Investigations of coupled multiphysics processes in rivers and hyporheic zones have extensively used numerical models. Most existing models use a sequential, one-way coupling between the surface and ...subsurface domains. Such one-way coupling potentially introduces error. To overcome this, a fully coupled model, hyporheicFoam, was developed using the open-source computational platform OpenFOAM. It captures the coupled flow and multicomponent reactive transport processes within both surface and subsurface domains and across their interface. Here, the coupling between two domains is implemented by mapping conservative flux boundary conditions at the interface through an iterative algorithm. Reactive transport is enabled by specifying a reaction network. To start, we have implemented reaction kinetics following the double Monod-type model with inhibition. The model capability is illustrated through modeling of both conservative and reactive hyporheic flow and transport through dune bedforms. With the novel coupled model, it is now possible to quantify reactions wherein the reactants and products are constantly exchanging between domains and have feedbacks. hyporheicFoam can simulate large, three-dimensional cases owing to the computational flexibility and power offered by the code structure and parallel design of OpenFOAM.
The Natural Wood Regime in Rivers WOHL, ELLEN; KRAMER, NATALIE; RUIZ-VILLANUEVA, VIRGINIA ...
Bioscience,
04/2019, Volume:
69, Issue:
4
Journal Article
Peer reviewed
Open access
The natural wood regime forms the third leg of a tripod of physical processes that supports river science and management, along with the natural flow and sediment regimes. The wood regime consists of ...wood recruitment, transport, and storage in river corridors. Each of these components can be characterized in terms of magnitude, frequency, rate, timing, duration, and mode. We distinguish the natural wood regime, which occurs where human activities do not significantly alter the wood regime, and a target wood regime, in which management emphasizes wood recruitment, transport, and storage that balance desired geomorphic and ecological characteristics with mitigation of wood-related hazards. Wood regimes vary across space and through time but can be inferred and quantified via direct measurements, reference sites, historical information, and numerical modeling. Classifying wood regimes with respect to wood process domains and quantifying the wood budget are valuable tools for assessing and managing rivers.
Hyporheic zones (HZs)–zones of groundwater–surface water mixing–are hotspots for dissolved organic matter (DOM) and nutrient cycling that can disproportionately impact aquatic ecosystem functions. ...However, the mechanisms affecting DOM metabolism through space and time in HZs remain poorly understood. To resolve this gap, we investigate a recently proposed theory describing trade-offs between carbon (C) and nitrogen (N) limitations as a key regulator of HZ metabolism. We propose that throughout the extent of the HZ, a single process like aerobic respiration (AR) can be limited by both DOM thermodynamics and N content due to highly variable C/N ratios over short distances (centimeter scale). To investigate this theory, we used a large flume, continuous optode measurements of dissolved oxygen (DO), and spatially and temporally resolved molecular analysis of DOM. Carbon and N limitations were inferred from changes in the elemental stoichiometric ratio. We show sequential, depth-stratified relationships of DO with DOM thermodynamics and organic N that change across centimeter scales. In the shallow HZ with low C/N, DO was associated with the thermodynamics of DOM, while deeper in the HZ with higher C/N, DO was associated with inferred biochemical reactions involving organic N. Collectively, our results suggest that there are multiple competing processes that limit AR in the HZ. In conclusion, resolving this spatiotemporal variation could improve predictions from mechanistic models, either via more highly resolved grid cells or by representing AR colimitation by DOM thermodynamics and organic N.
Bagmati River is considered a potential biodiversity conservation area due to its unique and diversified habitat in urban area. However, little information is available on the bird diversity, their ...abundance and factor affecting on bird species. We aimed to explore the bird diversity and factors affecting their abundance along the Bagmati River corridor in urban areas of Nepal. This study generated data using a point count method along the Bagmati River corridor between October 2021 and April 2022. We identified 67 bird species belonging to 11 orders and 28 families. Passeriformes and Muscicapidae were the most prevalent orders and families among the birds that were observed. Among the feeding guilds, insectivore birds were recorded as the highest bird species and followed by omnivores, carnivores, frugivores and granivores. The Shannon-Wiener diversity index of bird species was 3.35, while the Pielou's evenness index was 0.796. The bird abundance was increased in presence of tree, near the settlement, nearer to sewage, at low temperatures, increasing distance to water source and road whereas decreased with the distance to open land and at a higher elevation. Bagmati River corridor at urban area is rich in biodiversity as it supports more number of various bird species and their abundance is affected by presence of tree, distance to the water source, road, settlement, open land, sewage, temperature and elevation. Thus, knowledge on the conservation of habitat and minimizing the factors that affect the bird's abundance helps in protecting the status of avian species by developing site specific conservation action plan.
Glacier retreat is rapidly transforming some watersheds, with ramifications for water supply, ecological succession, important species such as Pacific salmon (Oncorhynchus spp.), and cultural uses of ...landscapes. To advance a more holistic understanding of the evolution of proglacial landscapes, we integrate multiple lines of knowledge starting in the early 1900s with contemporary data from the Taaltsux̱éi (Tulsequah) Watershed in British Columbia, Canada. Our objectives were to: 1) synthesize recent historical geography and Indigenous Knowledge, including glacier dynamics, and hydrology; 2) describe the limnology of a proglacial lake; 3) quantify decadal-scale downstream physical floodplain change; and 4) characterize riverine physical, chemical, and biological differences relative to distance from the proglacial lake. Since 1982, the Tulsequah Glacier has receded 0.07 km/yr, exposing a cold, deep, and growing proglacial lake. The downstream floodplain is rapidly changing; satellite imagery analysis revealed a 14 % increase in vegetation from 2003 to 2017 and Indigenous Knowledge described increases in vegetation and wildlife habitat over the last century. Contemporary measurements of physical-chemical water properties differed across sites representing the upper and lower watershed, and mainstem and off-channel habitats. Catches of juvenile salmonids in the upper watershed (closer to the glacier) were mostly limited to warmer, clearer groundwater-fed channels, whereas in the lower watershed there were salmonids in both groundwater-fed and mainstem habitats. There was limited zooplankton taxa diversity from the proglacial lake and benthic macroinvertebrates in the river. Collectively, our synthesis suggests that the transformation of proglacial landscapes experiencing rapid ice loss can be influenced by interlinked abiotic processes of glacier retreat, lake formation, and altered hydrology, as well as corresponding biological processes such as beaver repopulation, wetland formation, and riparian vegetation growth. These factors, along with expected increases to proglacial lake productivity and salmon habitat suitability, are an important consideration for forward-looking watershed management of glacier-fed rivers.
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•Evolving proglacial lake watersheds link to biodiversity and societal needs.•We combined historical geography, Indigenous Knowledge, and contemporary analysis.•Physical-chemical and biological diversity unfolds at the stream-reach scale.•Ice retreat presents opportunities for increased biological productivity downstream.•Studies of proglacial landscapes are urgent as these ecosystems face rapid change.
River corridors, acknowledged as "blue-green infrastructure," have gained increasing attention due to their potential benefits on individual quality of life and social well-being in urban areas. ...However, there remains a lack of a comprehensive synthesis of evidence through a systematic literature review on the usage and associated constraints of urban river corridors. The paper aims to systematically review those attributes that influence the usage of urban river corridors and to analyse their complex interactions from a socio-ecological perspective. Results comprise an overview of the reviewed literature, including authorship, journal, geographical distribution, sample characteristics, data collection and analysis methods, and critical findings. Fifty-nine peer-reviewed papers published between 2012 and 2023 met the authors' inclusion criteria. The findings highlight the significant influence of individual, social, and physical factors on the usage of urban river corridors. Additionally, time reason also impact users' decisions regarding the usage of urban river corridors. Finally, a conceptual framework was proposed to guide urban planners, designers, and policymakers in enhancing urban river corridors' design and management standards, ultimately creating a sustainable, resilient, and inclusive leisure space catering to diverse needs.
Flow discharge and anthropogenic activities influence the composition and configuration of habitat patches in river ecosystems. Understanding the response of habitat landscapes and the corresponding ...fish habitat quality is crucial for river management. We investigated the reaction of fish habitat suitability and variant flow discharge performance in examining aquatic habitat patch fragmentation. The hydraulic simulation and fish habitat calculation were used to determine the flow characteristics, habitat conditions, and river landscapes. FRAGSTATS was applied to explore the composition and configuration of habitat patches. Cluster analysis and logistic regression were employed to compute the spatiotemporal variabilities of riverscape indices and establish the relationship between riverscape attributes and fish habitat quality. The results indicate that the changes in specific habitat features are associated with the riverscape indices of total edge (TE), mean nearest-neighbor distance (MNN), interspersion and juxtaposition index (IJI), mean patch size (MPS), and area-weighted mean patch fractal dimension (AWMPFD). The flow discharge is the key to determining habitat fragmentation in rivers, with natural barriers occurring at low flow. In contrast, weirs are anthropogenic obstacles that have significant adverse effects on the downstream corridor. A priority restoration activity to conserve river habitat is to create refuge pools during dry seasons by modifying channel morphology. The positive correlation between habitat suitability and MPS and the negative relationship between habitat suitability and AWMPFD highlight the patch size and shape complexity that are critical indices for pool creation. The prediction of the landscape attributes of the outcomes under different scenarios could support the decision-making in river management. The innovative integrated method presented in this study provides a solid foundation and supports the implementation of nature-based solutions for sustainable river management.
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•A novel river habitat management model for fish was established.•Changes with the specific habitat features are evidenced with the riverscape indices.•Low flow discharge and weirs disconnect habitat patches and disrupt river corridors.•Restoration priority is to create refuge pools for endemic fishes during dry seasons.•Patch size and shape complexity are the critical indices for the pool creation.
Changes in forest extent in the corridors of four rivers of the Polish Carpathians over the last 130 years and their relation to changes in planform river geometry were investigated through the ...analysis of 1:25000-scale maps from the 1870s and aerial images from the mid-20th century and 2009. Average proportions of river and its geomorphic units as well as floodplain and its land cover features in the total width/area of the analysed river corridors were determined and compared between the three dates. All the analysed rivers narrowed significantly over the study period. This increased considerably the proportion of floodplains in the area of the river corridors, while lateral parts of the former, wide channels became a place of forest development. In the Koszarawa and Raba valleys, forest developed also on parts of the former floodplains following a decline in agricultural and pastoral use of lands with shallow, poor soils. The proportion of forest in the total area of the river corridors increased from 0–7.5% in the 1870s to 28.5–46.5% in 2009, and the forest expansion was mainly driven by the timing and scale of channelization works that reclaimed parts of the former channels from the rivers. A reduction in flow and sediment dynamics of Carpathian rivers over the 20th century enabled development of islands in their active zones. However, channelization works eliminated islands from most river reaches and thus islands persisted only in scarce unmanaged reaches. The expansion of floodplain forests in Carpathian valleys improves functioning of the river ecosystems but the resultant increased delivery of large wood to river channels may generate flood hazard. Optimal river management should avoid removal of riparian trees to maximize the environmental benefits but enable undisturbed transfer of driftwood through bridge cross-sections to minimize the flood hazard resulting from floodplain forest development.
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•We examined changes in the extent of floodplain forest and their relation to channel changes of Polish Carpathian rivers.•Corridors of four rivers presented on historical maps and aerial photos from the last 130 years were analysed.•Forest developed on lateral parts of the former, wide channels narrowed in the course of river channelization.•In the 20th century islands developed in unmanaged river reaches and were eliminated from channelized reaches.•Floodplain forests exert a beneficial influence on the river ecosystems but are also a source of flood hazard.
•Implementation of a mechanistic, dynamic model of network expansion and contraction.•Importance of geologic setting and hydrologic forcing change through a water year.•Network expansion is ...insensitive to hydrologic forcing under wet conditions.•Geologic setting matters most under low and moderate discharge conditions.•Prediction of channel network dynamics may inform management of river corridors.
Headwater stream networks expand and contract in response to changes in stream discharge. The changes in the extent of the stream network are also controlled by geologic or geomorphic setting – some reaches go dry even under relatively wet conditions, other reaches remain flowing under relatively dry conditions. While such patterns are well recognized, we currently lack tools to predict the extent of the stream network and the times and locations where the network is dry within large river networks. Here, we develop 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. Our model agreed reasonably well with our observations, showing that the extent and connectivity of the river network was most sensitive to hydrologic forcing under the lowest discharges (Qgauge < 1 L s−1), that at intermediate discharges (1 L s−1 < Qgauge < 10 L s−1) the extent of the network changed dramatically with changes in discharge, and that under wet conditions (Qgauge > 10 L s−1) the extent of the network was relatively insensitive to hydrologic forcing and was instead determined by the network topology. We do not expect that the specific thresholds observed in this study would be transferable to other catchments with different geology, topology, or hydrologic forcing. However, we expect that the general pattern should be robust: the dominant controls will shift from hydrologic forcing to geologic setting as discharge increases. Furthermore, our method is readily transferable as the model can be applied with minimal data requirements (a single stream gauge, a digital terrain model, and estimates of hydrogeologic properties) to estimate flow duration or connectivity along the river corridor in unstudied catchments. As the available information increases, the model could be better calibrated to match site-specific observations of network extent, locations of dry reaches, or solute break through curves as demonstrated in this study. Based on the low initial data requirements and ability to later tune the model to a specific site, we suggest example applications of this parsimonious model that may prove useful to both researchers and managers.
Fine particles are critical to stream ecosystem functioning, influencing in-stream processes from pathogen transmission to carbon cycling, all of which depend on particle immobilization. However, our ...ability to predict particle immobilization is limited by (1) availability of combined solute and particle tracer data and (2) identifying parameters that appropriately represent fine particle immobilization, due to the myriad of objective functions and model formulations. We found that improved predictions of the full distribution of possible fine particle residence times requires using an objective function that assesses both the peak and tailing of breakthrough curves together with solute tracers to constrain in-stream transport processes. The representation of immobilization processes was significantly improved when solute tracer data were combined with a particle model, starkly contrasting the common assumption that fine particles transport as washload. We develop a clear strategy for improving fine particle transport predictions, reshaping the potential role of fine particles in water quality management.
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