David M Wolock, Ph.D.
Science and Products
A digital crust to advance continental‐scale modeling of subsurface fluid flow in climate, crustal process, and Earth system models
Fluid circulation in the Earth’s crust plays an essential role in surface, near surface, and crustal dynamics. Near the surface, soil water and groundwater interact with each other and with rivers, lakes and wetlands, affecting weathering, soil formation, ecosystem evolution and biogeochemical cycles. Further down (1km), fluid flow affects diagenesis, hydrocarbon maturation and migration, ore...
Severity and extent of alterations to natural streamflow regimes based on hydrologic metrics in the conterminous United States, 1980–2014
Alteration of the natural streamflow regime by land and water management, such as land-cover change and dams, is associated with aquatic ecosystem degradation. The severity and geographic extent of streamflow alteration at regional and national scales, however, remain largely unquantified. The primary goal of this study is to characterize the...
Eng, Ken; Carlisle, Daren M.; Grantham, Theodore E.; Wolock, David M.; Eng, Rosaly L.
Flow modification in the Nation’s streams and rivers
This report summarizes a national assessment of flowing waters conducted by the U.S. Geological Survey’s (USGS) National Water-Quality Assessment (NAWQA) Project and addresses several pressing questions about the modification of natural flows in streams and rivers. The assessment is based on the integration, modeling, and synthesis of...
Carlisle, Daren M.; Wolock, David M.; Konrad, Christopher P.; McCabe, Gregory J.; Eng, Ken; Theodore E. Grantham; Mahler, Barbara
Streamflow—Water year 2018
The maps and graphs in this summary describe national streamflow conditions for water year 2018 (October 1, 2017, to September 30, 2018) in the context of streamflow ranks relative to the 89-year period of water years 1930–2018. The illustrations are based on observed data from the U.S. Geological Survey National Streamflow Network. Annual runoff...
Jian, Xiaodong; Wolock, David M.; Brady, Steven J.; Lins, Harry F.
Regional-scale associations between indicators of biological integrity and indicators of streamflow modification
Although streamflow is widely recognized as a controlling factor in stream health, empirical relations between indicators of anthropogenic modification of streamflow and ecological indicators have been elusive. The objective of this report is to build upon specific findings reported in recent publications by providing a library of empirical models...
Carlisle, Daren M.; Grantham, Theodore E.; Eng, Ken; Wolock, David M.
A new indicator framework for quantifying the intensity of the terrestrialwater cycle
A quantitative framework for characterizing the intensity of the water cycle over land is presented, and illustrated using a spatially distributed water-balance model of the conterminous United States (CONUS). We approach water cycle intensity (WCI) from a landscape perspective; WCI is defined as the sum of precipitation (P) and actual...
Huntington, Thomas G.; Weiskel, Peter; Wolock, David M.; McCabe, Gregory J. A database of natural monthly streamflow estimates from 1950 to 2015 for the conterminous United States
Quantifying and understanding the natural streamflow regime, defined as expected streamflow that would occur in the absence of anthropogenic modification to the hydrologic system, is critically important for the development of management strategies aimed at protecting aquatic ecosystems. Water balance models have been applied frequently to...
Miller, Matthew P.; Carlisle, Daren M.; Wolock, David M.; Wieczorek, Michael
Streamflow - Water Year 2017
The maps and graphs in this summary describe national streamflow conditions for water year 2017 (October 1, 2016, to September 30, 2017) in the context of streamflow ranks relative to the 88-year period of 1930–2017, unless otherwise noted. The illustrations are based on observed data from the U.S. Geological Survey (USGS) National Streamflow...
Jian, Xiaodong; Wolock, David M.; Brady, Steven J.; Lins, Harry F.
Variability of hydrological droughts in the conterminous United States, 1951 through 2014
Spatial and temporal variability in the frequency, duration, and severity of hydrological droughts across the conterminous United States (CONUS) was examined using monthly mean streamflow measured at 872 sites from 1951 through 2014. Hydrological drought is identified as starting when streamflow falls below the 20th percentile streamflow value for...
Austin, Samuel H.; Wolock, David M.; Nelms, David L.
A conceptual framework for effectively anticipating water-quality changes resulting from changes in agricultural activities
Agricultural activities can affect water quality and the health of aquatic ecosystems; many water-quality issues originate with the movement of water, agricultural chemicals, and eroded soil from agricultural areas to streams and groundwater. Most agricultural activities are designed to sustain or increase crop production, while some are designed...
Capel, Paul D.; Wolock, David M.; Coupe, Richard H.; Roth, Jason L. Predictability and selection of hydrologic metrics in riverine ecohydrology
The natural flow regime is critical to the health of riverine ecosystems. Many hydrologic metrics (HMs) have been developed to describe natural flow regimes, quantify flow alteration, and provide the hydrologic foundation for the development of environmental flow standards. Many applications require the use of models to predict expected natural...
Eng, Ken; Grantham, Theodore E.; Carlisle, Daren M.; Wolock, David M. Estimating discharge and nonpoint source nitrate loading to streams from three end‐member pathways using high‐frequency water quality data
The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high‐frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify...
Miller, Matthew P.; Tesoriero, Anthony J.; Hood, Krista; Terziotti, Silvia; Wolock, David M. Biological relevance of streamflow metrics: Regional and national perspectives
Protecting the health of streams and rivers requires identifying ecologically significant attributes of the natural flow regime. Streamflow regimes are routinely quantified using a plethora of hydrologic metrics (HMs), most of which have unknown relevance to biological communities. At regional and national scales, we evaluated which of 509...
Carlisle, Daren M.; Grantham, Theodore E.; Eng, Ken; Wolock, David M.
Software Release - RSPARROW: An R system for SPARROW modeling
RSPARROW, now available on the USGS GitLab repository, provides the first open-source version of the USGS SPARROW water-quality model, with new features that improve the utility of the model for conducting studies of contaminants in surface waters and informing water resource management decisions.