Using Multiple Watershed Models to Predict Water, Nitrogen, and Phosphorus Discharges to the Patuxent Estuary 1

We analyzed an ensemble of watershed models that predict flow, nitrogen, and phosphorus discharges. The models differed in scope and complexity and used different input data, but all had been applied to evaluate human impacts on discharges to the Patuxent River or to the Chesapeake Bay. We compared predictions to observations of average annual, annual time series, and monthly discharge leaving three basins. No model consistently matched observed discharges better than the others, and predictions differed as much as 150% for every basin. Models that agreed best with the observations in one basin often were among the worst models for another material or basin. Combining model predictions into a model average improved overall reliability in matching observations, and the range of predictions helped describe uncertainty. The model average was not the closest to the observed discharge for every material, basin, and time frame, but the model average had the highest Nash–Sutcliffe performance across all combinations. Consistently poor performance in predicting phosphorus loads suggests that none of the models capture major controls. Differences among model predictions came from differences in model structures, input data, and the time period considered, and also to errors in the observed discharge. Ensemble watershed modeling helped identify research needs and quantify the uncertainties that should be considered when using the models in management decisions.

[1]  J. Poesen,et al.  Predicting soil erosion and sediment yield at the basin scale: Scale issues and semi-quantitative models , 2005 .

[2]  D. Weller,et al.  Sources of nutrient inputs to the Patuxent River estuary , 2003 .

[3]  Mark Thyer,et al.  Goulburn River experimental catchment data set , 2007 .

[4]  Jeffrey G. Arnold,et al.  Model Evaluation Guidelines for Systematic Quantification of Accuracy in Watershed Simulations , 2007 .

[5]  D. Breitburg,et al.  Preface—From ecology to economics: Tracing human influence in the Patuxent River estuary and its watershed , 2003 .

[7]  W. Dennison,et al.  Nitrogen, phosphorus, silica, and carbon in Moreton Bay, Queensland, Australia: Differential limitation of phytoplankton biomass and production , 2006 .

[8]  Sen Bai,et al.  A water quality model for the Patuxent estuary: Current conditions and predictions under changing land-use scenarios , 2003 .

[9]  K. Boomer,et al.  Empirical models based on the universal soil loss equation fail to predict sediment discharges from Chesapeake Bay catchments. , 2008, Journal of environmental quality.

[10]  J. Brakebill Digital Data Used to Relate Nutrient Inputs to Water Quality in the Chesapeake Bay Watershed, Version 2.0 --Stream Reach Network , 2001 .

[11]  W. Lung,et al.  Eutrophication Model for the Patuxent Estuary: Advances in Predictive Capabilities , 2007 .

[12]  Donald E. Weller,et al.  NONPOINT SOURCE DISCHARGES OF NUTRIENTS FROM PIEDMONT WATERSHEDS OF CHESAPEAKE BAY 1 , 1997 .

[13]  Brian E. Haggard,et al.  PRACTICAL GUIDANCE FOR DISCHARGE AND WATER QUALITY DATA COLLECTION ON SMALL WATERSHEDS , 2006 .

[14]  Limin Yang,et al.  COMPLETION OF THE 1990S NATIONAL LAND COVER DATA SET FOR THE CONTERMINOUS UNITED STATES FROM LANDSAT THEMATIC MAPPER DATA AND ANCILLARY DATA SOURCES , 2001 .

[15]  F. Pappenberger,et al.  Ignorance is bliss: Or seven reasons not to use uncertainty analysis , 2006 .

[16]  Edward E. Leamer,et al.  Let's Take the Con Out of Econometrics , 1983 .

[17]  A. Dezetter,et al.  Simulation of runoff in West Africa: Is there a single data-model combination that produces the best simulation results? , 2008 .

[18]  D. Boesch Challenges and opportunities for science in reducing nutrient over-enrichment of coastal ecosystems , 2002 .

[19]  Bruce A. Robinson,et al.  Treatment of uncertainty using ensemble methods: Comparison of sequential data assimilation and Bayesian model averaging , 2007 .

[20]  Anthony J. Jakeman,et al.  Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM) I: Model intercomparison with current land use , 2009 .

[21]  R. Clark,et al.  Adaptive management of natural resources: theory, concepts, and management institutions. , 2005 .

[22]  Johan Alexander Huisman,et al.  Assessing the impact of land use change on hydrology by ensemble modelling (LUCHEM) IV: Model sensitivity to data aggregation and spatial (re-)distribution , 2009 .

[23]  S. Goetz,et al.  Integrated Analysis of Ecosystem Interactions with Land Use Change: The Chesapeake Bay Watershed , 2013 .

[24]  D. Mason,et al.  Effect of nutrient loading on Atlantic menhaden (Brevoortia tyrannus) growth rate potential in the Patuxent River , 2003 .

[25]  Garey A. Fox,et al.  The Role of Subsurface Flow in Hillslope and Stream Bank Erosion: A Review , 2010 .

[26]  David F. Layton,et al.  Embracing Model Uncertainty: Strategies for Response Pooling and Model Averaging , 2006 .

[27]  J. Brakebill,et al.  Application of spatially referenced regression modeling for the evaluation of total nitrogen loading in the Chesapeake Bay watershed , 1999 .

[28]  P. Sprent,et al.  Query: The Geometric Mean Functional Relationship , 1980 .

[29]  Johan Alexander Huisman,et al.  Analysing the effects of soil properties changes associated with land use changes on the simulated water balance: A comparison of three hydrological catchment models for scenario analysis , 2007 .

[30]  Donald E. Weller,et al.  Relating nutrient discharges from watersheds to land use and streamflow variability , 1997 .

[31]  Robert R. Wells,et al.  Morphodynamics of headcut development and soil erosion in upland concentrated flows. , 2009 .

[32]  Zhi-jun Liu,et al.  EFFECTS OF LAND COVER AND GEOLOGY ON STREAM CHEMISTRY IN WATERSHEDS OF CHESAPEAKE BAY 1 , 2000 .

[33]  N. Lazar,et al.  Methods and Criteria for Model Selection , 2004 .

[34]  K. Staver,et al.  Agriculture and Water Quality on the Maryland Eastern Shore: Where Do We Go from Here? , 2001 .

[35]  Kenneth H. Reckhow,et al.  An Examination of Land Use - Nutrient Export Relationships , 1982 .

[36]  Kuolin Hsu,et al.  A sequential Bayesian approach for hydrologic model selection and prediction , 2009 .

[37]  J. Wickham,et al.  Completion of the 2001 National Land Cover Database for the conterminous United States , 2007 .

[38]  Thomas Maxwell,et al.  Integrated ecological economic modeling of the Patuxent River Watershed, Maryland , 2002 .

[39]  Richard A. Smith,et al.  ERF1 -- Enhanced River Reach File 1.2 , 1999 .

[40]  I. Valiela,et al.  Assessment of models for estimation of land-derived nitrogen loads to shallow estuaries , 2002 .

[41]  Jonathan H. Wright,et al.  Bayesian Model Averaging and Exchange Rate Forecasts , 2003 .

[42]  N. Crawford,et al.  DIGITAL SIMULATION IN HYDROLOGY' STANFORD WATERSHED MODEL 4 , 1966 .

[43]  Zhi-Jun Liu,et al.  A Stream Network Model for Integrated Watershed Modeling , 2008 .

[44]  Peter J. Gleckler,et al.  Evaluation of continental precipitation in 20th century climate simulations: The utility of multimodel statistics , 2006 .

[45]  J. Nash,et al.  River flow forecasting through conceptual models part I — A discussion of principles☆ , 1970 .

[46]  J. Gourley,et al.  A Method for Evaluating the Accuracy of Quantitative Precipitation Estimates from a Hydrologic Modeling Perspective , 2005 .

[47]  Zhi-jun Liu,et al.  Integrated Modular Modeling of Water and Nutrients From Point and Nonpoint Sources in the Patuxent River Watershed 1 , 2008 .

[48]  Penny J Johnes,et al.  A comparison of models for estimating the riverine export of nitrogen from large watersheds , 2002 .

[49]  Anthony J. Jakeman,et al.  Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM) III: scenario analysis , 2009 .

[50]  L. M. Risse,et al.  Sediment fingerprinting to determine the source of suspended sediment in a southern Piedmont stream. , 2010, Journal of environmental quality.

[51]  Thomas Maxwell,et al.  A language for modular spatio-temporal simulation , 1997 .

[52]  Gary Koop,et al.  Measuring the health effects of air pollution: to what extent can we really say that people are dying from bad air? , 2004 .

[53]  Timothy G. F. Kittel,et al.  Validation of Simulated Runoff From Six Terrestrial Ecosystem Models: Results From Vemap , 2004 .

[54]  Bellie Sivakumar,et al.  The more things change, the more they stay the same: the state of hydrologic modelling , 2008 .

[55]  Alexey A. Voinov,et al.  Modular ecosystem modeling , 2004, Environ. Model. Softw..

[56]  Robin L. Dennis,et al.  Cross-Media Models of the Chesapeake Bay Watershed and Airshed , 2000 .

[57]  Ian P. Prosser,et al.  Modelling and testing spatially distributed sediment budgets to relate erosion processes to sediment yields , 2009, Environ. Model. Softw..

[58]  T. Robinson,et al.  Models for Ecological Data: An Introduction , 2008 .

[59]  Christopher A. Barnes,et al.  Completion of the 2006 National Land Cover Database for the conterminous United States. , 2011 .

[60]  J. Brakebill,et al.  Digital data used to relate nutrient inputs to water quality in the Chesapeake Bay watershed , 1999 .

[61]  Limin Yang,et al.  Development of a 2001 National land-cover database for the United States , 2004 .

[62]  Trends and status of flow, nutrients, and sediments for selected nontidal sites in the Chesapeake Bay Watershed, 1985-98 , 2000 .

[63]  T. Jordan,et al.  Phosphorus Burial in Sediments Along the Salinity Gradient of the Patuxent River, a Subestuary of the Chesapeake Bay (USA) , 2010 .

[64]  K. Beven,et al.  A physically based, variable contributing area model of basin hydrology , 1979 .

[65]  P. Kitanidis,et al.  Experimental determination of transverse dispersivity in a helix and a cochlea , 2006 .

[66]  Robert Costanza,et al.  Surface water flow in landscape models : 2. patuxent watershed case study , 1999 .

[67]  Hyosang Lee,et al.  Ensemble predictions of runoff in ungauged catchments , 2005 .

[68]  Gregory E. Schwarz,et al.  Regional interpretation of water‐quality monitoring data , 1997 .

[69]  Zhi-jun Liu,et al.  Effects of land-use change on nutrient discharges from the Patuxent River watershed , 2003 .

[70]  Carl D. Shapiro,et al.  Adaptive management: The U.S. Department of the Interior technical guide , 2009 .

[71]  A. C. Redfield The biological control of chemical factors in the environment. , 1960, Science progress.

[72]  Anthony J. Jakeman,et al.  Ten iterative steps in development and evaluation of environmental models , 2006, Environ. Model. Softw..

[73]  Robert M. Summers,et al.  The validity of a simple statistical model for estimating fluvial constituent loads: An Empirical study involving nutrient loads entering Chesapeake Bay , 1992 .

[74]  A. Raftery,et al.  Atmospheric science. Weather forecasting with ensemble methods. , 2005, Science.

[75]  S. Sorooshian,et al.  Multi-model ensemble hydrologic prediction using Bayesian model averaging , 2007 .

[76]  Adrian E. Raftery,et al.  Weather Forecasting with Ensemble Methods , 2005, Science.

[77]  Anthony J. Jakeman,et al.  Assessing the impact of land use change on hydrology by ensemble modelling(LUCHEM) II: ensemble combinations and predictions , 2009 .

[78]  M. H. Johnson,et al.  FLOW-PROPORTIONAL, TIME-COMPOSITED, AND GRAB SAMPLE ESTIMATION OF NITROGEN EXPORT FROM AN EASTERN COASTAL PLAIN WATERSHED , 2000 .

[79]  D. Merritts,et al.  Natural Streams and the Legacy of Water-Powered Mills , 2008, Science.

[80]  Mingliang Li,et al.  Returns to Schooling and Bayesian Model Averaging: A Union of Two Literatures , 2004 .

[81]  C. Cerco Response of Chesapeake Bay to Nutrient Load Reductions , 1995 .

[82]  J. Brakebill,et al.  A Hydrologic Network Supporting Spatially Referenced Regression Modeling in the Chesapeake Bay Watershed , 2003, Environmental monitoring and assessment.

[83]  Geof H. Givens,et al.  Multicriterion Decision Merging: Competitive Development of an Aboriginal Whaling Management Procedure , 1999 .

[84]  Olivia H. Devereux,et al.  Suspended‐sediment sources in an urban watershed, Northeast Branch Anacostia River, Maryland , 2010 .

[85]  J. Dearing,et al.  Coupling temporal and spatial dimensions of global sediment flux through lake and marine sediment records , 2003 .

[86]  J. Freer,et al.  Diffuse phosphorus models in the United States and europe: their usages, scales, and uncertainties. , 2009, Journal of environmental quality.

[87]  Donald E. Weller,et al.  Effects of agriculture on discharges of nutrients from Coastal Plain watersheds of Chesapeake Bay , 1997 .

[88]  Günter Blöschl,et al.  Hydrologic synthesis: Across processes, places, and scales , 2006 .

[89]  C. Hupp,et al.  Retention of Riverine Sediment and Nutrient Loads by Coastal Plain Floodplains , 2009, Ecosystems.

[90]  Robert M. Hirsch,et al.  Estimating constituent loads , 1989 .

[91]  Johan Alexander Huisman,et al.  Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM) , 2009 .

[92]  D. Phillip Guertin,et al.  Information technology in watershed management decision making , 2004 .

[93]  R. Howarth,et al.  � 2006, by the American Society of Limnology and Oceanography, Inc. Eutrophication of freshwater and marine ecosystems , 2022 .

[94]  Keith Beven,et al.  Towards integrated environmental models of everywhere: uncertainty, data and modelling as a learning process , 2007 .