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Noah M. Schmadel

Bio: Noah M. Schmadel is an academic researcher from United States Geological Survey. The author has contributed to research in topics: Groundwater & Surface water. The author has an hindex of 15, co-authored 44 publications receiving 557 citations. Previous affiliations of Noah M. Schmadel include Utah State University & Indiana University.

Papers
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Journal ArticleDOI
TL;DR: This article explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a 3-year period spanning pre-and post-beaver colonization.
Abstract: Beaver dams affect hydrologic processes, channel complexity, and stream temperature in part by inundating riparian areas, influencing groundwater–surface water interactions, and changing fluvial processes within stream systems. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a 3-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements, we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach-scale (~ 750 m in length) discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale (ranging from 56 to 185 m in length), the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow, increasing surface and subsurface storage, and increasing groundwater elevations. At the reach scale, temperatures were found to increase by 0.38 °C (3.8 %), which in part is explained by a 230 % increase in mean reach residence time. At the smallest, beaver dam scale (including upstream ponded area, beaver dam structure, and immediate downstream section), there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

81 citations

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TL;DR: In this paper, the authors developed a perceptual model of the river corridor in a headwater mountainous catchment, translate this into a reduced-complexity mechanistic model, and implement the model to examine connectivity and network extent over an entire water year.

76 citations

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TL;DR: Using a metric of reaction significance based on river connectivity, this work provides evidence that intermediate levels of connectivity, rather than the highest or lowest levels, are the most efficient in removing nitrogen from Northeastern United States' rivers.
Abstract: U.S. Geological SurveyUnited States Geological Survey; National Science Foundation Hydrologic Sciences ProgramNational Science Foundation (NSF)NSF - Directorate for Geosciences (GEO); USGS National Water Quality Program; DOE Office of Biological and Environmental Research (BER) in the Subsurface Biogeochemistry Program (SBR) as part of SBR's Scientific Focus Area at the Pacific Northwest National Laboratory (PNNL)

69 citations

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TL;DR: Thresholds in pond density where ponding waters become important features to regional nitrogen removal are identified and shown to vary according to a ponded waters’ relative size, network position, and degree of connectivity to the river network, which suggests worldwide importance of these new metrics.
Abstract: 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 18,000 ponded waters on nitrogen removal through river networks of the Northeastern United States Thresholds in pond density where ponded waters become important features to regional nitrogen removal are identified and shown to vary according to a ponded waters’ relative size, network position, and degree of connectivity to the river network, which suggests worldwide importance of these new metrics Consideration of the interacting physical and biological factors, along with thresholds in connectivity, reveal where, why, and how much ponded waters function differently than streams in removing nitrogen, what regional water quality outcomes may result, and in what capacity management strategies could most effectively achieve desired nitrogen loading reduction

53 citations


Cited by
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TL;DR: In this paper, a review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hypheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to watershed scale.
Abstract: Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed.

644 citations

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TL;DR: In this article, the authors propose river corridor science as a concept that integrates downstream transport with lateral and vertical exchange across interfaces, and include the main channel exchange with recirculating marginal waters, hyporheic exchange, bank storage, and overbank flow onto floodplains under a broad continuum of interactions known as hydrologic exchange flows.
Abstract: 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 river corridor science as a concept that integrates downstream transport with lateral and vertical exchange across interfaces. Thus, the river corridor, rather than the wetted river channel itself, is an increasingly common unit of study. Main channel exchange with recirculating marginal waters, hyporheic exchange, bank storage, and overbank flow onto floodplains are all included under a broad continuum of interactions known as “hydrologic exchange flows.” Hydrologists, geomorphologists, geochemists, and aquatic and terrestrial ecologists are cooperating in studies that reveal the dynamic interactions among hydrologic exchange flows and consequences for water quality improvement, modulation of river metabolism, habitat provision for vegetation, fish, and wildlife, and other valued ecosystem services. The need for better integration of science and management is keenly felt, from testing effectiveness of stream restoration and riparian buffers all the way to reevaluating the definition of the waters of the United States to clarify the regulatory authority under the Clean Water Act. A major challenge for scientists is linking the small-scale physical drivers with their larger-scale fluvial and geomorphic context and ecological consequences. Although the fine scales of field and laboratory studies are best suited to identifying the fundamental physical and biological processes, that understanding must be successfully linked to cumulative effects at watershed to regional and continental scales.

272 citations

Journal ArticleDOI
20 Sep 2019-Science
TL;DR: How flow variability influences long-term persistence of riverine assemblages is demonstrated, and researchers are disentangling the direct effects of flow on communities and ecosystem processes from its indirect effects (e.g., via species interactions, light-blocking turbidity).
Abstract: BACKGROUND Early civilizations developed around seasonal river floodplains, and the natural rhythm of rivers remains critical to humans today. We use streams and rivers to meet drinking water, irrigation, and hydropower needs by storing and moving water in complex ways, at the times and places of our choosing. Consequently, many of Earth’s rivers have flow regimes that are “unnatural” in magnitude, frequency, duration, and timing. The rise in river degradation globally has motivated research on the link between hydrologic alteration and declines in valued biota. At the same time, largely fueled by new technologies and methods, research has expanded to understand the patterns in, and drivers of, riverine processes like primary production, in both near-pristine and degraded rivers. A third line of research, stymied by how difficult it has been to restore degraded rivers, has called for process-based restoration, building on knowledge from the other two research thrusts. Today’s hydroecological science seeks to understand the mechanisms whereby flow regimes affect biota and ecosystem processes, and the interplay between them, in a three-way interaction we call the flow-biota-ecosystem processes nexus. ADVANCES By shifting the focus from static patterns at sites to dynamic processes along river networks, advances are being made to understand the interactions and feedbacks at the nexus. Fueled by increasingly available time-series data and novel modeling, emerging research ranges from studies on regime-based properties such as flow periodicity and its change, to studies on river network structure and associated spatial variation in flow and water chemistry. These studies demonstrate how flow variability influences long-term persistence of riverine assemblages, and they are disentangling the direct effects of flow on communities and ecosystem processes from its indirect effects (e.g., via species interactions, light-blocking turbidity). Changes in temporal patterns in flow magnitudes can increase risk of community collapse and alter key ecosystem processes such as primary production. Growing research shows that storm flows not only enhance inputs and downstream export of terrestrially derived carbon to rivers but, when associated with sustained hydrologic connectivity with soils, exert particular influence on water chemistry and biogeochemical processes that can influence food webs. Increased availability of environmental sensors has stimulated research, showing that extreme flows may impart disproportionate impacts on stream metabolism, but the relationship can depend on the predictability of those flows. Research combining changes in flow patterns with stable isotope analyses is revealing how temporal fluctuations in habitat, and in the quality and quantity of basal resources, influence trophic pathways and resulting food-web structure. Evidence suggests that restoring particular facets of a flow regime can produce desirable conservation outcomes, but context is paramount. Restoration actions going beyond discrete flow events and enhancing groundwater-influenced river habitat or redirecting subsurface flow paths may be critical in future climates. OUTLOOK Our understanding of the flow-biota-ecosystem processes nexus is still incomplete and is a frontier research topic. Challenges include connecting organismal and ecosystem-level processes, and understanding the role of microbial communities as intermediaries. Capturing the effects of watershed-level physical and biogeochemical heterogeneity, and parsing out direct, indirect, or cascading effects of flow alteration on biota and processes would also reduce uncertainty in restoration outcomes, particularly in novel, nonstationary environments. Understanding how much flow restoration alone can achieve in urban watersheds is an urgent need, as is translating findings from hydroecology to design green infrastructure and flow release programs from reservoirs. These management tools may offer growing opportunities to experiment with flow regimes, which will assist in refining process-based river restoration. Both solid science, and effective translation into practice will be needed to curb the fast pace of global river ecosystem degradation.

270 citations

Journal ArticleDOI
TL;DR: A recent review as mentioned in this paper summarizes the existing body of research investigating natural and induced heat transport, and analyzes the progression in fundamental and natural process understanding through the qualitative and quantitative use of heat as a tracer.

163 citations

Journal ArticleDOI
TL;DR: In this article, the authors synthesize the history of hydrological and biogeochemical theory, summarize modern tracer methods, and discuss how improved understanding of flowpath, residence time, and bio-geochemical transformation can help ecohydrology move beyond description of site-specific heterogeneity.

152 citations