William H Farmer
Science and Products
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...
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...
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)%2
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 K
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. (CONUS) from October 1, 1980 through Se
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),...
Saxe, Samuel; Farmer, William; Driscoll, Jessica M.; Hogue, Terri S. 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...
Levin, Sara B.; Farmer, William H.
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...
Farmer, William H.; Kiang, Julie E.; Feaster, Toby D.; Eng, Ken 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...
Worland, Scott C.; Steinschneider, Scott; Farmer, William; Asquith, William H.; White, Rodney
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...
LaFontaine, Jacob H.; Hart, Rheannon M.; Hay, Lauren E.; Farmer, William H.; Bock, Andy R.; Viger, Roland J.; Markstrom, Steven L.; Regan, R. Steven; Driscoll, Jessica M. 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...
Velpuri, Naga Manohar; Senay, Gabriel; Driscoll, Jessica M.; Saxe, Samuel; Hay, Lauren E.; Farmer, William H.; Kiang, Julie E. 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...
Bock, Andrew R.; Farmer, William H.; Hay, Lauren E. 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 ...
Farmer, William H.; Over, Thomas M.; Kiang, Julie E.
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...
Evenson, Eric J.; Jones, Sonya A.; Barber, Nancy L.; Barlow, Paul M.; Blodgett, David L.; Bruce, Breton W.; Douglas-Mankin, Kyle R.; Farmer, William H.; Fischer, Jeffrey M.; Hughes, William B.; Kennen, Jonathan; Kiang, Julie E.; Maupin, Molly A.; Reeves, Howard W.; Senay, Gabriel B.; Stanton, Jennifer S.; Wagner, Chad R.; Wilson, Jennifer T.
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...
Over, Thomas M.; Farmer, William H.; Russell, Amy M. 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...
Fulton, John W.; Henneberg, Mark F.; Mills, Taylor J.; Kohn, Michael S.; Epstein, Brian; Hittle, Elizabeth ; Damschen, William C.; Laveau, Christopher D.; Lambrecht, Jason M.; Farmer, William H. Improving predictions of hydrological low-flow indices in ungaged basins using machine learning
We compare the ability of eight machine-learning models (elastic net, gradient boosting, kernel-k-nearest neighbors, two variants of support vector machines, M5-cubist, random forest, and a meta-learning ensemble M5-cubist model) and four baseline models (ordinary kriging, a unit area discharge model, and two variants of censored regression)...
Worland, Scott C.; Farmer, William H.; Kiang, Julie E.