Water, Energy, and Biogeochemical Model (WEBMOD), User’s Manual, Version 1 Chapter 35 of Section B, Surface Water, of Book 6, Modeling Techniques Techniques and Methods 6–B35 U.S. Department of the Interior U.S. Geological Survey A B C D E F G H I Front Cover. Forested upland watersheds of the Water, Energy, and Biogeochemical Budget Program (A, F, H, I ) and agricultural watersheds of the National Water Quality Assessment Agricultural Chemical Transport Studies (B, C, D, E, G). A, Luquillo, Puerto Rico; B, Mustang River, California; C, Maple Creek, Nebraska; D, DR2 Drain, Washington; E, Morgan Creek, Maryland; F, Panola Mountain, Georgia; G, Sugar Creek, Indiana; H, Trout Lake, Wisconsin; I, Sleepers River, Vermont. Back Cover. Loch Vale watershed, Rocky Mountain National Park, Colorado. Photograph by Austin Seeback, U.S. Geological Survey (Flickr, U.S. Geological Survey, public domain). Water, Energy, and Biogeochemical Model (WEBMOD), User’s Manual, Version 1 By Richard M.T. Webb and David L. Parkhurst Chapter 35 of Section B, Surface Water Book 6, Modeling Techniques Techniques and Methods 6–B35 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Director U.S. Geological Survey, Reston, Virginia: 2017 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Webb, R.M.T., and Parkhurst, D.L., 2017, Water, Energy, and Biogeochemical Model (WEBMOD), user’s manual, version 1: U.S. Geological Survey Techniques and Methods, book 6, chap. B35, 171 p., https://doi.org/10.3133/tm6B35. ISSN 2328-7055 (online) iii Preface This report describes the U.S. Geological Survey Water, Energy, and Biogeochemical Model. The performance of the program has been tested in a variety of applications. Future applications, however, might reveal errors that were not detected in the test simulations. Users are requested to send notification of any errors found in this report or the model program to: Office of Surface Water U.S. Geological Survey 411 National Center Reston, VA 20192 (703) 648-5001 The latest version of the model program and this report can be obtained using the Internet at address https://doi.org/10.5066/F7P26W9K. v Contents Preface ...........................................................................................................................................................iii Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Development History ............................................................................................................................1 Representation of a Watershed in WEBMOD ..................................................................................2 Capabilities and Limitations ................................................................................................................7 Purpose and Scope ..............................................................................................................................9 Quick Start Guide .........................................................................................................................................10 Obtaining, Installing, and Executing the Software ...........................................................................................................................10 Input Files and Model Output ............................................................................................................10 Dimensions, Parameters, and Variables ................................................................................10 Units .............................................................................................................................................38 Input Files ....................................................................................................................................38 Control File (webmod.control) ........................................................................................38 Hydrologic Data File (webmod.hydro.dat) ....................................................................39 Parameter File (webmod.params) ..................................................................................40 PHREEQC Database File (phreeqc_web_lite.dat) .......................................................40 PHREEQC Input File (webmod.pqi) .................................................................................40 PHREEQC Lookup Table (phreeq_lut) ............................................................................43 Solute Concentration File (webmod.chem.dat) ...........................................................43 Model Output ..............................................................................................................................43 Standard Output ................................................................................................................44 Custom Output and User-Defined Chemical Variables—Chemvars .....................47 Debug File (output/select_mixes) ..................................................................................50 Spatial Properties and Topology of the Watershed ......................................................................51 Andrews Creek Simulation and Calibration ...................................................................................57 Batch Run ....................................................................................................................................58 Interactive Runs .........................................................................................................................58 View Run Time Plots of Simulated and Observed Discharge (steps 1–6; figs. 12A–12C) ..................................................................................68 Add Plots for Snow-Water Equivalence for Two MRUs (steps 7–16; fig. 12D) ...........................................................................................68 Adjust the Rain and Snow Undercatch Factors, rain_adj(nmru,nmonths) and snow_adj(nmru,nmonths), and Evaluate Results (steps 17–31; figs. 12E–12G) .................................................................................................................. 69 Activate Geochemical Simulations and View Variations in Concentrations of Sodium and Silica (steps 32–43; figs. 12G–12H) ........................................70 Increase Surface Area to Volume Ratio for Oligoclase and Evaluate Results (steps 44–45; fig. 12I) ...........................................................................................71 vi Hydrologic Processes .................................................................................................................................71 Initial Conditions..................................................................................................................................72 Energy Balance, Temperature, and Precipitation .........................................................................73 Incoming Solar Radiation .........................................................................................................74 Air Temperature .........................................................................................................................76 Relative Humidity .......................................................................................................................77 Soil and Stream Temperature ..................................................................................................78 Precipitation................................................................................................................................79 Potential Evapotranspiration ...................................................................................................80 Actual Evapotranspiration ........................................................................................................80 Canopy ..................................................................................................................................................80 Snowpack.............................................................................................................................................82 Energy Balance of the Snowpack ...........................................................................................82 Net Radiation Transfer .....................................................................................................82 Latent and Sensible Heat Transfer .................................................................................83