Will Farmer is the Acting Director for the Northeast Climate Adaptation Science Center.
Science and Products
2022-24: Future of Aquatic Flows
The 2022-2024 Climate Adaptation Postdoctoral (CAP) Fellows cohort will explore how climate change is altering aquatic flows in streams and rivers across the country and how climate can be integrated into aquatic ecosystem management.
Visualizing the Invisible: Causes, Consequences, Changes, and Management of Streamflow Depletion Across the U.S.
Streamflow is declining in many parts of the United States (US) due to factors including groundwater pumping, land use change, and climate change. Streamflow depletion, a reduction in groundwater discharge to a stream due to human activities such as pumping and/or land use change, tends to evolve slowly and can be entirely invisible for many years to decades. This is because streamflow depletion c
Trend Reproduction
As part of the National Water Budget Project, our objective is to quantify how well observed trends are simulated.
Water availability for ungauged rivers: an integrative, multi-model approach to estimate water availability at ungauged rivers across the United States
There has been increasing attention placed on the need for water availability information at ungauged locations, particularly related to balancing human and ecological needs for water. Critical to assessing water availability is the necessity for daily streamflow time series; however, most of the rivers in the United States are ungauged. This proposal leverages over $1M currently allocated to the
Basin Characteristics and Streamflow Statistics for Selected Gages, Alaska, USA (ver. 2.0, September, 2022)
This data release documents the data used for the associated publication "Evaluating hydrologic region assignment techniques for ungaged watersheds in Alaska, USA" (Barnhart and others, 2022) The data sets within this release are stored in 14 files: (1) Streamflow observations and sites used. (2) Statistically estimated streamflow values computed for each site. (3) Streamflow statistics computed f
Statistical daily streamflow estimates at GAGES-II non-reference streamgages in the conterminous United States, Water Years 1981-2017
This data release contains daily time series estimates of natural streamflow at 5,439 GAGES-II non-reference streamgages in 19 study regions across the conterminous United States from October 1, 1980 through September 30, 2017, using five statistical techniques: nearest-neighbor drainage area ratio (NNDAR), map-correlation drainage area ratio (MCDAR), nearest-neighbor nonlinear spatial interpolati
Cross-validation results for five statistical methods of daily streamflow estimation at 1,385 reference streamgages in the conterminous United States, Water Years 1981-2017
This data release contains daily time series estimates of natural streamflow for 1,385 streamgages in 19 study regions in the conterminous U.S. from October 1, 1980, through September 30, 2017. These estimates are provided for gages from mostly undisturbed watersheds as defined by Falcone (2011), using five statistical techniques: nearest-neighbor drainage area ratio (NNDAR), map-correlation drain
Statistical daily streamflow estimates at HUC12 outlets in the conterminous United States, Water Years 1981-2017
This data release contains daily time series estimates of natural streamflow at the outlets of more than 80,000 12-digit hydrologic units in 19 study regions across the conterminous U.S. from October 1, 1980 through September 30, 2017, using three statistical techniques: Nearest-Neighbor Drainage Area Ratio (NNDAR), Map-Correlation Drainage Area Ratio (MCDAR), and Ordinary Kriging of the logarithm
Model Input and Output for Hydrologic Simulations of the Southeastern United States for Historical and Future Conditions
This data release contains inputs for and outputs from hydrologic simulations of the southeastern U.S. using the Monthly Water Balance Model, the Precipitation Runoff Modeling System (PRMS), and statistically-based methods. These simulations were developed to provide estimates of water availability and statistics of streamflow for historical and potential future conditions for an area of approxima
Water-quality trends and trend component estimates for the Nation's rivers and streams using Weighted Regressions on Time, Discharge, and Season (WRTDS) models and generalized flow normalization, 1972-2012
Nonstationary streamflow due to environmental and human-induced causes can affect water quality over time, yet these effects are poorly accounted for in water-quality trend models. This data release provides instream water-quality trends and estimates of two components of change, for sites across the Nation previously presented in Oelsner et al. (2017). We used previously calibrated Weighted Regre
7Q10 Records and Basin Characteristics for 173 basins in Arkansas, Iowa, Kansas, Missouri, Nebraska, and Oklahoma (2017)
This data release replicates the methods detailed in the 2017 publication titled "Improving predictions of hydrological low-flow indices in ungaged basins using machine learning" for a different data set. The original data set and the associated readme file for the model archive can be viewed here: https://doi.org/10.5066/F7CR5S4T. The original data set contained streamflow data for sites located
Streamflow, flow-duration curves, basin characteristics, and regression models of flow-duration curves for selected streamgages in the conterminous United States
This data release contains the input used and the output files interpreted in the publication 'Refinement of a Regression-Based Method for Prediction of Flow-Duration Curves of Daily Streamflow in the Conterminous United States'. This data release contains daily streamflow data for 1,378 streamgages in 19 study regions in the conterminous U.S. from October 1, 1980 through September 30, 2013 from m
Bias correction of Simulated Historical Daily Streamflow at Ungauged Locations Using Independently Estimated Flow-Duration Curves: Data Release
This dataset contains the observed and simulated streamflow used to produce the results of the journal article entitled Bias correction of Retrospective Simulation of Daily Streamflow at Ungauged Locations Using Independently Estimated Flow-Duration Curves . Observed streamflow, retrieved from the U.S. Geological Surveys National Water Information System (https://waterdata.usgs.gov/nwis) in Spring
Characterizing Uncertainty in Daily Streamflow Estimates at Ungauged Locations in Support of the Massachusetts Sustainable Yield Estimator: Data Release
This data set archives all inputs, outputs and scripts needed to reproduce the findings of W.H. Farmer and S. Levin in the 2017 Journal of the American Water Resources Association article entitled Characterizing Uncertainty in Daily Streamflow Estimates at Ungauged Locations in Support of the Massachusetts Sustainable Yield Estimator. Input data includes observed streamflow values, in cubic feet
Geospatial Tools Effectively Estimate Nonexceedance Probabilities of Daily Streamflow at Ungaged and Intermittently Gaged Locations in Ohio: Data Release
This data set archives all inputs, outputs and scripts needed to reproduce the findings of W.H. Farmer and G.F. Koltun in the 2017 Journal of Hydrology Regional Studies article entitled Geospatial Tools Effectively Estimated Nonexceedance Probabilities of Daily Streamflow at Ungauged and Intermittently Gauged Locations in Ohio. Input data includes observed streamflow values, in cubic feet per seco
7Q10 records and basin characteristics for 224 basins in South Carolina, Georgia, and Alabama (2015)
This data release provides the data and R scripts used for the 2017 submitted publication titled "Improving predictions of hydrological low-flow indices in ungaged basins using machine learning". There are two .csv files and 14 R-scripts included below. The lowflow_sc_ga_al_gagesII_2015.csv datafile contains the annual minimum seven-day mean streamflow with an annual exceedance probability of 90%
Filter Total Items: 23
Evaluating hydrologic region assignment techniques for ungaged basins in Alaska, USA
Building continental-scale hydrologic models in data-sparse regions requires an understanding of spatial variation in hydrologic processes. Extending these models to ungaged locations requires techniques to group ungaged locations with gaged ones to make process importance and model parameter transfer decisions to ungaged locations. This analysis (1) tested the utility of fundamental streamflow st
Implications of model selection: A comparison of publicly available, conterminous US-extent hydrologic component estimates
Spatiotemporally continuous estimates of the hydrologic cycle are often generated through hydrologic modeling, reanalysis, or remote sensing (RS) methods and are commonly applied as a supplement to, or a substitute for, in situ measurements when observational data are sparse or unavailable. This study compares estimates of precipitation (P), actual evapotranspiration (ET), runoff (R), snow water e
Regionalization of surface-water statistics using multiple linear regression
This report serves as a reference document in support of the regionalization of surface-water statistics using multiple linear regression. Streamflow statistics are quantitative characterizations of hydrology and are often derived from observed streamflow records. In the absence of observed streamflow records, as at unmonitored or ungaged locations, other techniques are required. Multiple linear r
Evaluation of uncertainty intervals for daily, statistically derived streamflow estimates at ungaged basins across the continental U.S.
Streamflow estimation methods that transfer information from an index gage to an ungaged site are commonly used; however, uncertainty in daily streamflow estimates are often not adequately quantified. In this study, daily streamflow was simulated at 1,331 validation streamgages across the continental United States using four transfer-based streamflow estimation methods. Empirical 95 percent unce
Copula theory as a generalized framework for flow-duration curve-based streamflow estimates in ungaged and partially gaged catchments
Flow‐duration curve (FDC) based streamflow estimation methods involve estimating an FDC at an ungaged or partially gaged location and using the time series of nonexceedance probabilities estimated from donor streamgage sites to generate estimates of streamflow. We develop a mathematical framework to illustrate the connection between copulas and prior FDC‐based approaches. The performance of copula
Simulation of water availability in the Southeastern United States for historical and potential future climate and land-cover conditions
A study was conducted by the U.S. Geological Survey (USGS), in cooperation with the Gulf Coastal Plains and Ozarks Landscape Conservation Cooperative (GCPO LCC) and the Department of the Interior Southeast Climate Adaptation Science Center, to evaluate the hydrologic response of a daily time step hydrologic model to historical observations and projections of potential climate and land-cover change
GRACE storage change characteristics (2003–2016) over major surface basins and principal aquifers in the Conterminous United States
In this research, we characterized the changes in Gravity Recovery and Climate Experiment’s (GRACE) monthly total water storage anomaly (TWSA) in 18 surface basins and 12 principal aquifers in the Conterminous United States (CONUS) over 2003–2016. Regions with high variability in storage were identified. Ten basins and 4 aquifers showed significant change in storage. Eight surface basins and 8 aqu
Quantifying uncertainty in simulated streamflow and runoff from a continental-scale monthly water balance model
One important component of continental-scale hydrologic modeling is quantifying the level of uncertainty in long-term hydrologic simulations and providing a range of possible simulated streamflow and/or runoff values for gaged and ungaged locations. In this paper, uncertainty was quantified for simulated streamflow and runoff generated from a monthly water balance model (MWBM) at 1575 streamgages
Bias correction of simulated historical daily streamflow at ungauged locations by using independently estimated flow duration curves
In many simulations of historical daily streamflow distributional bias arising from the distributional properties of residuals has been noted. This bias often presents itself as an underestimation of high streamflow and an overestimation of low streamflow. Here, 1168 streamgages across the conterminous USA, having at least 14 complete water years of daily data between 1 October 1980 and 30 Septemb
Continuing progress toward a national assessment of water availability and use
Executive SummaryThe Omnibus Public Land Management Act of 2009 (Public Law 111—11) was passed into law on March 30, 2009. Subtitle F, also known as the SECURE Water Act, calls for the establishment of a “national water availability and use assessment program” within the U.S. Geological Survey (USGS). The USGS issued the first report on the program in 2013. Program progress over the period 2013–17
Refinement of a regression-based method for prediction of flow-duration curves of daily streamflow in the conterminous United States
Regional regression is a common tool used to estimate daily flow-duration curves (FDCs) at ungaged locations. In this report, several refinements to a particular implementation of the regional regression method for estimating FDCs are evaluated by consideration of different methodological options through a leave-one-out cross-validation procedure in the 19 major river basins of the conterminous Un
Computing under-ice discharge: A proof-of-concept using hydroacoustics and the Probability Concept
Under-ice discharge is estimated using open-water reference hydrographs; however, the ratings for ice-affected sites are generally qualified as poor. The U.S. Geological Survey (USGS), in collaboration with the Colorado Water Conservation Board, conducted a proof-of-concept to develop an alternative method for computing under-ice discharge using hydroacoustics and the Probability Concept.The study
Science and Products
- Science
2022-24: Future of Aquatic Flows
The 2022-2024 Climate Adaptation Postdoctoral (CAP) Fellows cohort will explore how climate change is altering aquatic flows in streams and rivers across the country and how climate can be integrated into aquatic ecosystem management.Visualizing the Invisible: Causes, Consequences, Changes, and Management of Streamflow Depletion Across the U.S.
Streamflow is declining in many parts of the United States (US) due to factors including groundwater pumping, land use change, and climate change. Streamflow depletion, a reduction in groundwater discharge to a stream due to human activities such as pumping and/or land use change, tends to evolve slowly and can be entirely invisible for many years to decades. This is because streamflow depletion cTrend Reproduction
As part of the National Water Budget Project, our objective is to quantify how well observed trends are simulated.Water availability for ungauged rivers: an integrative, multi-model approach to estimate water availability at ungauged rivers across the United States
There has been increasing attention placed on the need for water availability information at ungauged locations, particularly related to balancing human and ecological needs for water. Critical to assessing water availability is the necessity for daily streamflow time series; however, most of the rivers in the United States are ungauged. This proposal leverages over $1M currently allocated to the - Data
Basin Characteristics and Streamflow Statistics for Selected Gages, Alaska, USA (ver. 2.0, September, 2022)
This data release documents the data used for the associated publication "Evaluating hydrologic region assignment techniques for ungaged watersheds in Alaska, USA" (Barnhart and others, 2022) The data sets within this release are stored in 14 files: (1) Streamflow observations and sites used. (2) Statistically estimated streamflow values computed for each site. (3) Streamflow statistics computed fStatistical daily streamflow estimates at GAGES-II non-reference streamgages in the conterminous United States, Water Years 1981-2017
This data release contains daily time series estimates of natural streamflow at 5,439 GAGES-II non-reference streamgages in 19 study regions across the conterminous United States from October 1, 1980 through September 30, 2017, using five statistical techniques: nearest-neighbor drainage area ratio (NNDAR), map-correlation drainage area ratio (MCDAR), nearest-neighbor nonlinear spatial interpolatiCross-validation results for five statistical methods of daily streamflow estimation at 1,385 reference streamgages in the conterminous United States, Water Years 1981-2017
This data release contains daily time series estimates of natural streamflow for 1,385 streamgages in 19 study regions in the conterminous U.S. from October 1, 1980, through September 30, 2017. These estimates are provided for gages from mostly undisturbed watersheds as defined by Falcone (2011), using five statistical techniques: nearest-neighbor drainage area ratio (NNDAR), map-correlation drainStatistical daily streamflow estimates at HUC12 outlets in the conterminous United States, Water Years 1981-2017
This data release contains daily time series estimates of natural streamflow at the outlets of more than 80,000 12-digit hydrologic units in 19 study regions across the conterminous U.S. from October 1, 1980 through September 30, 2017, using three statistical techniques: Nearest-Neighbor Drainage Area Ratio (NNDAR), Map-Correlation Drainage Area Ratio (MCDAR), and Ordinary Kriging of the logarithmModel Input and Output for Hydrologic Simulations of the Southeastern United States for Historical and Future Conditions
This data release contains inputs for and outputs from hydrologic simulations of the southeastern U.S. using the Monthly Water Balance Model, the Precipitation Runoff Modeling System (PRMS), and statistically-based methods. These simulations were developed to provide estimates of water availability and statistics of streamflow for historical and potential future conditions for an area of approximaWater-quality trends and trend component estimates for the Nation's rivers and streams using Weighted Regressions on Time, Discharge, and Season (WRTDS) models and generalized flow normalization, 1972-2012
Nonstationary streamflow due to environmental and human-induced causes can affect water quality over time, yet these effects are poorly accounted for in water-quality trend models. This data release provides instream water-quality trends and estimates of two components of change, for sites across the Nation previously presented in Oelsner et al. (2017). We used previously calibrated Weighted Regre7Q10 Records and Basin Characteristics for 173 basins in Arkansas, Iowa, Kansas, Missouri, Nebraska, and Oklahoma (2017)
This data release replicates the methods detailed in the 2017 publication titled "Improving predictions of hydrological low-flow indices in ungaged basins using machine learning" for a different data set. The original data set and the associated readme file for the model archive can be viewed here: https://doi.org/10.5066/F7CR5S4T. The original data set contained streamflow data for sites locatedStreamflow, flow-duration curves, basin characteristics, and regression models of flow-duration curves for selected streamgages in the conterminous United States
This data release contains the input used and the output files interpreted in the publication 'Refinement of a Regression-Based Method for Prediction of Flow-Duration Curves of Daily Streamflow in the Conterminous United States'. This data release contains daily streamflow data for 1,378 streamgages in 19 study regions in the conterminous U.S. from October 1, 1980 through September 30, 2013 from mBias correction of Simulated Historical Daily Streamflow at Ungauged Locations Using Independently Estimated Flow-Duration Curves: Data Release
This dataset contains the observed and simulated streamflow used to produce the results of the journal article entitled Bias correction of Retrospective Simulation of Daily Streamflow at Ungauged Locations Using Independently Estimated Flow-Duration Curves . Observed streamflow, retrieved from the U.S. Geological Surveys National Water Information System (https://waterdata.usgs.gov/nwis) in SpringCharacterizing Uncertainty in Daily Streamflow Estimates at Ungauged Locations in Support of the Massachusetts Sustainable Yield Estimator: Data Release
This data set archives all inputs, outputs and scripts needed to reproduce the findings of W.H. Farmer and S. Levin in the 2017 Journal of the American Water Resources Association article entitled Characterizing Uncertainty in Daily Streamflow Estimates at Ungauged Locations in Support of the Massachusetts Sustainable Yield Estimator. Input data includes observed streamflow values, in cubic feetGeospatial Tools Effectively Estimate Nonexceedance Probabilities of Daily Streamflow at Ungaged and Intermittently Gaged Locations in Ohio: Data Release
This data set archives all inputs, outputs and scripts needed to reproduce the findings of W.H. Farmer and G.F. Koltun in the 2017 Journal of Hydrology Regional Studies article entitled Geospatial Tools Effectively Estimated Nonexceedance Probabilities of Daily Streamflow at Ungauged and Intermittently Gauged Locations in Ohio. Input data includes observed streamflow values, in cubic feet per seco7Q10 records and basin characteristics for 224 basins in South Carolina, Georgia, and Alabama (2015)
This data release provides the data and R scripts used for the 2017 submitted publication titled "Improving predictions of hydrological low-flow indices in ungaged basins using machine learning". There are two .csv files and 14 R-scripts included below. The lowflow_sc_ga_al_gagesII_2015.csv datafile contains the annual minimum seven-day mean streamflow with an annual exceedance probability of 90% - Publications
Filter Total Items: 23
Evaluating hydrologic region assignment techniques for ungaged basins in Alaska, USA
Building continental-scale hydrologic models in data-sparse regions requires an understanding of spatial variation in hydrologic processes. Extending these models to ungaged locations requires techniques to group ungaged locations with gaged ones to make process importance and model parameter transfer decisions to ungaged locations. This analysis (1) tested the utility of fundamental streamflow stImplications of model selection: A comparison of publicly available, conterminous US-extent hydrologic component estimates
Spatiotemporally continuous estimates of the hydrologic cycle are often generated through hydrologic modeling, reanalysis, or remote sensing (RS) methods and are commonly applied as a supplement to, or a substitute for, in situ measurements when observational data are sparse or unavailable. This study compares estimates of precipitation (P), actual evapotranspiration (ET), runoff (R), snow water eRegionalization of surface-water statistics using multiple linear regression
This report serves as a reference document in support of the regionalization of surface-water statistics using multiple linear regression. Streamflow statistics are quantitative characterizations of hydrology and are often derived from observed streamflow records. In the absence of observed streamflow records, as at unmonitored or ungaged locations, other techniques are required. Multiple linear rEvaluation of uncertainty intervals for daily, statistically derived streamflow estimates at ungaged basins across the continental U.S.
Streamflow estimation methods that transfer information from an index gage to an ungaged site are commonly used; however, uncertainty in daily streamflow estimates are often not adequately quantified. In this study, daily streamflow was simulated at 1,331 validation streamgages across the continental United States using four transfer-based streamflow estimation methods. Empirical 95 percent unceCopula theory as a generalized framework for flow-duration curve-based streamflow estimates in ungaged and partially gaged catchments
Flow‐duration curve (FDC) based streamflow estimation methods involve estimating an FDC at an ungaged or partially gaged location and using the time series of nonexceedance probabilities estimated from donor streamgage sites to generate estimates of streamflow. We develop a mathematical framework to illustrate the connection between copulas and prior FDC‐based approaches. The performance of copulaSimulation of water availability in the Southeastern United States for historical and potential future climate and land-cover conditions
A study was conducted by the U.S. Geological Survey (USGS), in cooperation with the Gulf Coastal Plains and Ozarks Landscape Conservation Cooperative (GCPO LCC) and the Department of the Interior Southeast Climate Adaptation Science Center, to evaluate the hydrologic response of a daily time step hydrologic model to historical observations and projections of potential climate and land-cover changeGRACE storage change characteristics (2003–2016) over major surface basins and principal aquifers in the Conterminous United States
In this research, we characterized the changes in Gravity Recovery and Climate Experiment’s (GRACE) monthly total water storage anomaly (TWSA) in 18 surface basins and 12 principal aquifers in the Conterminous United States (CONUS) over 2003–2016. Regions with high variability in storage were identified. Ten basins and 4 aquifers showed significant change in storage. Eight surface basins and 8 aquQuantifying uncertainty in simulated streamflow and runoff from a continental-scale monthly water balance model
One important component of continental-scale hydrologic modeling is quantifying the level of uncertainty in long-term hydrologic simulations and providing a range of possible simulated streamflow and/or runoff values for gaged and ungaged locations. In this paper, uncertainty was quantified for simulated streamflow and runoff generated from a monthly water balance model (MWBM) at 1575 streamgagesBias correction of simulated historical daily streamflow at ungauged locations by using independently estimated flow duration curves
In many simulations of historical daily streamflow distributional bias arising from the distributional properties of residuals has been noted. This bias often presents itself as an underestimation of high streamflow and an overestimation of low streamflow. Here, 1168 streamgages across the conterminous USA, having at least 14 complete water years of daily data between 1 October 1980 and 30 SeptembContinuing progress toward a national assessment of water availability and use
Executive SummaryThe Omnibus Public Land Management Act of 2009 (Public Law 111—11) was passed into law on March 30, 2009. Subtitle F, also known as the SECURE Water Act, calls for the establishment of a “national water availability and use assessment program” within the U.S. Geological Survey (USGS). The USGS issued the first report on the program in 2013. Program progress over the period 2013–17Refinement of a regression-based method for prediction of flow-duration curves of daily streamflow in the conterminous United States
Regional regression is a common tool used to estimate daily flow-duration curves (FDCs) at ungaged locations. In this report, several refinements to a particular implementation of the regional regression method for estimating FDCs are evaluated by consideration of different methodological options through a leave-one-out cross-validation procedure in the 19 major river basins of the conterminous UnComputing under-ice discharge: A proof-of-concept using hydroacoustics and the Probability Concept
Under-ice discharge is estimated using open-water reference hydrographs; however, the ratings for ice-affected sites are generally qualified as poor. The U.S. Geological Survey (USGS), in collaboration with the Colorado Water Conservation Board, conducted a proof-of-concept to develop an alternative method for computing under-ice discharge using hydroacoustics and the Probability Concept.The study