Agricultural Policy / Environmental eXtender Model User’s Manual Version 0604 BREC Report # 2008-16 June 2008 Agricultural Policy/Environmental eXtender Model User’s Manual Version 0604 E.M. Steglich and J.W. Williams June 2008 BREC Report # 2008-16 Blackland Research and Extension Center 720 East Blackland Road  Temple, Texas 76502 2 CONTENTS THE APEX MODEL—USER’S MANUAL CHAPTER 1 OVERVIEW ...................................................................................................................... 8 1.1 Master File (APEXFILE.DAT) ........................................................................................................... 11 APEX File Name Links .................................................................................................................. 11 CHAPTER 2 INPUT FILES ................................................................................................................... 16 2.1 APEX Run File (APEXRUN.DAT) .................................................................................................... 16 2.2 The APEX Control File (APEXCONT.DAT) ...................................................................................... 18 2.3 The APEX Site Files (FILENAME.SIT) ............................................................................................ 32 2.4 The APEX Site List (SITE****.DAT) ................................................................................................ 35 2.5 The Subarea File (FILENAME.SUB) ................................................................................................. 36 2.6 APEX Subarea List File (SUBA****.DAT) ........................................................................................ 55 How To Build APEX0604 *.sub File ............................................................................................. 56 The Manual Approach: ............................................................................................................. 56 2.7 The Soil Files (FILENAME.SOL) ...................................................................................................... 62 2.8 The APEX Soil List File (SOIL****.DAT) ......................................................................................... 73 2.9 The Operation Schedule Files (FILENAME.OPS) .............................................................................. 74 2.10 APEX Operation Schedule List File (OPSC****.DATA ................................................................. 83 2.11 DAILY Weather Files (FILENAME.DLY) ...................................................................................... 84 2.12 The Daily Weather List File (WDLST****.DAT) ............................................................................ 86 2.13 The Monthly Weather Files (FILENAME.WP1) ............................................................................... 87 2.14 The APEX Monthly Weather Data List (WPM1****.DAT) ............................................................. 90 2.15 The Wind Data File (FILENAME.WND) .......................................................................................... 91 2.16 The Tillage File (TILL****.DAT) .................................................................................................... 94 2.17 The Crop File (CROP****.DAT) .................................................................................................... 100 2.18 The Fertilizer File (FERT****.DAT) .............................................................................................. 116 2.19 The Pesticide File (PEST****.DAT) ............................................................................................... 118 2.20 The APEX Multi-run File (MLRN****.DAT) ................................................................................ 120 2.21 The APEX PARM File (PARM****.DAT)..................................................................................... 122 S-curve parameters ................................................................................................................... 122 S-curve parameter definitions ....................................................................................................... 122 PARM definitions ......................................................................................................................... 125 2.22 The Print File (PRNT****.DAT) ..................................................................................................... 133 2.23 The Herd File (HERD****.DAT) .................................................................................................... 140 CHAPTER 3 OUTPUT DATA VARIABLES .......................................................................................... 145 3.1 *.ASA – Annual Subarea File .............................................................................................................. 145 3.2 *.AWS – Annual Watershed Outlet File .............................................................................................. 146 3.3 *.MAN – Special Manure Management Summary File ....................................................................... 147 3.4 *.DPS – Daily Subarea Pesticide File .................................................................................................. 148 3 3.5 *.WSS – Watershed Summary File ...................................................................................................... 149 3.6 *.ACN - Annual Soil Organic Carbon and Nitrogen File .................................................................... 150 3.7 *.SCX – Summary Soil Organic Carbon and Nitrogen File ................................................................ 151 3.8 *.SUS – Subarea Summary File ........................................................................................................... 152 3.9 *.SWT – Watershed Output to SWAT ................................................................................................. 152 3.10 *.MSA – Monthly Subarea File .......................................................................................................... 153 3.11 *.DHY – Daily Subarea Hydrology File ............................................................................................. 154 3.12 *.SAD – Daily Subarea File ................................................................................................................ 155 3.13 *.DRS – Daily Reservoir File ............................................................................................................. 156 3.14 *.MWS – Monthly Watershed File ..................................................................................................... 157 3.15 *.DWS – Daily Watershed Outlet File ................................................................................................ 157 3.16 *.DGZ – Daily Grazing File ................................................................................................................ 157 3.17 *.DUX – Daily Manure Application File ............................................................................................ 158 3.18 *.DDD – Daily Dust Distribution ....................................................................................................... 158 3.19 *.DCN – Daily Soil Organic Carbon and NItrogen File ..................................................................... 159 3.20 *.ACY – Annual Subarea Crop Yield File .......................................................................................... 159 3.21 *.EFR – Runoff Event Flood Routing File ......................................................................................... 160 3.22 *.EHY – Runoff Event Hydrographs File ........................................................................................... 160 3.23 *.APS – Annual Pesticide File ............................................................................................................ 162 3.24 *.MSW – Monthly Output to SWAT .................................................................................................. 162 3.25 *.DPW – Daily Watershed Pesticide File ........................................................................................... 163 3.26 *.SPS – Pesticide Subarea Summary File ........................................................................................... 163 3.27 *.ACO – Annual Cost File .................................................................................................................. 163 3.28 *.SWN – Special WAtershed Summary for NRCS Farm Planning File ............................................. 164 3.29 *.FSA – Special FSA Annual Subarea File ......................................................................................... 164 3.30 *.SUB – Special Subarea File for GIS ................................................................................................ 166 3.31 *.RCH – Special Reach File for GIS ................................................................................................... 168 CHAPTER 4 APEX OUTPUT ANALYZER ........................................................................................ 171 4.1 Failed runs ............................................................................................................................................ 171 4.2 Problems that may or may not cause failed run ................................................................................... 172 4.3 Problems that cause near 0 crop yield .................................................................................................. 172 4.4 General problems ................................................................................................................................. 172 4.5 Completed runs--examine *.OUT files ................................................................................................ 172 Preliminary investigation ............................................................................................................. 172 Runoff problems--things to check ................................................................................................ 173 4.6 APEX****.out (The detailed simulator output file) ........................................................................... 176 CHAPTER 5 VALIDATION ................................................................................................................ 177 5.1 Validation of Crop Yields .................................................................................................................... 177 5.2 Model Adjustment for Validating Runoff and Sediment Losses ......................................................... 179 Method 1: For the Layman User .................................................................................................. 179 Method 2: For the Technical User ................................................................................................ 180 APPENDICES…………………………………………………………………………181 Appendix A—Watershed Definitions ......................................................................................................... 183 Appendix B—Subarea Definitions .............................................................................................................. 185 Appendix C—Watershed Name Definitions ............................................................................................... 191 Appendix D—Watershed Subarea Definitions ........................................................................................... 192 4 Appendix E—Adding Subarea(s) ................................................................................................................ 195 Appendix F—Manning’s N Surface Roughness (UPN) ............................................................................. 198 Appendix G—Routing Reach & Channel Manning’s N (RCHN & CHN) ................................................. 199 Appendix H—Parm Definitions .................................................................................................................. 200 Appendix I—APEX publications ................................................................................................................ 206 Appendix J—APEX Balances Variable Definitions ................................................................................... 212 REFERENCES ............................................................................................................... 216 5 7 CHAPTER 1 OVERVIEW APEX is a tool for managing whole farms or small watersheds to obtain sustainable production efficiency and maintain environmental quality. APEX operates on a daily time step and is capable of performing long term simulations (1-4000 years) at the whole farm or small watershed level. The watershed may be divided into many homogeneous (soils, land use, topography, etc.) subareas (<4000). The routing component simulates flow from one subarea to another through channels and flood plains to the watershed outlet and transports sediment, nutrients, and pesticides. This allows evaluation of interactions between fields in respect to surface run-on, sediment deposition and degradation, nutrient and pesticide transport and subsurface flow. Effects of terrace systems, grass waterways, strip cropping, buffer strips/vegetated filter strips, crop rotations, plant competition, plant burning, grazing patterns of multiple herds, fertilizer, irrigation, liming, furrow diking, drainage systems, and manure management (feed yards and dairies with or without lagoons) can be simulated and assessed. Most recent developments in APEX0604 include:  Flexible grazing schedule of multiple owners and herds across landscape and paddocks.  Wind dust distribution from feedlots.  Manure erosion from feedlots and grazing fields.  Optional pipe and crack flow in soil due to tree root growth.  Enhanced filter strip consideration.  Extend lagoon pumping and manure scraping options.  Enhanced burning operation.  RUSLE soil loss simulation  Carbon pools and transformation equations similar to those in the Century model. 8 Data Structure. The framework of the APEX data structure consists of three files— APEXFILE.DAT, APEXCONT.DAT, and APEXRUN.DAT. APEXFILE is a list of the file names that are used in the run and provide a reference for APEX in determining what data is to be used for each run. APEXCONT contains data that controls the run i.e. run length, option selections, defaults, etc. APEXRUN is a list of run names and numbers that specify the site, weather parameter, and subarea files. An overview of the files and data flow is given in Figure 1.1. Note: in the following, where filename.* is used, this indicates that the user may supply the file name, with the appropriate * extension; those file names must be listed appropriately in APEXFILE.DAT). Constant Data. The APEXCONT.DAT file contains parameters that will be held constant for the entire study, e.g., number of years of simulation, period of simulation, output print specification, weather generator options, etc. This file cannot be renamed. Sites. The study may involve several sites (fields, farms, or watersheds). A file named filename.sit is used to describe each site. SITECOM.DAT (or user chosen name) is used to reference the numbered list of the sites and their file names. Weather. Weather stations are numbered and identified in WPM1MO.DAT, and wind data for the stations are numbered and identified in WINDMO.DAT. WPM1MO.DAT (or user chosen name) and WINDMO.DAT (or user chosen name) are used to reference the numbered list of the weather stations and their file names. A file named filename.wp1 is used to describe each weather station statistics while a file named filename.wnd is used to describe each wind station statistics. Subarea. Each site in the study may involve several subarea arrangements (e.g. fields/subareas with or without buffers and filter strips, etc.). A file named filename.sub is used to describe each subarea or Hydrologic Landuse Unit (HLU), which is homogenous with respect to climate, soil, landuse, and topography. The subareas may be linked with each other with respect to the water routing direction towards a single or multiple watershed or farm outlet(s) (explained later in the documentation). Within each filename.sub the user needs to specify a dominant soil and operation schedule for each subarea from the list of soils in SOILCOM.DAT and list of operation schedule in OPSCCOM.DAT. SUBACOM.DAT (or user chosen name) is used to reference the numbered list of the subareas and their file names. Soils. The study may involve several different soils for the farm or watershed analysis. A file named filename.sol is used to describe each soil and the SOILCOM.DAT file (or user chosen name) is used to reference the numbered list of the soils and their file names. Operation Schedules. Each subarea or field of the watershed or farm study is described with a unique landuse unit or operation schedule (e.g. crops and crop rotations with typical tillage operations, ponds or reservoir, farmstead with or without lagoon, etc.). Each operation schedule is in a file named filename.ops. Each operation schedule must be numbered and listed in the OPSCCOM.DAT (or user specified file), which is used as a reference to the numbered list of the operation schedules and their file names. Execution of Runs. Once all of the files have been set up properly, APEX0604, a compiled FORTRAN program, can be executed by opening a DOS command prompt window, changing to the directory where the program files have been copied, and typing the command “APEX0604.exe”. 9 Output files (35 per run) Figure 1.1: APEX0604.DAT File Structure .out standard output .swt SWAT output Input files: .man manure summary .sad daily subarea file .sus subarea summary .rcd daily reach file .asa annual subarea output .sot soil output .dps daily pesticide file .dgz daily grazing file APEXCONT.DAT SITECOM.DAT (default) .msa monthly subarea file .drs daily reservoir file Control File, setting parameters that are .wss watershed summary .aps annual pesticide constant for entire study or group of runs. APEXBUF.out special .aco annual cost SUBACOM.DAT (default) .mws monthly watershed file .dws daily watershed file .aws annual watershed outlet file WPM1US.DAT (default) APEXFILE.DAT .dux daily manure application file (associates 15 *.DAT file APEX0604.exe .ddd daily dust distribution .can annual soil organic C&N WINDUS.DAT (default) names) Internal File Reference .dcn daily soil organic C&N File Name to be used .scx summary soil organic C&N .acy annual subarea crop yield CROPCOM.DAT (default) .efr runoff event Flood Routing SITECOM.DAT .ehy runoff event Hydrographs (default) APEXRUN.DAT .msw monthly SWAT output TILLCOM.DAT (default) .dpw daily watershed pesticide file List of Sites (Number Run # (one line per run) .sps pesticide subarea summary and Filename.sit) Site # .swn watershed summary for NRCS farm planning PESTCOM.DAT (default) Monthly Weather Station # .fsa annual FSA subarea .sub special subarea file for GIS Wind Weather Station # .rch special reach file for GIS FERTCOM.DAT (default) Subarea # .dhy daily subarea hydrology file Filename.sit Daily Weather Station # (one file per site) SOILCOM.DAT (default) SUBACOM.DAT OPSCCOM.DAT (default) Filename.sub (default) WINDUS.DAT WPM1US.DAT (one file per subarea) List of Subareas (default) (default) TR55COM.DAT (default) SOIL # (number and List of Wind Weather List of Monthly OPSC # Filename.sub) Stations (number and Weather Stations PARM0604.DAT (default) Filename.wnd) (number and Filename.wp1) MLRN0604.DAT (default) OPSCCOM.DAT SOILCOM.DAT PRNT0604.DAT (default) (default) (default) Filename.wnd Filename.wp1 List of Operation List of Soils (Number (one file per wind (one file per Monthly HERD0.DAT (default) Schedules (Number and Filename.sol) weather station) Weather Station) and Filename.ops) WDLSTCOM.DAT WDLSTCOM.DAT Filename.dly (default) (default) (one file per daily List of Daily Weather Filename.ops Filename.sol weather station) Stations (number and (one file per (one file per soil) operation schedule) Filename.dly) 10