Judson W. Harvey

United States Geological Survey | USGS · Earth System Processes Division

Streams that only flow occasionally are major contributors to river flow

The concentration of chlorophyll a in phytoplankton and periphyton represents the amount of algal biomass. We compiled an 18-year record (2005–2022) of pigment data from water bodies across the United States (US) to support efforts to develop process-based, machine learning, and remote sensing models for prediction of harmful algal blooms (HABs). T...

Measurement of planktonic chlorophyll‐a—a proxy for algal biomass—in rivers may represent local production or algae transported from upstream, confounding understanding of algal bloom development in flowing waters. We modeled 3 years of chlorophyll‐a transport through a 394‐km portion of the Illinois River and found that although algal biomass is l...

Metabolism estimates organic carbon accumulation by primary productivity and removal by respiration. In rivers it is relevant to assessing trophic status and threats to river health such as hypoxia as well as greenhouse gas fluxes. We estimated metabolism in 17 rivers of the Illinois River basin (IRB) for a total of 15,176 days, or an average of 2....

Increases in fluxes of nitrogen (N) and phosphorus (P) in the environment have led to negative impacts affecting drinking water, eutrophication, harmful algal blooms, climate change, and biodiversity loss. Because of the importance, scale, and complexity of these issues, it may be useful to consider methods for prioritizing nutrient research in rep...

River ecosystem function depends on flow regimes that are increasingly modified by changes in climate, land use, water extraction, and flow regulation. Given the wide range of variation in flow regime modifications and autotrophic communities in rivers, it has been challenging to predict which rivers will be more resilient to flow disturbances. To...

Eutrophication is one of the largest threats to aquatic ecosystems and chlorophyll a measurements are relevant indicators of trophic state and algal abundance. Many studies have modeled chlorophyll a in rivers but model development and testing has largely occurred at individual sites which hampers creating generalized models capable of making broad...

River corridors integrate the active channels, geomorphic floodplain and riparian areas, and hyporheic zone while receiving inputs from the uplands and groundwater and exchanging mass and energy with the atmosphere. Here, we trace the development of the contemporary understanding of river corridors from the perspectives of geomorphology, hydrology,...

Hypoxia in coastal waters and lakes is widely recognized as a detrimental environmental issue, yet we lack a comparable understanding of hypoxia in rivers. We investigated controls on hypoxia using 118 million paired observations of dissolved oxygen (DO) concentration and water temperature in over 125,000 locations in rivers from 93 countries. We f...

Groundwater/surface‐water (GW/SW) exchange and hyporheic processes are topics receiving increasing attention from the hydrologic community. Hydraulic, chemical, temperature, geophysical, and remote sensing methods are used to achieve various goals (e.g., inference of GW/SW exchange, mapping of bed materials, etc.), but the application of these meth...

Significance This paper provides a comprehensive analysis of the annual patterns of ecosystem productivity and respiration for more than 200 rivers, comparing the magnitude and phenology of river metabolic regimes with annual estimates from more than 150 terrestrial ecosystems. Although mean annual temperature and mean annual precipitation explain...

Nutrients that have gradually accumulated in soils, groundwaters, and river sediments in the United States over the past century can remobilize and increase current downstream loading, obscuring effects of conservation practices aimed at protecting water resources. Drivers of storage accumulation and release of nutrients are poorly understood at th...

Plain Language Summary The conversion of solar energy to organic matter through photosynthesis is an important component of global carbon cycling. While there are global estimates of solar radiation at the Earth's surface, primary producers in rivers often only receive a small percentage of incoming light due to reductions from riparian shading, wa...

River corridors supply a substantial proportion of the fresh water for societal and ecological needs. Individual functions of flowing (lotic) streams and rivers and ponded (lentic) waterbodies such as lakes and reservoirs are well-studied, but their collective functions are not as well understood. Here we bring together nationally consistent river...

In this paper, we develop and validate a rigorous modeling framework, based on Duhamel's Theorem, for the unsteady one‐dimensional vertical transport of a solute across a flat sediment‐water interface (SWI) and through the benthic biolayer of a turbulent stream. The modeling framework is novel in capturing the two‐way coupling between evolving solu...

Many water quality and ecosystem functions performed by streams occur in the benthic biolayer, the biologically active upper (~5 cm) layer of the streambed. Solute transport through the benthic biolayer is facilitated by bedform pumping, a physical process in which dynamic and static pressure variations over the surface of stationary bedforms (e.g....

Retention, processing, and transport of solutes and particulates in stream corridors are influenced by the travel time of streamflow through stream channels, which varies dynamically with discharge. The effects of streamflow variability across sites and over time cannot be addressed by time-averaged models if parameters are based solely on the char...

The sediment–water interfaces (SWI) of streams serve as important biogeochemical hotspots in watersheds and contribute to whole-catchment reactive nitrogen budgets and water-quality conditions. Recently, the SWI has been identified as an important source of nitrous oxide (N2O) produced in streams, with SWI residence time among the principal control...

River corridors store, convey, and process nutrients from terrestrial and upstream sources, regulating delivery from headwaters to estuaries. A consequence of chronic excess nitrogen loading, as supported by theory and field studies in specific watersheds, is saturation of the biogeochemically-mediated nitrogen removal processes that weakens the ca...

This preprint is in review with Water Resources Research, but also posted on the Open Access forum ESSOar. You can access the full manuscript at the following URL: https://www.essoar.org/doi/10.1002/essoar.10501298.1 Below is the abstract, and plain language abstract, for the article: Turbulent Mixing in the Benthic Biolayer of Streams Stanley B....

Biogeochemical gradients in streambeds are steep and can vary over short distances often making adequate characterisation of sediment biogeochemical processes challenging. This paper provides an overview and comparison of streambed pore-water sampling methods, highlighting their capacity to address gaps in our understanding of streambed biogeochemi...

Floodplain inundation poses both risks and benefits to society. In this study, we characterize floodplain inundation across the United States using 5800 stream gages. We find that between 4% and 12.6% of a river’s annual flow moves through its floodplains. Flood duration and magnitude is greater in large rivers, whereas the frequency of events is g...

Small ponds—farm ponds, detention ponds, or impoundments below 0.01 km²—serve important human needs throughout most large river basins. Yet the role of small ponds in regional nutrient and sediment budgets is essentially unknown, currently making it impossible to evaluate their management potential to achieve water quality objectives. Here we used...

For many glacial lakes with highly permeable sediments, water exchange rates control hydrologic residence times within the sediment‐water interface (SWI) and the removal of reactive compounds such as nitrate, a common pollutant in lakes and groundwater. Here we conducted a series of focused tracer injection experiments in the upper 20 cm of the nat...

Although seasonal patterns of ecosystem productivity have been extensively described and analyzed with respect to their primary forcings in terrestrial and marine systems, comparatively little is known about these same processes in rivers. However, it is now possible to perform a large‐scale synthesis on the patterns and drivers of river productivi...

A national-scale quantification of metabolic energy flow in streams and rivers can improve understanding of the temporal dynamics of in-stream activity, links between energy cycling and ecosystem services, and the effects of human activities on aquatic metabolism. The two dominant terms in aquatic metabolism, gross primary production (GPP) and aero...

Brook trout (Salvelinus fontinalis) spawn in fall and overwintering egg development can benefit from stable, relatively warm temperatures in groundwater-seepage zones. However, eggs are also sensitive to dissolved oxygen concentration, which may be reduced in discharging groundwater (i.e., seepage). We investigated a 2 km reach of the coastal Quash...

Downstream flow in rivers is repeatedly delayed by hydrologic exchange with off‐channel storage zones where biogeochemical processing occurs. We present a dimensionless metric that quantifies river connectivity as the balance between downstream flow and the exchange of water with the bed, banks, and floodplains. The degree of connectivity directly...

Lakes, reservoirs, and other ponded waters are ubiquitous features of the aquatic landscape, yet their cumulative role in nitrogen removal in large river basins is often unclear. Here we use predictive modeling, together with comprehensive river water quality, land use, and hydrography datasets, to examine and explain the influences of more than 18...

Quantifying coupled mobile/less-mobile porosity dynamics is critical to the prediction of biogeochemical storage, release, and transformation processes in the zone where groundwater and surface water exchange. The recent development of fine-scale geoelectrical monitoring paired with pore-water sampling in groundwater systems enables direct characte...

Stream restoration goals include reducing erosion and increasing hyporheic exchange to promote biogeochemical processing and improve water quality. Little is known, however, about fine particle dynamics in response to stream restoration. Fine particles (<100 μm) are exchanged with transient storage areas near and within streambeds and banks. Fine p...

Brook trout (Salvelinus fontinalis) spawn in fall, and overwintering egg development can benefit from stable, relatively warm temperatures in groundwater seepage zones. However, eggs also are sensitive to dissolved oxygen concentration, which may be reduced in discharging groundwater. We investigated a 2-km reach of the coastal Quashnet River, Cape...

Knowledge of gas exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases, and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify gas transfer velocities in wetlands, and many wind speed/gas exchange parameterizations used in oceanographi...

The processes and biomass that characterize any ecosystem are fundamentally constrained by the total amount of energy that is either fixed within or delivered across its boundaries. Ultimately, ecosystems may be understood and classified by their rates of total and net productivity and by the seasonal patterns of photosynthesis and respiration. Suc...

Hydrologic exchange fluxes (HEFs) vary significantly along river corridors due to spatio-temporal changes in discharge and geomorphology. This variability results in the emergence of biogeochemical hot-spots and hot-moments that ultimately control solute and energy transport and ecosystem services from the local to the watershed scales. In this wor...

The Everglades is a low-gradient floodplain predominantly on organic soil that undergoes seasonally pulsing sheetflow through a network of deepwater sloughs separated by slightly higher elevation ridges. The seasonally pulsing flow permitted the coexistence of ridge and slough vegetation, including the persistence of productive, well-connected slou...

Carbon fixation and respiration in flowing waterways play significant roles in global and regional carbon budgets, yet how land use and watershed management interact with temporal disturbances (storms) to influence metabolism remains poorly understood. Here, we combine long-term with synoptic sampling of metabolism and its variable controls in neig...

Fine particles (1-100 µm), including particulate organic carbon (POC) and fine sediment, influence stream ecological functioning because they may contain or have a high affinity to sorb nitrogen and phosphorus. These particles are immobilized within stream storage areas, especially hyporheic sediments and benthic biofilms. However, fine particles a...

Disturbances such as fire or flood, in addition to changing the local magnitude of ecological, hydrological, or biogeochemical processes, can also change their functional connectivity—how those processes interact in space. Complex networks offer promise for quantifying functional connectivity in watersheds. The approach resolves connections between...

Shallow benthic biolayers at the top of the streambed are believed to be places of enhanced biogeochemical turnover within the hyporheic zone. They can be investigated by reactive stream tracer tests with tracer recordings in the streambed and in the stream channel. Common in-stream measurements of such reactive tracers cannot localize where the pr...

The actively flowing waters of streams and rivers remain in close contact with surrounding off-channel and subsurface environments. These hydrologic linkages between relatively fast flowing channel waters, with more slowly flowing waters off-channel and in the subsurface, are collectively referred to as hydrologic exchange flows (HEFs). HEFs includ...

Reactive tracer tests with the compound resazurin are often conducted in streams to determine hyporheic exchange parameters and investigate stream metabolism. Metabolic reactivity is closely linked to the hyporheic zone, and it was the aim of this study to assess the contributions of benthic biolayers, layers of increased reactivity at the top of i...

Restoration of higher flows through the Everglades is intended to reestablish sheetflow to rebuild a well-functioning ridge and slough landscape that supports a productive and diverse ecosystem. Our objective of the study was to use hydrologic simulations and biophysical analysis to predict restoration outcomes for five major subbasins of the Everg...

The pre-drainage Everglades was characterized by a continuum of clean, flowing freshwater from just south of present-day Orlando, down the Kissimmee River, through Lake Okeechobee, across the “River of Grass”, and ultimately into Florida Bay and the Gulf of Mexico. Today, the system is highly managed and impacted by a network of pumps, gates, culve...

Net fluxes (change between upstream and downstream margins) for water, methyl mercury (MeHg), total mercury (THg), dissolved organic carbon (DOC), and chloride (Cl) were assessed twice in an Adirondack stream reach (Sixmile Brook, USA), to test the hypothesized importance of wetland-stream hydraulic and chemical gradients as fundamental controls on...

Chemical reactions occur throughout natural waters however the reaction rates often are enhanced just below the sediment-water interface compared with surface water or deeper groundwater. Hydrologic exchange across the sediment surface brings reactive solutes and fine particulates from surface waters into contact with the abundant reaction sites as...

Sediment flux from in-channel sources can be difficult to accurately quantify due to localized spatial and temporal conditions. Through data collection over multiple years, we can quantify in-channel sediment storage and erosion in the channel bed and margins, which can advance our understanding of channel evolution. Comparison of the sediment flux...

Heterogeneous streambed materials may be expected to develop two general porosity domains: a more-mobile porosity dominated by advective exchange, and a less-mobile porosity dominated by diffusive exchange. Less-mobile porosity containing unique redox conditions or contaminant mass may be invisible to traditional porewater sampling methods, even us...

A growing number of stream-groundwater interface observations reveal the paradox of anaerobic respiration occurring in seemingly oxic-saturated sediments. Here we demonstrate a physical residence time-based explanation for this paradox. Specifically, we show how microzones favorable to anaerobic respiration processes (e.g., denitrification, metal r...

Increasing nitrogen concentrations in the world’s major rivers have led to over-fertilization of sensitive downstream waters1, 2, 3, 4. Flow through channel bed and bank sediments acts to remove riverine nitrogen through microbe-mediated denitrification reactions5, 6, 7, 8, 9, 10. However, little is understood about where in the channel network thi...

Previously regarded as the passive drains of watersheds, over the past 50 years, rivers have progressively been recognized as being actively connected with off channel environments. These connections prolong physical storage and enhance reactive processing to alter water chemistry and downstream transport of materials and energy. Here we propose ri...

Recent observations reveal a paradox of anaerobic respiration occurring in seemingly oxic‐saturated sediments. Here we demonstrate a residence time‐based explanation for this paradox. Specifically, we show how microzones favorable to anaerobic respiration processes (e.g., denitrification, metal reduction, and methanogenesis) can develop in the embe...

Fine sediment is a leading cause of impairment of waterways, but its dynamics are generally poorly understood. Most fingerprinting studies focus on the mineral component of fine sediment, yet the organic fraction has distinct effects on ecosystem processes. Here we employed a novel combination of fluorescence spectroscopy and end-member mixing anal...

Understanding heterogeneity or patchiness in the distribution of vegetation and retention of C and nutrients in river corridors is critical for setting priorities for river management and restoration. Several mechanisms of spatial differentiation in nutrient retention in river and floodplain corridors have been recognized, but few studies have dist...

Groundwater–surface-water (GW-SW) interactions in streams are difficult to quantify because of heterogeneity in hydraulic and reactive processes across a range of spatial and temporal scales. The challenge of quantifying these interactions has led to the development of several techniques, from centimeter-scale probes to whole-system tracers, includ...