Peterson, S.M., Flynn, A.T., and Traylor, J.P., 2016, Groundwater flow model of the Northern High Plains aquifer in Colorado, Kansas, Nebraska, South Dakota, and Wyoming: U.S. Geological Survey Scientific Investigations Report 2016–5153, 88 p., http://dx.doi.org/10.3133/sir20165153. 20160812 Model archive created 20160814 Model archive updated based on Swanson, R.B. review of model archive 20160912 Model archive updated based on Delin, G.N. review of the model archive 20161122 Model archive updated based on Watt, M.K. peer review of the model archive and metadata 20161128 Model archive approved by Swanson, R.B. 20161128 Model archive updated with final information for running the model described in SIR 2016-5153 and uploaded to the web SIR2016-5153/ DESCRIPTION: ----------- The underlying directories contain all of the input and output files for a modified version of the soil-water-balance (SWB) model and sequential groundwater flow model for the Northern High Plains aquifer (http://dx.doi.org/10.3133/sir20165153). The modified SWB source code (Westenbroek and others, 2010) and MODFLOW-NWT (v 1.0.9)(Niswonger and others, 2011) source code for the versions of the software used to run the models are also provided. Descriptions of the data in each subdirectory are given to facilitate understanding of this data release. Longer files descriptions are provided for select files to provide additional information. Support is provided for correcting errors in the data release and clarification of the modeling conducted by the U.S. Geological Survey. Users are encouraged to review the model documentation report (http://dx.doi.org/10.3133/sir20165153) to understand the purpose, construction, and limitations of this model. System requirements: -------------------- The models contained in this data release were run using the MODFLOW-NWT_64.exe executable in the bin zip file in this data release. MODFLOW-NWT_64.exe was compiled using the Intel(R) Visual Fortran 64-bit compiler (version 14.0.0092.11) for Windows and the Visual C++ 2012 compiler. The models requires approximately 4 MB of available Random Access Memory (RAM). The models have been run successfully on computers running the following Windows operating systems (OS): o 64-bit Windows 7 OS (Service Pack 1) The source code has also been successfully compiled using the GFortran compiler and run on computers using the Mac OS X Mavericks (10.9) and SUSE Linux operating systems. Reconstructing the data release from the online data release files: ------------------------------------------------------------- This data release is available from: http://dx.doi.org/10.5066/F7JS9NKD The models will run successfully only if the original directory structure is correctly restored. The original directory structure is: SIR2016-5153/ readme.txt modelgeoref.txt ancillary/ ancillary/bin/ ancillary/SWB/climate/precip/ ancillary/SWB/climate/temp/max/ ancillary/SWB/climate/temp/min/ ancillary/SWB/externalfiles/ ancillary/SWB/images/ ancillary/SWB/input/ ancillary/SWB/output/ ancillary/SWB/std_input/ bin/ georef/ model/ model/externalfiles/ model/Modflow.1940_2009/ model/Modflow.Pre1940/ output/ output/Modflow.1940_2009/ output/Modflow.Pre1940/ source/ source/MODFLOW-NWT_1.0.9/ source/SWB/ The data release is broken into several pieces to reduce the likelihood of timeouts during download. Small files (readme.txt and modelgeoref.txt) are available as uncompressed files and should be in the directory SIR2016-5153/. The method to assemble the model files is: (1) Create the directory SIR2016-5153/. (2) Download the files for this data release into directory SIR2016-5153/. (3) From directory SIR2016-5153/, unzip the ancillary_SWB.zip file to set up the /SIR2016-5153/ancillary/ subdirectories. (4) Place the zip files into the following directories: ===zip file name==== ===Final designated directory== ancillary_SWB.zip /SIR2016-5153/ (UNZIP THIS FILE FIRST, it will make the ancillary subdirectories) ancillary_SWB_bin.zip /SIR2016-5153/ancillary/SWB/bin ancillary_SWB_climate_precip.zip /SIR2016-5153/ancillary/SWB/climate/precip ancillary_SWB_climate_temp_max.zip /SIR2016-5153/ancillary/SWB/climate/temp/max ancillary_SWB_climate_temp_min.zip /SIR2016-5153/ancillary/SWB/climate/temp/min ancillary_SWB_externalfiles.zip /SIR2016-5153/ancillary/SWB/externalfiles ancillary_SWB_images.zip /SIR2016-5153/ancillary/SWB/images ancillary_SWB_input.zip /SIR2016-5153/ancillary/SWB/input ancillary_SWB_output.zip /SIR2016-5153/ancillary/SWB/output ancillary_SWB_std_input.zip /SIR2016-5153/ancillary/SWB/std_input bin.zip /SIR2016-5153/ georef.zip /SIR2016-5153/ model.zip /SIR2016-5153/ output.zip /SIR2016-5153/ source.zip /SIR2016-5153/ doi10.5066_F7JS9NKD_webrelease.zip /SIR2016-5153/ (5) Uncompress each zip file in the final designated directories. This will put the zip file contents into the correct subdirectories. (6) Delete the zip files. All the files from the zip files are described in the "Files" section of this document. Running the model(s): --------------------- The models can be run by opening a command line/terminal window, changing the directory to the appropriate directory, and typing the name of the appropriate bat file. The SWB model is run from the command line. To run the SWB model, change the directory to the ancillary/SWB subdirectory and enter: run_NHP_SWB_from_ancillaryDir.bat The SWB executables are in the ancillary/SWB/bin subdirectory. The runtime for the SWB model can be about 24 hours. The output from the SWB model will be created in the ancillary/SWB/output subdirectory. The predevelopment period model is run from the command line. To run the predevelopment period model, change the directory to the model/Modflow.Pre1940/ subdirectory and enter: runModflow_Pre1940.bat The model program executable is in the bin subdirectory. The runtime for the predevelopment model is about 30 minutes. The output files from the predevelopment period model will be created in the output/Modflow.Pre1940 subdirectory. The development period model is run from the command line. To run the model, change the directory to the Modflow.1940_2009/ subdirectory and enter:. runModflow_1940_2009.bat. The model program executable is in the bin subdirectory. The runtime for the development model is about 4 hours. The output files from the development period model will be created in the output/Modflow.1940_2009 subdirectory Files: ----- The files in each directory are described below, by directory and subdirectory: A. \SIR2016-5153\ 1. modelgeoref.txt: ASCII file with the four corners of the model domain. Model data files are in the NAD 1983 Albers projection, in feet. Both latitude and longitude and Albers coordinates are provided. Coordinates of the upper left hand corner of the MODFLOW model coordinates represent row 1, column 1. Neither the SWB nor MODFLOW models are rotated. 2. readme.txt: This file. The readme file documents the structure, directories and files, and instructions on how to run the model for this data release. B. \SIR2016-5153\ancillary\SWB\ directory 1. NHPswb20130903.ctl – control file used to specify the SWB options for running the program (swb.exe) and input and output files. 2. run_NHP_SWB.bat – batch file used to execute the SWB program using control file NHPswb20130903.ctl. This bat file also deletes non-essential output files. 3. SWB_LOGFILE_YYYYMMDD_HHMMSS.txt – log file written by SWB when the program is executed 4. A number of non-essential output files generated by SWB and placed in the .\ancillary\SWB\ or .\ancillary\SWB\output directories. These files can be used in model development, but were not used for this model. These files are deleted by the run_NHP_SWB.bat file. C. \SIR2016-5153\ancillary\SWB\bin\ directory 1. swb.exe – the modified SWB executable used for this model, code was compiled on: Aug 15 2013 13:20:47. The published SWB code (Westenbroek and others, 2010) was modified by Steve Westenbroek to estimate irrigation requirements using crop coefficients for early, peak, and late stages of growth (Allen and others, 1998). 2. swbread.exe –SWB required executable 3. swbstats.exe – SWB required executable D. \SIR2016-5153\ancillary\SWB\climate\ A subdirectory of input climate-related subdirectories and files. 1. precip a. ppt_YYYY_MM_DD.asc, daily precipitation data from 19390101 to 20091231, in inches 25,933 files (National Climatic Data Center, 2010). 2. temp a. max i. tmax_YYYY_MM_DD, daily maximum temperature data from 19390101 to 20091231, in degrees Fahrenheit, in 25,933 files (National Climatic Data Center, 2010). b. min i. tmin_ YYYY_MM_DD, daily minimum temperature data from 19390101 to 20091231, in degrees Fahrenheit, in 25,933 files (National Climatic Data Center, 2010) E. \SIR2016-5153\ancillary\SWB\externalfiles\ directory 1. gwirrgrid2.asc: A raster of the study area. The raster value is zero (0) in the modeled area if the part or the entire cell was irrigation using surface water in 2008. Otherwise the cell value is 1. This raster is used to zero out cells with SWB irrigation amounts to derive irrigation from groundwater and not surface water. 2. header.asc: This file is the contents of required six header lines for all ASCII-raster files. The file was used to convert grid output to a raster for display in a geographic information system (GIS). This is the same file as is in the \ancillary\SWB\input directory. 3. swbgwirrMC.dat: SWB monthly irrigation amount output from 1/1/1940 to 12/31/2009 as an average in feet per day, by season (irrigation and non-irrigation), and by year, for input to a process to create the file swbMC.wel, which is input to MODFLOW. There are 61,986,150 lines in the file for 69 years with 2 seasons each year. 4. swbMC.wel: Input to MODFLOW, 1,144,051 lines in file. This file is derived from files (a) swbgwirrMC.dat, which is the SWB calculated irrigation amount with groundwater, and (b) gwirrgrid2.asc, which is a raster of the study area with cells in the model area set to 0, if crops in that cell were irrigated with surface water in 2008. 5. swbrchMC.dat: SWB monthly recharge output from 1/1/1940 to 12/31/2009 as an average in feet per day, by season (irrigation and non-irrigation), and by year, for input to MODFLOW. 61,986,150 lines in file for 69 years with 2 seasons each year. 6. swbrchMC40s.dat: SWB monthly recharge output from 1/1/1940 to 12/31/1950 as an average in feet per day for input to MODFLOW. There are 449,175 lines in file. F. \SIR2016-5153\ancillary\SWB\images\ A required output subdirectory for SWB; the image subdirectory is not used with this SWB model. G. \SIR2016-5153\ancillary\SWB\input\ A subdirectory of input files for the SWB program. 1. awc.asc: An ASCII-raster of available soil water-capacity (AWC), in inches per foot of thickness for the upper 59 inches of soil. The AWC of soils in the High Plains was derived from the General Soil Map (STATSGO2) (U.S. Department of Agriculture, 2006). A figure showing the AWC for the entire High Plains area is Figure 14 in Stanton and others (2011). 2. flow_dir.asc: An ASCII-raster of surface-flow direction generated by this study with ArcGIS from digital elevation models of the model area. Flow-direction values (1, 2, 4, 8, 16, 32, 64, 128) are described in Westenbroek and others (2010). 3. header.asc: This file is the contents of required six header lines for all ASCII-raster files. The file was used to convert grid output to a raster for display in a geographic information system (GIS). This is the same file as is in the externalfiles directory. 4. hgwinact.asc: An ASCII -raster of soil hydrologic group, with values of 1-4 representing NRCS groups A-D (U.S. Department of Agriculture, 2006) 5. LU_YYYY.asc, where YYYY is 1939 to 2009: An ASCII-integer raster of land use codes, including agricultural, urban, forest, and grassland for the study area from 1939 to 2009 (Multi-Resolution Land Characteristics Consortium, 2001; Houston and others, 2013). The land-use classifications follow Dripps (2003) the modified Anderson Level II classification scheme. 6. routfrac100.asc: This file can be used by SWB to specify that the model should route only a percentage of the runoff because of a large number of depressions such as ditches or potholes. For this SWB model, the cell contents are equal to 1 for all cells, meaning depressions are not a factor in this study area. H. \SIR2016-5153\ancillary\SWB\output\annual\ directory (284 files) 1. swb__IRRIGATION_AMOUNT_YYYY_MEAN.asc, where YYYY is from 1939 to 2009 (71 files) 2. swb__IRRIGATION_AMOUNT_YYYY_SUM.asc, where YYYY is from 1939 to 2009 (71 files) 3. swb__RECHARGE_YYYY_MEAN.asc, where YYYY is from 1939 to 2009, (71 files) 4. swb__RECHARGE_YYYY_SUM.asc, where YYYY is from 1939 to 2009, (71 files) I. .\ancillary\SWB\output\daily\ directory, this directory is required for SWB to run but is not populated for this model (0 files). J. \SIR2016-5153\ancillary\SWB\output\future\ directory (144 files). This directory contains the ending soil moisture and snow cover values for each year. For this model, 1. final_pct_sm_1939.asc is the final percent soil moisture for 1939 (1 file) 2. final_snow_cover_1939.asc is the final snow cover for 1939 (1 file) 3. swb_future_final_pct_sm_YYYY.asc, where YYYY is from 1939 to 2009 (71 files) 4. swb_future_final_snow_cover_YYYY.asc, where YYYY is from 1939 to 2009 (71 files) K. \SIR2016-5153\ancillary\SWB\output\monthly\ directory (3,408 files) 1. swb__IRRIGATION_AMOUNT_YYYY_MM_MEAN.asc is simulated mean irrigation by year and month, with yyyy corresponding to years 1939-2009 and mm corresponding to months 1-12 (852 files). 2. swb__IRRIGATION_AMOUNT_YYYY_MM_SUM.asc is the sum of simulated irrigation by year and month, with yyyy corresponding to years 1939-2009 and mm corresponding to months 1-12 (852 files). 3. swb__RECHARGE_YYYY_MM_MEAN.asc is simulated mean recharge by year and month, with yyyy corresponding to years 1939-2009 and mm corresponding to months 1-12 (852 files). 4. swb__RECHARGE_YYYY_MM_SUM.asc is the sum of simulated recharge by year and month, with yyyy corresponding to years 1939-2009 and mm corresponding to months 1-12 (852 files). L. \SIR2016-5153\ancillary\SWB\std_input\ A subdirectory of input files for the SWB program 1. LUlookup_03sep13.txt: The land-use lookup table required by the SWB program. The table entries are described in table 8 (Westenbroek and others, 2010). The landuse-lookup table allows the user to specify curve numbers, maximum recharge rates, and root-zone depths for each soil type within a given land-use type. In addition, the precipitation interception amount can be specified for each land-use type. The Natural Resources Conservation Service (NRCS) runoff-curve number for estimating the potential for surface runoff, plant interception values, and root-zone depth, were obtained from the Thornthwaite and Mather (1957), Cronshey and others (1986), USDA National Engineering Handbook (U.S. Dept. of Agriculture, 2004), Kranz and others (2008), and Stanton and others (2013). 2. IRRIGATION_LU__SMW_13NOV2012.txt: The irrigation land-use lookup table used in the modified SWB program. Since from the 1950s to present (2016), for many areas that overly the High Plains aquifer, irrigation water has been a substantial source of soil moisture, SWB code was modified (Westenbroek, written commun., 2013) to include irrigation water in the analysis by “allowing irrigation to maintain soil moisture in irrigated agricultural areas (Brown and others, 2008; Multi-Resolution Land Characteristics Consortium, 2001) above a minimum level during the growing season. The volume of water necessary to maintain that level of soil moisture was assumed to be the volume of water entering the soil profile from irrigation, and was calculated as equal to the part of crop demand beyond that available from infiltrated precipitation plus stored soil water above the specified minimum level. Some parts of the High Plains aquifer area were irrigated in the 1940s, but those areas composed a small percentage of the High Plains area (McGuire and others, 2003); therefore, irrigation water was not applied to the simulation during the 1940 (Stanton and others, 2013).” The code values in this table are derived from Stegman (1988) and Allen and others (2006). 3. soil-moisture-retention-extended.grd: ThornThwaite-Mather soil-moisture-retention table, which related the accumulated potential water loss to the amount of soil moisture retained over a range of soil-water capacities; this table is provided with the SWB program (Westenbroek and others, 2010). M. \SIR2016-5153\bin\ directory for the MODFLOW-NWT executables. The SWB executables are in the \ancillary\SWB\bin directory. 1. mod2obs.exe: Program used by PEST (Doherty, 2003 and 2005) to report simulated versus observed head values. 2. MODFLOW-NWT_64.exe: MODFLOW-NWT executable used for this simulation. N. \SIR2016-5153\georef\ directory. This directory contains a shapefile defining the active and inactive model areas. 1. SIR2016_5153.shp: GIS shape file of the NHP MODFLOW model boundary. The Area attribute defines the active and inactive model areas. O. \SIR2016-5153\model\externalfiles\ directory 1. aqb08aug13.asc: Input to discretization package, aquifer base. 2. default.prj: Default projection for NHP spatial data sets. 3. elevftapr11.asc: Input to discretization package, top of layer 1. 4. etflag3.asc: Input to the evapotranspiration package, evapotranspirationextinction depth array. 5. etsurf.asc: Input to the evaportranspiation package, evapotranspirationsurface array. 6. ibv4_08aug13.asc: MODFLOW i-bound array. 7. mod.upw: MODFLOW2000 Layer Property Flow (LPF) Package modified to UPW, calls the nhpPPintrp._kx array. 8. nhp2-1.spc: Grid specification file, contains model specifications to plot head locations, referred to by mod2obs_DEV2.in. 9. nhp3-2.hfb: MODFLOW-NWT Input file, boundary flows. 10. nhppd3-4.nwt: MODFLOW-NWT Input File modified from Test Problem 3 for UPW Package and NWT Solver 11. nhpPPintrp._kx: Horizontal hydraulic conductivity used in both the predevelopment and development periods. Hydraulic conductivity determined by PEST pilot points (Doherty, 2003 and 2005), and called from the MODFLOW .upw file P. \SIR2016-5153\model\Modflow_Pre1940\ directory 1. annpevfl.asc: Input to the evapotranspiration package for the predevelopment period, the evapotranspiration maximum array. 2. mod2obs_predev_PE.in: Input file for predevelopment mod2obs program, which reads in head observations and locations to PEST (Doherty,2009) 3. nhppd5-1.bas: MODFLOW basic package file for the predevelopment model. Input files are ibv4_08aug13.asc and stwl08aug13.asc. 4. nhppd5-1.dis: MODFLOW discretization file for the predevelopment period model. Input files are elevftapr11.asc and aqb08aug13.asc. 5. nhppd5-1.evt: MODFLOW evapotranspiration package for the predevelopment period model. Input files are etsurf.asc, annpevfl.asc, and etflag3.asc, 6. nhppd5-1.gag: MODFLOW gage file for the predevelopment period model 7. nhppd5-1.rch: MODFLOW recharge file for predevelopment period model. Inputs are pdrechbas.asc and pdsp#all.asc, where # is the values 2 through 8. 8. nhppd5-1_20oct14.drn: MODFLOW drain file for predevelopment period model. This file was created using GIS. 9. nhppd5-2.nam: Predevelopment name file, contains a list of all packages used in the MODFLOW simulation and the unit numbers MODFLOW calls to run the packages. 10. nhppdc4-1.oc: MODFLOW output control file for the predevelopment period model. 11. pdpecrdSEP11t.txt: Bore coordinates file. 12. pdrechbas.asc: Predevelopment recharge after calibration by PEST (Doherty, 2005). 13. pdSFR25mar13.sfr: Streamflow routing, created using GIS. 14. pdsp#all.asc: Canal recharge in stress period, where # is 2 to 8. 15. pdwlTGTsep11.txt: Bore coordinates file. 16. runModflow_Pre1940.bat: Bat file to run MODFLOW for predevelopment. 17. settings.fig: This is a MODFLOW required file and used by PEST utilities (Doherty, 2005 and 2009). 18. stwl08aug13.asc: Input file to basic package. 19. sy28aug12.txt: Aquifer specific yield, file is called by the MODFLOW UPW package. 20. usgs.model.reference: USGS required model file to register model in time and space. Q. \SIR2016-5153\model\Modflow_1940_2009\ directory 1. default.prj: Default project projection, used by python scripts to make spatial data sets. 2. devSFR20sep13.sfr: Streamflow routing, created using GIS. 3. drtne_mnw2_12sep12.mnw2: Input to MODFLOW: Municipal pumping in the study area for the development period. 4. ghb_11sept12m2.ghb: MODFLOW general head boundary package. 5. irrpevfl.asc: Input to the evapotranspiration package for development period, the evapotranspiration maximum array during irrigation season. 6. mod2obs_DEV2.in: MODS2OBS input, specifies input files nhp2-1.spc, wltrgts_crd06sep12.txt, wltrgts_06sep12.txt; output is nhpdev3-1.hds and dev_hds.out. 7. modrch.dat: Recharge file input to MODFLOW, created using SWB output and other files. 8. nhpdev3-1.bas: MODFLOW basic package file for the development model. References ibv4_08aug13.asc. 9. nhpdev3-1.dis: MODFLOW discretization file for the development period model. Input files are elevftapr11.asc and aqb08aug13.asc. 10. nhpdev3-1.evt: MODFLOW evapotranspiration package for the predevelopment period model. Input files are etsurf.asc, irrpevfl.asc, and etflag3.asc. 11. nhpdev3-1.gag: MODFLOW gage file for the development period model. 12. nhpdev3-1.oc: MODFLOW output control file for the development period model. 13. nhpdev3-1.rch: MODFLOW recharge file for development period model, input is unit 17, file modrch.dat. 14. nhpdev3-1_20oct14.drn: MODFLOW drain file for development period model. This file was created using GIS. 15. nhpdev3-2.nam: Development period name file, contains a list of all packages used in the MODFLOW simulation and the unit numbers MODFLOW calls to run the package. 16. nonpevfl.asc: Input to the evapotranspiration package for the development period. This is the evapotranspiration maximum array during non-irrigation season. 17. runModflow_1940_2009.bat: Bat file to run MODFLOW for the development period. 18. settings.fig: This is a MODFLOW required file and used by PEST utilities (Doherty, 2005 and 2009). 19. swbMC.wel: MODFLOW well package, calculated irrigation withdrawals by cell. 20. sy28aug12.txt: Aquifer specific yield, file is called by the MODFLOW UPW package. 21. wltrgts_06sep12.txt: Input to mods2obs through mod2obs_DEV2.in. 22. wltrgts_crd06sep12.txt: Input to mods2obs through mod2obs_DEV2.in. 23. usgs.model.reference: USGS required model file to register model in time and space. R. \SIR2016-5153\output\output.Modflow_Pre1940\ directory 1. Twenty-six files of streamflow, name #######.sg, where ####### is the gaging station number. 2. nhppd5-1.cbb: MODFLOW output cell-by-cell flow package file for the predevelopment period model 3. nhppd5-1.ddn: MODFLOW output drawdown file for the predevelopment period model 4. nhppd5-1.hds: MODFLOW output file of simulated groundwater heads for the predevelopment period 5. nhppd5-1.lst: MODFLOW output list file from the predevelopment period model. Contains water budget summaries for stress periods designated by the output control file 6. pdlong_PE_hds_out.smp: This file is generated by Mod2obs and consists of the simulated and measured groundwater levels relevant to the pre-1940 model. File pdpecrdSEP11t.txt has all the observation locations for this set. 7. sfrpd.out : This file is generated by the SFR package and contains a cell-by-cell accounting of all the flows simulated by the SFR package. File is only used during model development. S. \SIR2016-5153\output\output.Modflow_1940_2009\ directory 1. Ninety-one files of streamflow, name #######d.sg, where ####### is the gaging station number. 2. nhpdev3-1.cbb: MODFLOW output cell-by-cell flow package file for the development period model. 3. nhpdev3-1.ddn: MODFLOW output drawdown file for the development period model. 4. nhpdev3-1.hds: MODFLOW output file of simulated groundwater heads for the development period. 5. nhpdev3-1.lst: MODFLOW output file of simulated groundwater heads for the development period. 6. dev_hds.out: This is equivalent to the mod2obs output file but in this case is for the 1940—2009 period; contains all the simulated and measured groundwater levels. The file wltrgts_crd06sep12.txt which has all the observation locations 7. nhppd5-1.hds: MODFLOW output file of simulated groundwater heads for the predevelopment period, input to MODFLOW for the development period. 8. reducedQ.txt: wells with reduced pumping by stress period. 9. sfrdev.out: This file is generated by the SFR package and contains a cell-by-cell accounting of all the flows simulated by the SFR package. File is only used during model development. T. \SIR2016-5153\model\source\SWB directory: 1. FORTRAN_SWB_4_NHPmodel.zip: Fortran source code for modified SWB code used for this model 2. SWB_SourceCode_fromGITHUB: a GITHUB collection of the source files for the modified SWB model code. U. \SIR2016-5153\model\source\MODFLOW directory 1. MODFLOW-NWT_1.0.9.zip: The MODFLOW-NWT source code. V. \SIR2016-5153\webrelease directory zip files for web release. 1. SIR2016-5153Thumbnail.jpg: An image of the model area, which is in the metadata. 2. sir2016-5153.xml: The metadata for this data release. References Allen, R.G., Pereira, L.S., Raes, Dirk, and Smith, Martin, 1998, Crop evapotranspiration—Guidelines for computing crop water requirements: Rome, FAO Irrigation and Drainage paper 56, 300 p., accessed November 9, 2010, at http://www.fao.org/docrep/x0490e/x0490e00.htm#Contents. This document has a Feb 2006 errata sheet. Brown, J.F.; Maxwell, Susan; Pervez, Shahriar; Wardlow, Brian; and Callahan, Karin, 2008, National irrigated lands mapping via an automated remote sensing based methodology: Proceedings of the 88th Annual Meeting of the American Meteorological Association, 22nd Conference on Hydrology, 2008, New Orleans, La., No. 12.5, data accessed on December 6, 2010, at http://earlywarning.usgs.gov/USirrigation/. Cronshey, R.G., McCuen, R.H., Miller, Norman, Rawls, Walter, Robbins, Sam, and Woodward, Don, 1986, Urban hydrology for small watersheds—TR-55 (2nd ed.): Washington, D.C., U.S. Dept. of Agriculture, Soil Conservation Service, Engineering Division, Technical Release 55, 164 p. Doherty, John, 2003, Ground water model calibration using pilot points and regularization: Groundwater, v. 41, no. 2, p. 170–177. [Also available at http://dx.doi.org/10.1111/j.1745-6584.2003.tb02580.x.]. Doherty, John, 2005, PEST, model independent parameter estimation—User manual (5th ed.): Brisbane, Australia, Watermark Numerical Computing, accessed July 26, 2011, at http://pesthomepage.org/. Doherty, John, 2009, Groundwater data utilities—Part B: Program descriptions: Brisbane, Australia, Watermark Numerical Computing, accessed April 3, 2014, at http://pesthomepage.org/. Dripps, W.R., 2003, The spatial and temporal variability of groundwater recharge within the Trout Lake basin of northern Wisconsin: Madison, Wis., University of Wisconsin Ph.D. dissertation, 231 p. Houston, N.A., Gonzales-Bradford, S.L., Flynn, A.T., Qi, S.L., Peterson, S.M., Stanton, J.S., Ryter, D.W., Sohl, T.L., and Senay, G.B., 2013, Geodatabase compilation of hydrogeologic, remote sensing, and water-budget-component data for the High Plains aquifer, 2011: U.S. Geological Survey Data Series 777, 12 p., http://pubs.usgs.gov/ds/777/. Kranz, W.L., Irmak, Suat, Donk, S.J. van, Yonts, C.D., and Martin, D.L., 2008, Irrigation management for corn: University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources, NebGuide G1850, 4 p. [Also available at http://extensionpublications.unl.edu/assets/html/g1850/build/g1850.htm.] Multi-Resolution Land Characteristics Consortium (MRLC), 2001, National Land Cover Database: U.S. Geological Survey, accessed August 22, 2011, at http://www.mrlc.gov/nlcd01_data.php. National Climatic Data Center, 2010, Locate weather observation station record: Asheville, N.C., National Climatic Data Center, data accessed June 15, 2010, at http://www.ncdc.noaa.gov/oa/climate/stationlocator.html. Niswonger, R.G., Panday, Sorab, and Ibaraki, Motomu, 2011, MODFLOW-NWT, A Newton formulation for MODFLOW-2005: U.S. Geological Survey Techniques and Methods 6-A37, 44 p., also available at http://pubs.usgs.gov/tm/tm6a37/. Qi, S.L., 2009, Digital map of aquifer boundary for the High Plains aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: U.S. Geological Survey Data Series 543, http://water.usgs.gov/lookup/getspatial?ds543. Stanton, J.S., Qi, S.L., Ryter, D.W., Falk, S.E., Houston, N.A., Peterson, S.M., Westenbroek, S.M., and Christenson, S.C., 2011, Selected approaches to estimate water-budget components of the High Plains, 1940 through 1949 and 2000 through 2009: U.S. Geological Survey Scientific Investigations Report 2011–5183, 79 p., available at http://pubs.usgs.gov/sir/2011/5183/. Stanton, J. S., Ryter, D. W. and Peterson, S. M., 2013, Effects of Linking a Soil-Water-Balance Model with a Groundwater-Flow Model. Groundwater, 51: 613–622. doi:10.1111/j.1745-6584.2012.01000.x Stegman, E.C., 1988, Corn crop curve comparisons for the central and northern plains of the U.S.: Applied Engineering in Agriculture, v. 4, no. 3, p. 226–233. Thornthwaite, C.W., and Mather, J.R., 1957, Instructions and tables for computing potential evapotranspiration and the water balance: Drexel Inst. of Tech. (Philadelphia) Publications in Climatology, v. 10, no. 3, p. 185–311. Westenbroek, S.M., Kelson, V.A., Dripps, W.R., Hunt, R.J., and Bradbury, K.R., 2010, SWB—A modified Thornthwaite-Mather Soil-Water-Balance code for estimating groundwater recharge: U.S. Geological Survey Techniques and Methods, book 6, chap. A31, 60 p., accessed December 20, 2010, at http://pubs.usgs.gov/tm/tm6-a31/. U.S. Department of Agriculture, 2004, Hydrology: USDA-NRCS National Engineering Handbook, Part 630, Chapter 9: Washington, D.C., U.S. Department of Agriculture, 14 p. U.S. Department of Agriculture, 2006, United States General Soil Map (STATSGO2): Digital data, accessed October 13, 2009, at http://www.soils.usda.gov/survey/geography/statsgo/.