Joseph A. Hevesi Wesley Henson Randy T. Hanson Marisa M. Earll Deidre M. Herbert Elizabeth R. Jachens 20250408 tabular digital data U.S. Geological Survey data release https://doi.org/10.5066/P9FJAWC4 Joseph A. Hevesi Wesley Henson Randy T. Hanson Marisa M. Earll Deidre M. Herbert Elizabeth R. Jachens 2025 publication Reston, VA, USA U.S. Geological Survey https://doi.org/10.3133/sir20255009 This model archive contains the datasets, procedures, and necessary program code used to describe the Salinas Valley Watershed Model (SVWM). The SVWM simulates the daily historical water balance and hydrologic conditions for the Salinas Valley study area including the many un-gaged tributary subdrainages in the rugged and mountainous upland areas surrounding flat-lying valley lowlands coinciding with developed areas including croplands irrigated with groundwater. The SVWM simulates the natural hydrologic system for the entire Salinas Valley watershed and adjacent coastal basins, excluding anthropogenic components such as pumping, diversions, irrigation, and reservoir operations, for the 70 years beginning October 1, 1948, and ending September 30, 2022. The SVWM uses two modeling applications; the Hydrologic Simulation Program – Fortran (HSPF, version 12.4; U.S. Environmental Protection Agency, 2000) to simulate the natural hydrologic system (Bicknell and others., 2005) and the Basin Characterization Model (BCM; Flint and others, 2021) to develop spatially distributed, historical climate inputs for HSPF. The HSPF application simulates the daily surface water and shallow subsurface water storage and flow processes, including interception storage and evaporation on vegetation, surface retention storage and evaporation, pervious land soil water storage and evapotranspiration, runoff from impervious and pervious land areas, streamflow, recharge from pervious land areas, and recharge from streamflow seepage. Climate inputs developed using the BCM are daily precipitation, daily maximum and minimum air temperature, and daily potential evapotranspiration (PET) (Hevesi and others, 2022). SVWM parameters were estimated using geospatial data and then adjusted by trial-and-error fitting of simulated daily streamflow to long-term records of observed streamflow at 29 U.S. Geological Survey stream gages (U.S. Geological Survey, 2016) and to estimated daily surface water inflows to Nacimiento and San Antonio Reservoirs (Henson and others, 2022a). The trial-and-error calibration provided a good match between simulated and observed daily, monthly, mean-monthly, and annual streamflow. The simulated output components from the SVWM include evapotranspiration, land area runoff (overland flow, interflow, baseflow), recharge, and groundwater recharge for the 690 HRUs, as well as streamflow and stream seepage losses for the 690 stream reaches connecting the HRUs. This model archive presents the data were used as input files as well as the code to run the Salinas Valley Watershed Model (SVWM). This model was run using HSPF version 12.4. This version of the code is no longer supported or publicly available from the U.S. Environmental Protection Agency (EPA). Users can download the latest version of the code from https://www.epa.gov/hydrowq/basins-download-and-installation (U.S. Environmental Protection Agency, 2024). Please be aware that using the later versions of the code, and not the code used to produce the output archived with this data release, may result in slightly different output. For further information about BASINS data or metadata, please email ceam@epa.gov. 19481001 20220930 ground condition Complete None planned -121.8672 -119.9315 36.9264 35.1010 ISO 19115 Topic Category environment USGS Thesaurus atmospheric and climatic processes precipitation (atmospheric) air temperature evaporation watershed management surface water (non-marine) streamflow mathematical modeling runoff groundwater and surface-water interaction USGS Metadata Identifier USGS:6538101fd34ee4b6e05bba1e Common Geographic Areas California Salinas Monterey None Salinas Valley 180-Foot Aquifer 400-Foot Aquifer None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Wesley Henson U.S. Geological Survey, SOUTHWEST REGION Hydrologist mailing address

4165 Spruance Road

San Diego CA 92101-0821 US 619-225-6170 619-225-6101 whenson@usgs.gov ArcGIS ArcMap 10.8.1, Notepad ++, HSPF version 12.4 (See "Supplemental Information" section for more details), SARA Utility Tool U.S. Environmental Protection Agency (EPA) 2024 Basins 4.5 & HSPF 12.5 application/service Download available for the installer for HSPF 12.5 Plugin. For further information about BASINS data or metadata please "ceam@epa.gov" https://www.epa.gov/hydrowq/basins-download-and-installation Bicknell, B. R. Imhoff, J. C. Kittle Jr, J. L. Jobes, T. H. Donigian Jr, A. S. 2005 publication Athens, GA U.S. Environmental Protection Agency (EPA) https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1019SW0.TXT United States Environmental Protection Agency (EPA) 2000 publication Office of Water, EPA-823-R00-012, July 2000, 34p. https://www.epa.gov/sites/default/files/2015-08/documents/2000_08_14_basins_tecnote6.pdf Lorraine E. Flint Alan L. Flint Michelle A. Stern 2021 publication n/a US Geological Survey https://doi.org/10.3133/tm6H1 Wesley Henson Joseph A. Hevesi Randall T. Hanson Daniel Bittner Deidre M. Herbert Elizabeth R Jachens 2022 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/P93COXL6 Joseph A. Hevesi Wesley Henson Randall T. Hanson Michelle A. Stern Elizabeth R. Jachens 2022 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/P942J2BC U.S. Geological Survey (USGS) 2016 publication Date accessed 21 November 2023 https://doi.org/10.5066/F7P55KJN No formal tests were conducted No formal logical accuracy tests were conducted. Data were reviewed for consistency. See the data source for more information Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. See the data source for more information Bicknell, B. R. Imhoff, J. C. Kittle Jr, J. L. Jobes, T. H. Donigian Jr, A. S. 2005 tabular digital data U.S. Environmental Protection Agency, Athens, Ga. Digital and/or Hardcopy 2005 publication date Bicknell and others, 2005 HSPF reference documentation for version 12.2 Bicknell, B. R. Imhoff, J. C. Kittle Jr, J. L. Jobes, T. H. Donigian Jr, A. S. 2001 tabular digital data 845 p. Digital and/or Hardcopy 2001 publication date Bicknell and others, 2001 HSPF reference documentation for version 12 Daly, C. Gibson, W. P. Doggett, M. Smith, J. Taylor, G. 2004 tabular digital data Proc., 14th AMS Conf. on Applied Climatology, 84th AMS Annual Meeting Combined Preprints, Amer. Meteorological Soc., Seattle, WA. https://prism.oregonstate.edu/documents/pubs/2004appclim_monthlyMaps_daly.pdf Digital and/or Hardcopy 2004 publication date Daly and others, 2004 Parameter-elevation Regression on Independent Slopes Model (PRISM) Daly, C. Neilson, R. P. Phillips, D. L. 1994 tabular digital data Journal of Applied Meteorology and Climatology, 33(2), 140–158. https://doi.org/10.1175/1520-0450(1994)033%3C0140:ASTMFM%3E2.0.CO;2 Digital and/or Hardcopy 1994 publication date Daly and others, 1994 Parameter-elevation Regression on Independent Slopes Model (PRISM) California Department of Water Resources 2004 tabular digital data https://map.dfg.ca.gov/metadata/calw221_polygon_20131205_wm.html Digital and/or Hardcopy 2004 publication date California Department of Water Resources, 2004 watershed areas used to define and validate the model HRUs U.S. Environmental Protection Agency (EPA) 2000 tabular digital data Office of Water, EPA-823-R00-012, July 2000, 34p. https://www.epa.gov/sites/default/files/2015-08/documents/2000_08_14_basins_tecnote6.pdf Digital and/or Hardcopy 2000 publication date U.S. Environmental Protection Agency, 2000 PA Basins Technical Note 6 with model parameter definitions U.S. Environmental Protection Agency (EPA) 2023 tabular digital data Date accessed 21 November 2023 https://www.epa.gov/ceam/basins-framework-and-features Digital and/or Hardcopy 2023 publication date U.S. Environmental Protection Agency, 2023 WDMUtil program to manage WDM files Lorraine E. Flint Alan L. Flint Michelle A. Stern 2021 publication n/a US Geological Survey Associated data release: https://doi.org/10.5066/P9PT36UI. https://doi.org/10.3133/tm6H1 Digital and/or Hardcopy 2021 publication date Flint and others, 2021 PET calculation Wesley Henson Scott E. Boyce Howard Franklin Amy Woodrow Matthew N. Baillie Elizabeth R. Jachens 2022 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/P9CWNHN3 Digital and/or Hardcopy 2022 publication date Henson and others, 2022a reservoir inflows provided by Monterey County Water Resources Agency Wesley Henson Joseph A. Hevesi Randall T. Hanson Daniel Bittner Deidre M. Herbert Elizabeth R. Jachens 2022 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/P93COXL6 Digital and/or Hardcopy 2022 publication date Henson and others, 2022b surface water inflows and diversions for the Salinas Valley area Joseph A. Hevesi Wesley Henson Randall T. Hanson Michelle A. Stern Elizabeth R. Jachens 2022 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/P942J2BC Digital and/or Hardcopy 2022 publication date Hevesi and others, 2022 Climate data, adapted from Flint and others (2021) Nalder, I. A. Wein, R. W. 1998 tabular digital data Agricultural and Forest Meteorology, 92(4), 211–225. https://doi.org/10.1016/S0168-1923(98)00102-6 Digital and/or Hardcopy 1998 publication date Nalder and Wein, 1998 the Gradient-Inverse-Distance-Squared (GIDS) method to downscale and spatially interpolate gridded data to model area San Antonio River Authority (SARA) 2019 tabular digital data https://www.respec.com/product/modeling-optimization/sara-timeseries-utility/ Digital and/or Hardcopy 2019 publication date SARA, 2019 tool to ready binary files including WDM files Seaber, P. R. Kapinos, F. P. Knapp, G. L. 1987 tabular digital data (Vol. 2294, p. 1987). Washington, DC, USA: US Government Printing Office. Accessed on 20 September 2015. https://water.usgs.gov/GIS/huc.html Digital and/or Hardcopy 1987 publication date Seaber and others, 1987 water drainage divides based on hydrologic unit code 12 (HUC-12) boundaries U.S. Geological Survey (USGS) National Geospatial Program 2022 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/P9WFOBQI Digital and/or Hardcopy 2022 publication date U.S. Geological Survey, 2022 Watershed areas defining the Salinas Valley Watershed U.S. Geological Survey (USGS) 2023 tabular digital data https://www.sciencebase.gov/catalog/item/4f70aa71e4b058caae3f8de1 Digital and/or Hardcopy 2023 publication date U.S. Geological Survey, 2023 Digital Elevation Models (DEM) U.S. Geological Survey (USGS) 2016 tabular digital data Date accessed 21 November 2023 https://doi.org/10.5066/F7P55KJN Digital and/or Hardcopy 2016 publication date U.S. Geological Survey, 2016 National Water Information System (NWIS) streamflow observed values Development of the SVWM required (1) defining the model domain and discretization, (2) estimating the initial conditions, (3) creating the Watershed Data Management (WDM) file from climate input data, (4) creating the User Control Input (UCI) file, and (5) performing model calibration and evaluation. 1. Model Domain: The SVWM boundary was defined mostly by surface water drainage divides based on hydrologic unit code 12 (HUC-12) boundaries (Seaber and others, 1987), with minor modifications using NHD flowlines and flow directions based on calculated land surface slope using 10-meter (98.4 feet) resolution digital elevation data (U.S. Geological Survey, 2022; U.S. Geological Survey, 2023). A total of 35 complete or partial HUC-12 areas are included in the SVWM area, which is further delineated into 690 Hydrologic Response Units (HRUs; Henson and others, 2022b). The HRU is a basic homogenous model segment used to spatially partition and discretize the model domain. Each HRU represents a single pervious land area connected to a single stream reach. The HRU delineation was developed using irregular-polygon areas representing surface water sub-drainages that were defined using a combination of 10-meter (98-foot) digital elevation models (U.S. Geological Survey, 2023), the National Hydrography Dataset (NHD) streamlines and sub-drainage boundaries (U.S. Geological Survey, 2022) and Calwater version 2.2.1 watershed areas (California Department of Water Resources, 2004). Each HRUs is associated with an inflow point that connects the HRU to upstream catchments, except in a few cases where there are collector segments where a single inflow point is associated with two HRUs (Henson and others, 2022b). Seaber and others, 1987 U.S. Geological Survey, 2022 U.S. Geological Survey, 2023 California Department of Water Resources, 2004 Henson and others, 2022b 2022 2. Initial Conditions: The initial conditions include water contents for interception storage, retention storage, soil moisture (upper and lower zones), interflow storage, and active groundwater storage that were either set to zero or based on values defined in the HSPF manual (Bicknell and others, 2005). Bicknell and others, 2005 2022 3. Input Datasets: The input datasets to the SVWM included the climate parameters of precipitation, maximum and minimum air temperature), and potential evapotranspiration (PET) for the Salinas Valley study area. These datasets are provided by the Basin Characterization Model (BCM; Flint and others, 2021). The BCM applications use monthly climate data from the Parameter-elevation Regression on Independent Slopes Model (PRISM) (Daly and others, 1994, 2004), available daily climate records, and the Gradient-Inverse-Distance-Squared (GIDS) method (Nalder and Wein, 1998) to downscale and spatially interpolate climate data to a 270-meter (886-foot) grid covering the SVWM study area. The four 270-meter gridded climate inputs were area-weight averaged over the area of each HRU. Using a uniform hourly distribution, the four daily climate time series developed for each HRU were disaggregated into hourly time series, starting at one second after midnight, October 1, 1947, and ending at midnight, September 30, 2022. The 690 unique sets of hourly climate time-series inputs were compiled and stored in a single binary Watershed Data Management (WDM) file used by the HSPF code. Flint and others, 2021 Daly and others, 1994 Daly and others, 2004 Nalder and Wein, 1998 Hevesi and others, 2022 2022 4. Input Files: The HSPF code requires a User Control Input (UCI) file to specify model control options, the simulation period, model parameters, and input and output filenames needed to run a simulation. The UCI file is an ascii text file with a formatted, column-specified input structure. The model parameters are organized according to the modular structure of HSPF, with separate input groups used for simulating water flow and storage within pervious land (PERLND) areas, impervious land (IMPLND) areas, and the connected stream reach (RCHRES) network. Examples of PERLNDS are natural and developed land areas with soil coverage, while impervious developed land surfaces such as rooftops, roads, and parking lots are considered IMPLNDs. Parameters used to simulate water flow and storage in pervious land areas define spatially varying catchment properties throughout the SVWM and were the most important for representing the physical characteristics of the Salinas Valley study area. Initially, model parameters were defined using a combination of geospatial data and representative values from previous studies, including suggested values provided in the HSPF user manual (Bicknell and others, 2001; U.S. Environmental Protection Agency, 2000). Fifteen of the seventeen PERLND parameters were then adjusted and refined during the model calibration procedure. Parameters LZSN, INFILT, LSUR, KVARY, AGWRC, INFEXP, DEEPFR, BASETP, and AGWETP were scaled using geospatial data and calibrated as a set of unique values for each HRU. Monthly parameters INTERCEP, UZSN, MANNING, INTERFLW, IRC, and LZETPARM were scaled using geospatial data and calibrated for each HRU as a unique set of twelve monthly values. HSPF pervious land area (PERLND) parameters. Modified from U.S. Environmental Protection Agency (2000). Format [Name: Description (units)] o LZSN: Lower Zone Nominal Soil Moisture Storage. Representative of Soils, topography, and climate (inches) o INFILT: Index to Infiltration Capacity. Divides surface and subsurface flow. Representative of soils and land use (inches per hour; in/hr) o LSUR: Length of overland flow. Estimated using topography (feet) o SLSUR: Slope of overland flow plane. Estimated using topography, defined using digital elevation model and not modified during calibration (ft/ft) o KVARY: Variable groundwater recession. Used when the recession rate varies with GW levels. Representative of baseflow recession variation. Estimated using surficial geology (1/inches) o AGWRC: Baseflow recession coefficient. Estimated using surficial geology (none) o INFEXP: Exponent in infiltration equation. Usually default to 2.0. Representative of soil variability. Estimated using topography (none) o INFILD: Ratio of max/mean infiltration capacities. Representative of soil variability. Set to default value of 2.0 and not changed during calibration (none) o DEEPFR: Fraction of GW inflow to deep recharge. Accounts for subsurface losses. Representative of geology, recharge to groundwater that does not contribute to baseflow (none) o BASETP: Fraction of remaining ET from baseflow. Accounts for direct ET from riparian vegetation (none) o AGWETP: Fraction of remaining ET from groundwater available for baseflow. Accounts for ET from shallow groundwater including marshes and wetlands. Estimated using land use (none) o INTERCEP: Interception storage capacity. Representative of vegetation type and density, land use (inches) o UZSN: Upper zone nominal soil moisture storage. Accounts for near-surface retention. Representative of soil conditions, land use (inches) o MANNING: Manning’s n (roughness) for overland flow. Representative of Surface conditions, residue, etc. (none) o INTERFLW: Interflow inflow parameter. Representative of soils, topography, land cover (none) o IRC: Interflow recession parameter. Representative of Soils, topography, land cover (none) o LZETPARM: Lower zone ET parameter. Representative of Vegetation type/density, root depth (none) The HSPF code version used to develop the SVWM is limited to a maximum number of 1,000 model elements, with each PERLND, IMPLND, and RCHRES comprising separate model elements. The SVWM model discretization includes a total of 1,561 elements (the sum of 690 PERLNDs, 181 IMPLNDs, and 690 RCHRESs), exceeding the capacity of the HSPF code version used. To preserve the degree of spatial detail provided by the 1,561 model elements, the SVWM was divided into the two HSPF sub-model domains, the upper Salinas Valley sub-model (USVS) and the lower Salinas Valley sub-model (LSVS). The upper Salinas Valley sub-model has an area of 2,536 square miles containing 387 HRUs with 36 HRUs including IMPLNDs. The Lower Salinas Valley sub-model has an area of 1,992 square miles containing 303 HRUs with 69 HRUs including IMPLNDs. The Lower Salinas Valley sub-model is connected to the Upper Salinas Valley sub-model at the location of gage 19 (U.S. Geological Survey stream gage 11150500, Salinas River near Bradley; U.S. Geological Survey, 2016). The climate timeseries input data is formatted in a file with the “.wdm” extension, referred to as the WDM file. The WDM file is a binary file, created by the WDMUtil program (distribution with the BASIN project; U.S. Environmental Protection Agency, 2023 or downloaded separately from SARA, 2019) and can be read by programs including the SARA Utility Tool. The San Antonio River Authority (SARA) Timeseries Utility Tool supports the analysis and management of time-varying environmental data including listing, graphing, numerical processing, statistics generation, computing meteorological data, and saving in a WDM or text file (SARA, 2019). Bicknell and others, 2001 U.S. Environmental Protection Agency, 2000 U.S. Environmental Protection Agency, 2023 SARA, 2019 U.S. Geological Survey, 2016 2022 5. Model Calibration and Evaluation: The SVWM was calibrated by comparing simulated and observed streamflow, including data from 29 U.S. Geological Survey stream gauges (U.S. Geological Survey, 2016) and reservoir inflow data (Henson and others, 2022a). The SVWM was validated using streamflow records for five stream gages having streamflow records that were not included in the calibration procedure. U.S. Geological Survey, 2016 Henson and others, 2022a 2022 Vector G-polygon Lambert Conformal Conic 37.25 36.0 -119.0 0.0 6561666.667 1640416.667 coordinate pair 0.6096 0.6096 meters North_American_Datum_1983 GRS 1980 6378137.0 298.257222101 SVWM_Domains.7z Attribute Table Zip file containing the shapefile with model extent and definition of the Lower Salinas Valley and the Upper Salinas Valley Producer Defined FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Shape type. SV_DOMAIN Model Domain Producer Defined LSV Lower Salinas Valley Producer defined USV Upper Salinas Valley Producer defined Shape_Leng ESRI defined Polygon Length ESRI 2306668.92518 2468085.92518 Shape_Area ESRI defined Polygon Area ESRI 55215292762.6 70711618820.6 SVWM_subbasins.7z Attribute Table Zip file containing the shapefile of the ten (10) model sub-basins Producer Defined FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Shape type. SubbasinID Sub-basin abbreviation Producer Defined ARR Arroyo Seco Producer defined EST Estrella River Producer defined LOR San Lorenzo Creek Producer defined LSR Lower Salinas River Producer defined MCB Monterey Coastal Basins Producer defined MSR Middle Salinas River Producer defined NAC Nacimiento River Producer defined SAN San Antonio River Producer defined SRH Salinas River Headwaters Producer defined USR Upper Salinas River Producer defined Subbasin Sub-basin name Producer Defined Name of the sub-basin, corresponding with the sub-basin ID SVWM_subdrainages.7z Attribute Table Zip file containing the shapefile of the 28 model sub-drainages Producer Defined FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Shape type. SubDrain2 Sub-drainage name Producer Defined See the column SubDrain2a for the corresponding abbreviations SubDrain2a Sub-drainage abbreviation Producer Defined See the column SubDrain2 for the corresponding name LSV_tributary.7z Attribute Table Zip file containing the Shapefile of the Lower Salinas Valley model tributary drainages Producer Defined FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Shape type. SVIHM_inf4 Lower Salinas Valley tributary basins Producer Defined << empty cell >> Salinas Valley Integrated Model boundary, which is not a tributary basins to the Lower Salinas Valley Model Producer defined See the column TribID for the corresponding abbreviations TribID Lower Salinas Valley tributary basins corresponding abbreviations Producer Defined See the column SVIHM_inf4 for the corresponding tributary names SVWM_Simulation_wy1948-2022.7z This is a zip file of the model files. There is a ReadMe file, named "SVWM_ModelArchive_ReadMe.docx", inside this folder to describe the files and contents. Producer Defined There are five (5) zipped files included: 1,2,3, and 5, and 4 is the compressed model and associated ReadMe file. 1. LSV_tributary.7z 2. SVWM_subbasins.7z 3. SVWM_subdrainages.7z 4. SVWM_Simulation_wy1948-2022.7z 5. SVWM_domains.7z The attribute table fields are defined in the details of the Entity and Attribute Section. See the rest of this metadata file and the Readme file for more information. N/A GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Digital Data https://doi.org/10.5066/P9FJAWC4 None 20250408 Elizabeth R. Jachens U.S. Geological Survey, SOUTHWEST REGION Hydrologist mailing address

4165 Spruance Road

San Diego CA 92101-0821 US 6192256144 ejachens@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998