The hydrologic modeling approach used to predict functional flows relies on daily streamflow data from gages operated by the U.S. Geological Survey (USGS) in California. This dataset contains, for each of 219 gages, a collection of metrics computed on each water year for the period of record to and including Water Year 2016.

The dataset contain estimates of natural monthly streamflow for 135,118 stream segments in California, USA, from 1950 to 2012. Segments are identified per the medium resolution National Hydrography Dataset (NHD), Version 1. The dataset also contains observed monthly streamflows and estimates of natural monthly streamflows for 894 USGS stream gages in California, USA.

This data release contains trend results computed on the basis of modeled and observed daily streamflows at 502 reference gages across the conterminous U.S. from October 1, 1983 through September 30, 2016. Modeled daily streamflows were computed using the deterministic Precipitation Runoff Modeling System (PRMS), and five statistical techniques: Nearest-Neighbor Drainage Area Ratio (NNDAR), Map-Correlation Drainage Area Ratio (MCDAR), Ordinary Kriging of the logarithms of discharge per unit area (OKDAR), Nearest-Neighbor nonlinear spatial interpolation using flow duration curves (NNQPPQ), and Map-Correlation nonlinear spatial interpolation using flow duration curves (MCQPPQ). Observed daily streamflow data for the study gages were retrieved from the National Water Information System (NWIS). Study gages were selected from among Hydro-Climatic Data Network 2009 (HCDN-2009) gages in the GAGES-II dataset considered to be minimally affected by regulation, diversion, mining, or other anthropogenic activities. Results include trends in annual and monthly means, annual percentiles (1, 5, 10, 25, 50, 75, 90, 95, 99), annual 1-day high, 3-day high, and 7-day low, and annual snowmelt-related runoff timing for a subset of snowmelt dominated basins. Bias and volumetric efficiency statistics between observed and modeled streamflows also are provided.

This data release contains trend results computed on the basis of modeled and observed daily streamflows at 502 reference gages across the conterminous U.S. from October 1, 1983 through September 30, 2016. Modeled daily streamflows were computed using the deterministic Precipitation Runoff Modeling System (PRMS), and five statistical techniques: Nearest-Neighbor Drainage Area Ratio (NNDAR), Map-Correlation Drainage Area Ratio (MCDAR), Ordinary Kriging of the logarithms of discharge per unit area (OKDAR), Nearest-Neighbor nonlinear spatial interpolation using flow duration curves (NNQPPQ), and Map-Correlation nonlinear spatial interpolation using flow duration curves (MCQPPQ). Observed daily streamflow data for the study gages were retrieved from the National Water Information System (NWIS). Study gages were selected from among Hydro-Climatic Data Network 2009 (HCDN-2009) gages in the GAGES-II dataset considered to be minimally affected by regulation, diversion, mining, or other anthropogenic activities. Results include trends in annual and monthly means, annual percentiles (1, 5, 10, 25, 50, 75, 90, 95, 99), annual 1-day high, 3-day high, and 7-day low, and annual snowmelt-related runoff timing for a subset of snowmelt dominated basins. Bias and volumetric efficiency statistics between observed and modeled streamflows also are provided.

This report summarizes estimates of “natural” and “unimpaired” flows for all areas in the Central Valley tributary to the Sacramento – San Joaquin Delta (Delta) for the period spanning water years 1922-2014. A major objective of this report is to clarify the conceptual differences between natural and unimpaired flows. In spite of the Department’s previous attempts to distinguish between natural conditions and its calculation of theoretical unimpaired flows, unimpaired flow estimates have frequently been used as a surrogate measure of natural conditions, presumably because natural flow estimates were unavailable. This report contains the Department’s first published estimates of natural flows; these estimates are derived from complex simulation models and are based on published estimates of natural vegetation cover and associated evapotranspiration.

This report summarizes estimates of “natural” and “unimpaired” flows for all areas in the Central Valley tributary to the Sacramento – San Joaquin Delta (Delta) for the period spanning water years 1922-2014. A major objective of this report is to clarify the conceptual differences between natural and unimpaired flows. In spite of the Department’s previous attempts to distinguish between natural conditions and its calculation of theoretical unimpaired flows, unimpaired flow estimates have frequently been used as a surrogate measure of natural conditions, presumably because natural flow estimates were unavailable. This report contains the Department’s first published estimates of natural flows; these estimates are derived from complex simulation models and are based on published estimates of natural vegetation cover and associated evapotranspiration.

This data release includes data containing projections of unimpaired hydrology, reservoir storage, and downstream managed flows in the Sacramento River/San Joaquin River watershed, California for scenarios of future climate change generated for the CASCaDE2 project (Computational Assessments of Scenarios of Change for the Delta Ecosystem, phase 2). Code used to produce the data is also included. The dataset is produced using a multiple-model approach. First, downscaled global climate model outputs are used to drive an existing Variable Infiltration Capacity/Variable Infiltration Capacity Routing (VIC/RVIC) model of Sacramento/San Joaquin hydrology, resulting in projections of daily, unimpaired flows throughout the watershed. A management model, CASCaDE2-modified CalSim (C2-CalSim), uses these projections as inputs and produces monthly estimates of reservoir and other infrastructure operations and resulting downstream managed flows. The CASCaDE2 resampling algorithm (CRESPI), also uses the projected daily unimpaired flows, along with historical managed flows, to estimate the daily variability in managed flows throughout the watershed. The monthly and daily managed-flow estimates are combined in a way that preserves the multi-decadal variability and century-scale trends produced by the C2-CalSim model and the day-to-day variability produced by the CRESPI algorithm. The resulting data are analyzed and processed to produce tables, figures, and text for the associated publications. To reduce the data release's size, data from a given step in the analysis that are not used in a subsequent step have not been included in this data release. All code generated by the USGS to produce the data in this data release is also included. This includes all code to download and preprocess external data; to set up and control the RVIC model runs; to modify, set up, and control runs of the CalSim 2 model; to implement and run the CRESPI algorithm; to postprocess and analyze model outputs; and to produce published figures, tables and text that includes calculated values. A detailed README file is included with instructions for running the code, including how to obtain the external RVIC and CalSim 2 models.

This data release includes data containing projections of unimpaired hydrology, reservoir storage, and downstream managed flows in the Sacramento River/San Joaquin River watershed, California for scenarios of future climate change generated for the CASCaDE2 project (Computational Assessments of Scenarios of Change for the Delta Ecosystem, phase 2). Code used to produce the data is also included. The dataset is produced using a multiple-model approach. First, downscaled global climate model outputs are used to drive an existing Variable Infiltration Capacity/Variable Infiltration Capacity Routing (VIC/RVIC) model of Sacramento/San Joaquin hydrology, resulting in projections of daily, unimpaired flows throughout the watershed. A management model, CASCaDE2-modified CalSim (C2-CalSim), uses these projections as inputs and produces monthly estimates of reservoir and other infrastructure operations and resulting downstream managed flows. The CASCaDE2 resampling algorithm (CRESPI), also uses the projected daily unimpaired flows, along with historical managed flows, to estimate the daily variability in managed flows throughout the watershed. The monthly and daily managed-flow estimates are combined in a way that preserves the multi-decadal variability and century-scale trends produced by the C2-CalSim model and the day-to-day variability produced by the CRESPI algorithm. The resulting data are analyzed and processed to produce tables, figures, and text for the associated publications. To reduce the data release's size, data from a given step in the analysis that are not used in a subsequent step have not been included in this data release. All code generated by the USGS to produce the data in this data release is also included. This includes all code to download and preprocess external data; to set up and control the RVIC model runs; to modify, set up, and control runs of the CalSim 2 model; to implement and run the CRESPI algorithm; to postprocess and analyze model outputs; and to produce published figures, tables and text that includes calculated values. A detailed README file is included with instructions for running the code, including how to obtain the external RVIC and CalSim 2 models.

This data release documents the datasets and procedures used to update the Los Angeles Basin Watershed Model (LABWM) (Hevesi and Johnson, 2016) from INFIL3.0 (USGS, 2008a, 2008b) to INFIL4.0. The LABWM provides gridded monthly infiltration, evaporation, recharge, and runoff estimates for the Los Angeles region using the water balance recharge model, INFIL. INFIL is a grid-based, distributed-parameter, deterministic model that uses a daily time step to simulate the temporal and spatial distribution of the root-zone water balance, including net infiltration and potential recharge across the lower boundary of the root zone. INFIL3.0 was originally released and documented in 2008 (USGS, 2008a) and has been used and documented in several studies as the water-balance model used to develop spatially and temporally distributed estimates of recharge and runoff (Rewis and others, 2006; Hevesi and Christensen, 2015; Flint and Martin, 2012; Nishikawa and others, 2005; Hevesi and others, 2003; Paulinski, 2021a) including the LABWM (Hevesi and Johnson, 2016). The LABWM used the INFIL3.0 code with estimates of urban (landscape) irrigation to simulate the near-surface water balance from water years 1905 to 2014 for the Los Angeles Basin Watershed (Hevesi and Johnson, 2016) and to develop components of the recharge boundary condition for the Los Angeles Coastal Plain Groundwater Model (Reichard and others, 2003; Paulinski, 2021). Recently, there has been increased interest from stakeholders to update the Los Angeles Coastal Plain Groundwater Model (LACPGM) and thus there is a need to update the associated LABWM to include water years 2015 to 2020. To provide the updated water balance and recharge estimates, the INFIL3.0 code used in Hevesi and Johnson (2016) needed a modification to allow simulations to run past water year 2014. The modification made to update INFIL3.0 that result in the creation of INFIL4.0 involved increasing the array dimensions used for daily input variables, including precipitation, maximum and minimum air temperature, and surface water inflow, to allow for the increase in the total number of days in the extended simulation period (water years 1905 through 2020). The model archive included with this data release of the updated LABWM using INFIL4.0 includes the INFIL4.0 Fortran source code, the compiled INFIL4.0 executable file and related batch file, all input files needed to run the model from water year 1905 to 2020 for the 12 subdomains used in the LABWM, all simulation outputs for all subdomains, and a post-processing script (Monthmap). In addition to calculating the total potential recharge from contributing recharge areas outside the LACPGM boundary and recharge from interior LACPGM cells, the Monthmap script performs unit conversions (from millimeters per month to feet per day) and clips the output grid to match the areal extent of the LACPGM grid (Paulinski and others, 2021b).

This data release documents the datasets and procedures used to update the Los Angeles Basin Watershed Model (LABWM) (Hevesi and Johnson, 2016) from INFIL3.0 (USGS, 2008a, 2008b) to INFIL4.0. The LABWM provides gridded monthly infiltration, evaporation, recharge, and runoff estimates for the Los Angeles region using the water balance recharge model, INFIL. INFIL is a grid-based, distributed-parameter, deterministic model that uses a daily time step to simulate the temporal and spatial distribution of the root-zone water balance, including net infiltration and potential recharge across the lower boundary of the root zone. INFIL3.0 was originally released and documented in 2008 (USGS, 2008a) and has been used and documented in several studies as the water-balance model used to develop spatially and temporally distributed estimates of recharge and runoff (Rewis and others, 2006; Hevesi and Christensen, 2015; Flint and Martin, 2012; Nishikawa and others, 2005; Hevesi and others, 2003; Paulinski, 2021a) including the LABWM (Hevesi and Johnson, 2016). The LABWM used the INFIL3.0 code with estimates of urban (landscape) irrigation to simulate the near-surface water balance from water years 1905 to 2014 for the Los Angeles Basin Watershed (Hevesi and Johnson, 2016) and to develop components of the recharge boundary condition for the Los Angeles Coastal Plain Groundwater Model (Reichard and others, 2003; Paulinski, 2021). Recently, there has been increased interest from stakeholders to update the Los Angeles Coastal Plain Groundwater Model (LACPGM) and thus there is a need to update the associated LABWM to include water years 2015 to 2020. To provide the updated water balance and recharge estimates, the INFIL3.0 code used in Hevesi and Johnson (2016) needed a modification to allow simulations to run past water year 2014. The modification made to update INFIL3.0 that result in the creation of INFIL4.0 involved increasing the array dimensions used for daily input variables, including precipitation, maximum and minimum air temperature, and surface water inflow, to allow for the increase in the total number of days in the extended simulation period (water years 1905 through 2020). The model archive included with this data release of the updated LABWM using INFIL4.0 includes the INFIL4.0 Fortran source code, the compiled INFIL4.0 executable file and related batch file, all input files needed to run the model from water year 1905 to 2020 for the 12 subdomains used in the LABWM, all simulation outputs for all subdomains, and a post-processing script (Monthmap). In addition to calculating the total potential recharge from contributing recharge areas outside the LACPGM boundary and recharge from interior LACPGM cells, the Monthmap script performs unit conversions (from millimeters per month to feet per day) and clips the output grid to match the areal extent of the LACPGM grid (Paulinski and others, 2021b).