated plot and field scale research with basin scale modeling to assess the impact of best management practices. One of the roles has been to develop and test basin scale hydrologic models designed to provide accurate estimates of both water quality and quantity. 3) What processes control the fate and transport of nutrients and sediment? Recent work has focused on assessing influence of anaerobic conditions on denitrification in a denitrifying bioreactor designed to treat diffuse ground water nitrate. Our hope is to better define engineering guidelines so that conditions in the bioreactor foster complete denitrification (e.g., N2 gas is the end product and not NOx). 4) Can we bridge basic research and modeling to management and application? For instance, results from past research efforts are currently being considered in New York, Wisconsin, and Minnesota to drive policy decisions on fertilizer use in urban systems.

Current Projects

  • Twenty-first century development of 21st century precision agriculture for water quality protection. USDA-AFRI. This project aims to develop a dynamic real time Decision Support System (DSS) that provides information relevant to water quality protection. A unique feature of the proposed DSS is that it will predict runoff risks in real-time and forecast risks 6-hrs to 3-days into the future.  These risks are displayed on Google-map-like images on smart phones.
  • NSF-WSC-Category-1: Collaborative Proposal: Coupled Multi-scale Economic, Hydrologic, and Estuarine Modeling to Assess Impacts of Climate Change on Water Quality Management. The overarching goal of this project is to develop a quantifiable, predictive framework that couples biogeochemical and hydrologic drivers of terrestrial nutrient export with climate change to evaluate the effects of ecosystem management on estuarine function and costs of water quality protection. To achieve this goal, we propose to work broadly across common regional Chesapeake Bay watershed physiographic gradients and dominant landuses (e.g., agriculture, forest and urban). The following goals will allow us to develop a this framework based on our best current knowledge, explore the impact of climate change and extreme weather events on nutrient and sediment export, and develop new modeling paradigms to improve water quality models used for management decisions.
    1. Bracket the mid-century changes in climate for the Chesapeake Bay watershed with downscaled high-resolution regional climate models.
    2.  Evaluate likely changes in landscape patterns and magnitudes of N and P cycling and erosion using downscaled climate model outputs coupled to multi-scale landscape models.
    3.  Investigate how climate change and alternative nutrient management strategies affect water quality in the Chesapeake Bay.
    4.  Assess tradeoffs between costs of Best Management Practices (BMPs) and landscape management intended to control nitrogen (N) loadings and variability of N loadings under alternative climate change scenarios

  • NSF-WSC-Category-3: Collaborative Proposal:Impacts of Climate Change on the Phenology of Linked Agriculture-Water Systems. Our proposed research is based on the premise that climate induced changes in the timing of agricultural practices  that may seem insignificant when analyzed in isolation  have the potential to create disproportionately large effects on downstream watersheds and ecosystems due to their interactions with other climate induced changes. Our objective is to explore various aspects of this premise  and, in the course of so doing, to develop new approaches and  understanding of the following four research elements of the  system, and the links between them. Here, we seek improved  understanding of:
    1. How a change in climate affects farmers’ decisions about land use and timing of agricultural practice (human phenology);
    2. How a change in climate, agricultural practice, and land-use  affects watersheds’ intra-annual variability of water, sediment, and nutrient export (watershed phenology);
    3. How changes in timing, location, and watershed inputs affect estuary physical and biological response, including the severity of  hypoxia (estuarine phenology); and
    4. How policy designed to influence agricultural land use and practice to mitigate ecosystem impacts can account for these cascading human, biological, and physical effects in water systems.
  • NSF-EarthCube Building Blocks: A Broker Framework for Next Generation Geoscience. We are developing  a Broker Framework of the Geosciences which addresses the need for effective and efficient multi-disciplinary collaboration through the introduction of brokering as an EarthCube building block. The need for expanded collaboration has increased as science addresses the complex challenges of understanding and predicting Earth’s environment. The issues, identified as Grand Challenges by the NSF in their GEOVision report, are: “Understanding and forecasting the behavior of a complex and evolving Earth system” and “Reducing vulnerability and sustaining life.” This same report highlights that an “integrated and interdisciplinary approach in the geosciences will lead to new paradigms for human interactions with the Earth and guide us to solution-oriented applications.” EarthCube (EC) is the NSF GEO flagship initiative identified in the GEO Vision to create a new generation of information infrastructure. EC aims to transform the conduct of research through the development of community-guided cyberinfrastructure to integrate information and data across the geosciences.
  • Decreasing Nitrogen and Phosphorus in Drainage Waters Using a Comprehensive Drainage Management Approach.Controlling nutrient loss from artificially drained agricultural lands on the Atlantic Coastal Plain requires a comprehensive approach that includes field and drainage management practices to address production and water quality concerns. Previous research by the project team has demonstrated significant nitrogen (N) and phosphorus (P) reduction with conventional and novel management practices, e.g., flow control structures, gypsum curtains, biofilter reactors. This project seeks to integrate field and drainage management practices to develop, demonstrate and test a comprehensive approach to drainage management that can be readily adopted by producers on the Coastal Plain.
  • Refining P Indices in the Chesapeake Bay Region to Improve Critical Source Area Identification. Despite the apparent success of the P Index concept, there remain concerns about the effectiveness of the Indexing approach for attaining water quality goals. One of the major concerns that has been raised is that the transport component of many P indices is either not well developed, or unimportant (i.e., in some P Indices the transport scales from 0 to 1 and the source from 0 to 100 or more). Our regional project seeks to refine P management via the P Index concept, specifically:
    1. Evaluate P Indices by comparing their output with water quality monitoring data and fate-and-transport models.
    2. Use water quality data (monitored or predicted by model) to refine P Indices, improving their prediction of P loss potential, ensuring consistency across state boundaries and within physiographic provinces, and promoting effective recommendations for P management.
    3. Predict the management impact of P Indices on nutrient management practices and water quality.

Program Focus

Extension and outreach are critical activities. Two core issues of focus when developing extension programs and materials are:

  1. Maintain a strong problem-solving focus in extension programs with emphasis on both increased environmental quality and economic viability
  2. Stakeholder driven technology transfer coupled with education to identify, develop, and apply natural or engineered solutions to address various soil and water resource management concerns and environmental policy issues.  

Locally, I serve as a member of the Plasticulture Committee and a member of the VA-DCR Watershed Network Committee. Regionally, I contribute as an instructor at the Mid-Atlantic Crop Management School. I also serve on a joint committee with the National Fish and Wildlife Foundation (NFWF), USDA Conservation Innovation Grant (USDA-CIG) system and the US-Environmental Protection Agency (EPA) to assess the utility and feasibility of technologies such as active denitrification management and biomass to energy projects to reduce watershed nutrient mass balances in the Chesapeake Bay. Nationally, I serve on the USDA-NRCS-SERA 17 P index Task Force to advise the NRCS on reworking the P-Index standards.

Current Projects

  • Twenty-first century development of 21st century precision agriculture for water quality protection. USDA-AFRI. This project integrates both tool development and stakeholder driven modifications to the tool (see above).

Selected Recent Publications

(*student or postdoc, chronological)

  • Easton, Z.M., P.J. Kleinman, A.R. Buda, D. Goering, N. Emberston, S. Reed, P.J. Drohan, M.T. Walter, P. Guinan, J.A. Lory, A.R. Sommerlot*, A. Sharpley. 2017. Short-term forecasting tools for agricultural nutrient management. J. Environ. Qual. (In Press).
  • Sharpley, A., P. Kleinman, C. Baffuat, Z.M. Easton, J. Lory, D. Osmond, T. Veith. 2017. Verification of Phosphorus Site Assessment Tools: Lessons from The U.S.  J. Environ. Qual. (In Press).
  • Rees, G.*, E.M. Bock*, K. Stephenson, and Z.M. Easton. 2016. Nutrient biofilters in the Virginia Coastal Plain: Nitrogen removal, cost, and potential adoption pathways. J Soil and Water Conserv. (In Press).
  • Wagena, M.B.*, A.R. Sommerlot*, E.M. Bock*, D.R. Fuka*, and Z.M. Easton. 2017. Development of a nitrous oxide routine for the SWAT model to assess greenhouse gas emissions from agroecosystems.  Environ. Model. Software.
  • Sommerlot. A.R.*, M.B. Wagena*, D.R. Fuka* and Z.M. Easton. 2016. Coupling the short-term Global Forecast System weather data with a variable source area hydrologic model. Environ. Model. Software.​1016/​j.​envsoft.​2016.​09.​0081364-8152.
  • Wagena, M,B.*,  A. Sommerlot*, A. Abiy, D.R. Fuka*, A.S. Collick*,  S. Langan, and Z.M. Easton. 2016. Regional climate change In the Blue Nile Basin: Implications for water resource availability and sediment transport. Climatic Change. doi: 10.1007/s10584-016-1785-z.
  • Fuka, D.R.*, A.S. Collick*, P. Kleinman, D. Auerbach*, D, Harmel, Z.M. Easton. 2016. Improving the spatial representation of soil properties and hydrology using topographically derived initialization processes in the SWAT model. Hydrol. Proc. doi: 10.1002/hyp.10899.  
  • Auerbach, D.*, Z.M. Easton, M.T. Walter, A.S. Flecker, D.R. Fuka*. 2016. Evaluation of alternative weather forcing for hydrologic modeling in tropical basins of Puerto Rico. Hydrol. Proc. doi:10.1002/hyp.10860.
  • Collick, A.S.*, T.L. Veith, D.R. Fuka*, P.J.A. Kleinman, A.R. Buda, J.L. Weld, R.B. Bryant, P.A. Vadas, M.J. White, D. Harmel, and Z.M. Easton. 2016. Improved simulation of edaphic and manure phosphorus loss in SWAT. J. Environ. Qual. doi:10.2134/jeq2015.03.0135
  • Bock, E.M.*, B. Coleman*, and Z.M. Easton. 2016. Effect of biochar on nitrate removal in a field-scale denitrifying bioreactor. J. Environ. Qual. doi: 10.2134/jeq2015.04.0179.
  • Easton, Z.M., M.E. Rogers*, J.M. Davis*, M. Eick and E.M. Bock*. 2015. Mitigation of sulfate reduction and nitrous oxide emission in denitrifying environments with amorphous iron oxide and biochar. Ecological Engineering.
  • Kleinman, P.J.A., D.R. Smith, C.H. Bolster, and Z.M. Easton. 2015. Phosphorus fate, management and modeling in artificially drained systems. J. Environ. Qual. 44:460-466. doi:10.2134/jeq2015.02.0090.
  • Radcliffe, D.E., D.K. Reid, K. Blomback, C.H. Bolster, A.S. Collick*, Z.M. Easton, W. Francesconi, D.R. Fuka*, H. Johnsson, K. King, M. Larsbo, M.A. Youssef, A.S. Mulkey, N.O. Nelson, K. Persson, J.J. Ramirez-Avila, F. Schmieder, and D.R. Smith. 2015. Applicability of models to predict phosphorus losses in drained fields: A review. J. Environ. Qual. 44:614-628. doi:10.2134/jeq2014.05.0220.
  • Rittenburg, R.A.*, A.L. Squires*, J. Boll, E. Brooks, Z.M. Easton, and T.S. Steenhuis. 2015. Agricultrual BMP Effectiveness and dominant hydrological flow paths: Concepts and a review. J. Am Wat. Res. Assoc. doi:10.1111/1752-1688.12293.
  • Brooks, E.S., S.M. Saia, J. Boll, L. Wetzel, and Z.M. Easton. 2015. Assessing BMP effectiveness and guiding BMP planning using process-based modeling. J. Am Wat. Res. Assoc. doi:10.1111/1752-1688.12296.
  • Boll, J., T.S. Steenhuis, E.S. Brooks, L. Kurkalova, R.A. Rittenburg, A.L. Squires, G. Vellidis, Z.M. Easton, and J.D. Wulfhorst. 2015. Featured collections introduction: Synthesis and analysis of Conservation Effects Assessemtn Projects for improved water quality. J. Am Wat. Res. Assoc. doi:10.1111/1752-1688.12297.
  • Bock, E.*, N. Smith*, M. Rogers*, B. Coleman*, M. Reiter, B. Benham, and Z.M. Easton. 2015. Nitrate and phosphate removal and nitrous oxide production in lab-scale denitrifying bioreactors. J. Environ. Qual. 44:605-613. doi:10.2134/jeq2014.03.0111.
  • Collick, A.S.*, D.R. Fuka*, P.J.A. Kleinman, A.R. Buda, J.L. Weld*, M.J. White, T.L. Veith, R.B. Bryant, C.H. Bolster, and Z.M. Easton. 2015. Predicting phosphorus dynamics in complex terrains using a variable source area hydrology model. Hydrol. Proc. DOI: 10.1002/hyp.10178.
  • Hoskins, T.C.**, J.S. Owen, J.S. Fields**, J.E. Altland, Z.M. Easton and A.X. Niemiera. 2014. Solute transport through a pine-bark based substrate under saturated and unsaturated conditions. JAHS. 139(6):634-641.
  • Fuka, D.R.*, M.T. Walter, C.A. MacAllister, and Z.M. Easton. 2014. SWATmodel: A Multi-OS, Multi-Platform SWAT Model Package in R. J. Am Water Res. Assoc. 1-5. DOI: 10.1111/jawr.12170
  • Woodbury, J., C.A. Shoemaker, D. Cowan, and Z.M. Easton. 2014. A Comparison of SWAT models for the Cannonsville Watershed with and without variable source area hydrology. J. Am Water Res. Assoc. 1-15. DOI: 10.1111/jawr.12116.
  • Fuka, D.R.*, C.A. MacAllister, A.T. Degaetano, and Z.M. Easton. 2013. Using the Climate Forecast System Reanalysis dataset to improve weather input data for watershed models. Hydrol. Proc. DOI: 10.1002/hyp.10073.
  • Easton, Z.M. 2013. Defining spatial variability of hillslope infiltration characteristics using geostatistics, error modeling and autocorrelation analysis. J. Irrig.  Drain. Eng. ASCE. 139(9) 718-727, DOI:10.1061/(ASCE)IR.1943-4774.0000602
  • Dahlke, H.E., Z.M. Easton, D.R, Fuka*, M.T, Walter, and T.S. Steenhuis. 2013. Real-time forecast of hydrologically sensitive areas in the Salmon Creek Watershed, New York State, using an online prediction tool. Water. 5, 917-944; doi:10.3390/w5030917.
  • Flores-López, F., Z.M. Easton, L.D. Geohring, P.J. Vermeulen, V.R. Haden, and T.S. Steenhuis. 2013. Factors affecting phosphorous in ground water in an alluvial valley aquifer: Implications for best management practices. Water. 5. 2013. 540-559; doi:10.3390/w5020540.
  • Pradhanang, S., R. Mukundan, E.M. Schneiderman, M. Zion, A. Anandhi, D.C. Pierson, A. Frei, Z.M. Easton, D.R. Fuka*, and T.S. Steenhuis. 2013.  Streamflow responses to projected climate change in New York City water supply watershed. J. Am Water Res. Assoc. 1-19. DOI: 10.1111/jawr.12086.
  • Buchanon, B.P., Z.M. Easton, R. Schneider and M.T. Walter. 2013. Modeling the hydrologic effects of roadside ditch networks on receiving waters. J. Hydrol. doi: 2013.01.040.
  • Buchanan, B.P., J.A. Archibald, Z.M. Easton, S.B. Shaw, R.L. Schneider, and M.T. Walter. 2013. A Phosphorus Index that combines critical source areas and transport pathways using a travel time approach.  J. Hydrol.
  • Caballero, L.A., Z.M. Easton, B.K. Richards, And T.S. Steenhuis. 2013.  Evaluating the hydrological impact of a cloud forest in Central America using a semi-distributed water balance model. J. Hydrol. and Hydromech. 61, 2013, 1, 9 – 20 DOI: 10.2478/jhh - 2013-0003.
  • Saia, S., E.S. Brooks, Z.M. Easton, C. Baffaut, J. Boll, T.S. Steenhuis. 2013. Incorporating pesticide transport into the WEPP-UI model for mulch tillage and no-tillage soil with an underlying claypan. Trans ASCE Applied Engineering in Agriculture.  29(3):363-372.
  • Tilahun, S.A., R. Mukundan, B.A. Demisse, T.A. Engda, C.D. Guzman, B.C. Tarakegn, Z.M. Easton, A.S. Collick, A.D. Zegeye, E.M. Schneiderman, J.Y. Parlange, and T.S. Steenhuis. 2013. A saturation excess erosion model. Trans. ASABE 56(2): 681-695.
  • Buchanon, B.P., K. Falbo, R. Schneider, Z.M. Easton, and M.T. Walter. 2013. Hydrologic impact of roadside ditches in an agricultural watershed: Implications for non-point source pollutant transport. Hydrol. Proc. 10.1002/hyp.9305.
  • Caballero, L., A. RImmer, Z.M. Easton, and T.S. Steenhuis. 2012. Rainfall runoff relationships for a cloud forest watershed in Central America: Implications for water resource engineering. J. Am Water Res. Assoc.  20 JUN 2012 | DOI: 10.1111/j.1752-1688.2012.00668.x
  • Buchanon, B.P., Z.M. Easton, R. Schneider and M.T. Walter. 2012. Incorporating variable source area hydrology into a spatially distributed direct runoff model. J. Am. Water Res. Assoc. 48(1): 43–60. DOI: 10.1111/j.1752-1688.2011.00594.x
  • Fuka, D.R.*, Z.M. Easton, E.S. Brook, J. Boll, T.S. Steenhuis, and M.T. Walter. 2012. Process-based snowmelt modeling: Integration into the SWAT model. J. Am. Water Res. Assoc. DOI: 10.1111/j.1752-1688.2012.00680.x
  • Dahlke, H.E., Z.M Easton, S. Lyon, L.D. Brown, M.T. Walter, and T.S. Steenhuis. 2012. Dissecting the variable source area concept - Subsurface flow pathways and water mixing processes in a hillslope. J Hydrol. doi:10.1016/j.jhydrol.2011.11.052.
  • Rao, N.S., Z.M. Easton, D.R. Lee, and T.S. Steenhuis. 2012. Economic analysis of best management practices to reduce watershed phosphorus losses. J. Environ. Qual. doi:10.2134/jeq2011.0165.
  • Dahlke, H.E., Z.M. Easton, M.T. Walter, T.S. Steenhuis. 2012. A field test of the variable source area interpretation of the Curve Number rainfall-runoff equation. J. Irrig. Drain. Eng. ASCE. Vol. 138, No. 3, ISSN 0733-9437/2012/3-235–244.
  • Easton, Z.M., M.T. Walter, D.R. Fuka, E.D. White, T.S. Steenhuis. 2011. A simple concept for calibrating runoff thresholds in quasi-distributed variable source area watershed models. Hydrol. Proc. doi:10.1002/hyp.8032, 2011.
  • White, E.D., Z.M. Easton, D.R. Fuka, A.S. Collick, E. Adgo, M. McCartney, S.B. Awulachew, Y.G. Selassie, and T.S. Steenhuis. 2011. Development and application of a physically based landscape water balance in the SWAT model. Hydrol. Proc. 25:915-925. doi:10.1002/hyp.7876, 2011.
  • Marjerison, R.D., Z.M. Easton, H.E. Dahlke, and M.T. Walter. 2011. A P-Index transport factor based on variable source area hydrology for New York State. J. Soil Water Conserv. 66(3):149-157; doi:10.2489/jswc.66.3.149.
  • Flores-López, F., Z.M. Easton, L.D. Geohring, and T.S. Steenhuis. 2011. Factors affecting dissolved phosphorus and nitrate concentrations in ground and surface water for a valley dairy farm in the Northeastern United States.  Water Environ. Res. 8392:116-127.

Selected Recent Funding

  • "Pratt Endowment." Hannigan, M., Z.M. Easton, R. White. Integration of livestock feeding strategies into a nutrient loading, watershed model. $186,600. January 2017-December 2020.
  • "USDA-NRCS Conservation Innovation Grant." Easton, Z.M Revising and Implementing Phosphorus Indices to Protect Water Quality in the Northeast US. $96,000. January 2017-December 2020.
  • "USDA-NRCS Conservation Innovation Grant." Emberston, N., Z.M. Easton, M.T. Walter, P. Kleinman. Demonstration and Implementation of a Nutrient Management Risk Advisory System for Protection of Water Quality in Runoff Prone Climates. $529,376. September 2015-September 2018.
  • "NSF Water Sustainability and Climate Cat-3."Ball, W., Z.M. Easton, C. Harman, L. Waigner, W. Kemp, D. Brady. WSC-Category 3 Collaborative Proposal: Impacts of Climate Change on the Phenology of Linked Agriculture-Water Systems. $1,432,854.  June 2014-May 2018.
  • "NSF Water Sustainability and Climate Cat-1." Easton, Z.M., R. Najjar, M. Li, D. Sample, D. Bosch. WSC-Category 1 Collaborative Proposal: Coupled Multi-scale Economic, Hydrologic, and Estuarine Modeling to Assess Impacts of Climate Change on Water Quality Management. $600,000. June 2014-May 2017.
  • "Delmarva Land Grant Institution Collaborative Research Seed Funding Program." Shober, A., Z.M. Easton, A. Allen, A. Buda, R. Bryant. Combining electrical resistivity imaging and conservative tracer tests to characterize and model subsurfact phosphorus losses in ditch-drained Delmarva soils. $26,000. January 2015-December 2018.
  • "EPA Center for Nutrient Solutions." Shortle, J., R. Brooks, B. Bills, B. Boyer, A. Kremanian, R. Ready, M. Royer, T. Richard, D Beegle, A. Allen P. Kleinman, C. Duffy, Z. Easton, A. Buda, T. Veith.  Center for integrated Multi-scale Nutrient Solutions. $4,550,740. August 2103-July 2017.