Stream solute tracers are commonly injected to assess transport and transformation in study reaches, but results are biased toward the shortest and fastest storage locations. While this bias has been ...understood for decades, the impact of an experimental constraint on our understanding has yet to be considered. Here, we ask how different our understanding of reach‐ and segment‐scale transport would be if our empirical limits were extended. We demonstrate a novel approach to manipulate experimental conditions and observe mass that is stored at timescales beyond the traditional reach‐scale window of detection. We are able to explain the fate of an average of 26% of solute tracer mass that would have been considered as “lost” in a traditional study design across our 14 replicates, extending our detection limits to characterize flowpaths that would have been previously unmeasured. We demonstrate how this formerly lost mass leads to predicting lower magnitudes of gross gains and losses in individual reaches, and ultimately show that the network turnover we infer from solute tracers represents an upper limit on actual, expected behavior. Finally, we review the evolution of tracer studies and their interpretation including this approach and provide a proposed future direction to extend empirical studies to not‐before‐seen timescales.
Key Points
With careful design, solute tracer studies can be used to assess the fate of solute mass along flowpaths that would not normally be detected
Extended mass recovery allows us to understand the formerly unknown fate of more than 26% of all lost tracer mass
Accounting for mass recovery beyond the typical window of detection reduced inferred channel water turnover, changing interpreted spatial sources of gains
The success of river restoration was estimated using the ecosystem services approach. In eight pairs of restored–unrestored reaches and floodplains across Europe, we quantified provisioning ...(agricultural products, wood, reed for thatching, infiltrated drinking water), regulating (flooding and drainage, nutrient retention, carbon sequestration) and cultural (recreational hunting and fishing, kayaking, biodiversity conservation, appreciation of scenic landscapes) services for separate habitats within each reach, and summed these to annual economic value normalized per reach area. We used locally available data and literature, did surveys among inhabitants and visitors, and used a range of economic methods (market value, shadow price, replacement cost, avoided damage, willingness-to-pay survey, choice experiment) to provide final monetary service estimates. Total ecosystem service value was significantly increased in the restored reaches (difference 1400 ± 600 € ha⁻¹ year⁻¹; 2500 − 1100, p = 0.03, paired t test). Removal of one extreme case did not affect this outcome. We analysed the relation between services delivered and with floodplain and catchment characteristics after reducing these 23 variables to four principal components explaining 80% of the variance. Cultural and regulating services correlated positively with human population density, cattle density and agricultural N surplus in the catchment, but not with the fraction of arable land or forest, floodplain slope, mean river discharge or GDP. Our interpretation is that landscape appreciation and flood risk alleviation are a function of human population density, but not wealth, in areas where dairy farming is the prime form of agriculture.
The urban river corridor is an important ecological space that is known for its landscapes and ecological continuity. Compared with the natural river, the urban river is seriously affected by human ...activities, which are constructed with the hope of recreating a similar natural environment and are uniquely designed so that ecological specialists, landscape experts and scientists could study both the surrounding environment's ecological effects and the continuity degree of the river corridor area. A system, including 10 indices urban river corridor, is established. This assessment method adapts the Analytic Hierarchy Process, GIS data analysis and GIS space technology, and is combined with these methods based on quantitative and qualitative analyses. Using the results obtained by studying the Suzhou River Corridor and the assessment of ecological continuity is completed and the spatial distribution characteristics are approved, thus it allows future development throughout the corridor. Eventually, a development policy is proposed. Firstly, a method to improve the landscape connectivity among the river's greenways is needed. Secondly, a high value area with ecological continuity related to the river greenway is planned along the river greenway. Thirdly, a sufficient natural area is needed to give the area a river corridor influence, maintain the river's ecological continuity, and keep this natural area undisturbed by zoning. Lastly, the plant species distribution need to link ecological traits and landscape matrix. The study of this assessment method provides a rational development path and decision-making basis for the construction of healthy and sustainable urban river corridors.
•An index system for the ecological continuity of urban stream corridor areas was identified.•A methodology for assessing the ecological continuity of urban stream corridors from a landscape perspective was proposed.•The development polices in the landscape spatial assessment process were integrated into the case study.
In this work, a well-characterized field site along a major river corridor was used to investigate the dynamic pathways and impacts of subsurface hydrogeologic structures on kilometer-scale ...hydrologic exchange flows between river water and groundwater. A aqueous uranium (Uaq) plume exists at the site that discharges to the Columbia River. We performed temporally intensive monitoring of specific conductance (SpC) and Uaq concentrations within the plume at increasing distances from the river shoreline and at locations both within and outside a presumed subsurface pathway of lateral hydrologic exchange. Specific conductance and Uaq were utilized as in-situ tracers of hydrologic exchange and associated groundwater-surface water mixing. Monitoring data was collected for an approximate two year period during which seasonal river elevations varied by more than 2 m causing distinct events of river water intrusion and retreat from the near-shore aquifer, and large temporal variations in well-water analyte concentrations. Statistical clustering analysis was applied to identify well groupings exhibiting common time series behaviors. PFLOTRAN was implemented within a modeling domain of 3.3 x 1.9 km with dynamic flow boundary conditions and accurate subsurface topography for the basal aquitard underlying the aquifer. In-silico calculations of river water tracer behavior were performed to assess predominant flow directions and velocities influenced by river stage variations and variable aquitard topography, and their collective influences on SpC and Uaq concentrations. We demonstrate complicated multidirectional flow behaviors at the kilometer scale resulting from hydrologic exchange and subsurface structure that influence plume dynamics and determine the overall system behavior.
•Development patterns of urban riverside public spaces are briefly analyzed.•Riverfront parks and walks are classified within a socioecological perspective.•Three main types of open spaces are ...described: floodplain, upland and raised.•The application of the classification is useful to characterize public riverfronts.•The identification of classes allows an analysis of public use on riverfronts.
Since the seventies, cities all over the world are rediscovering their rivers. Recreational uses of the urban streams are becoming popular and public access to the waterfronts is being improved. This has led to the construction of a wide variety of public open spaces on the riverfront with different ways of interacting with the river ecosystem.
In this research, we elaborate a classification of riverfront parks and walks based on two criteria: the position of the open space within the river corridor and the access possibilities from the open space to the water. To verify the applicability of the classification framework, seven Spanish urban rivers have been studied.
Results derived from the classification process show that public recreational riverfronts can be categorized into three classes: floodplain, upland and raised spaces. Within the floodplain spaces, fluvial subclass can be distinguished from riparian subclass in that the former allows greater access to water. The case study confirms the viability of the classification system and it is useful to describe the open space classes.
We found that, despite their spatial characteristics, design and use can be almost unlimited, there are patterns associated with each class. The methodology developed and its application (1) allows to know the amount of public spaces in the urban river corridor, (2) gives an organizing framework for understanding river-city recreational interactions and (3) facilitates the assessment of the ecological state of the riverbanks.
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, ecology, and biogeochemistry. We then summarize contemporary models of the river corridor along multiple axes including dimensions of space and time, disturbance regimes, connectivity, hydrochemical exchange flows, and legacy effects of humans. We explore how river corridor science can be advanced with a critical zone framework by moving beyond a primary focus on discharge-based controls toward multi-factor models that identify dominant processes and thresholds that make predictions that serve society. We then identify opportunities to investigate relationships between large-scale spatial gradients and local-scale processes, embrace that riverine processes are temporally variable and interacting, acknowledge that river corridor processes and services do not respect disciplinary boundaries and increasingly need integrated multidisciplinary investigations, and explicitly integrate humans and their management actions as part of the river corridor. We intend our review to stimulate cross-disciplinary research while recognizing that river corridors occupy a unique position on the Earth's surface.
Recent predictions of hyporheic exchange at the basin-scale assume individual features control exchange independently of each other, which has been demonstrated in relatively uniform, low-gradient ...rivers. However, this assumption may not hold in steep catchments where both the type and size of individual features may vary over short distances, leading to irregular patterns of feature dominance on hyporheic exchange flows. Also, steep longitudinal gradients support substantial downvalley flows in the subsurface, which may create feedbacks between adjacent features. In this study, we test the extent to which features interact with one another and whether they can be aggregated to make reach-scale predictions in a headwater mountain stream. Using systematic manipulations of a 2-D stream centerline model and spectral analyses, we test for the presence of both feature-feature and multiscale interactions. Our results show that changing the height of individual step-pool features can alter hyporheic flow fields in neighboring, and sometimes distant, features. Spectral analyses revealed two scales of streambed topography—a local scale of single features and an intermediate scale that spanned multiple local-scale features. All features produced hyporheic exchange, but turnover of deeper hyporheic water only occurred at a few key locations where local- and intermediate-scale features amplified each other. Further, shallow bedrock increases the ratio of local- and intermediate-scale flowpaths to regional-scale flowpaths. Conceptual models portraying hyporheic exchange as a series of nested flowpaths should include the interactions among streambed topographic features in mountain streams. These results have implications for upscaling, field experiments, and stream restoration in steep catchments.
Phosphorus in the river corridor Records, Rosemary M.; Wohl, Ellen; Arabi, Mazdak
Earth-science reviews,
July 2016, 2016-07-00, 20160701, Volume:
158
Journal Article
Peer reviewed
Open access
River corridor protection has been adopted by government agencies and non-governmental organizations to try to control nonpoint nutrient loading to rivers. Yet, river corridor protection and modeling ...strategies developed on a national basis may not fully account for dynamics that have proven to be important controls on phosphorus in river corridors. These sources of uncertainty may have economic and environmental costs, yet we know of no previous works that have proposed a broad conceptual model of phosphorus dynamics in river corridors. In this review, we develop a conceptual model of phosphorus in the river corridor under natural conditions based on existing research by: (i) evaluating how processes and controls vary among distinct landscape characteristics and among distinct segments within river networks (e.g., in confined channels versus wide valleys); and (ii) determining whether some processes and controls are generally more dominant for some landscape types and river reaches. Finally, we provide an example application of the conceptual model, and identify key areas for future research. The review suggests that phosphorus dynamics in the river corridor, and their controls, may vary substantially across different landscape types and river reaches. However, the conceptual model outlined here illustrates how certain characteristics of landscape type, and abundance, transport, and transformation of phosphorus and reactive compounds, may help to predict important river corridor phosphorus dynamics. Use of this conceptual model can better inform numerical modeling of phosphorus dynamics and management of river corridors.
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