Journal articles on the topic 'Riverine flow conditions'
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1
Tang, Jian, Xinan Yin, ChunXue Yu, and Zhifeng Yang. "Suitable Environmental Flow Release Criteria for Both Human and Riverine Ecosystems: Accounting for the Uncertainty of Flows." Mathematical Problems in Engineering 2012 (2012): 1–14. http://dx.doi.org/10.1155/2012/704989.
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Environmental flow (e-flow) release criteria are key parameters in water resources management and riverine ecosystem protection. The previous methods for e-flow criterion determination are based on the historical flow time series without the consideration of flow uncertainty. Due to low possibility of reoccurrence of the historical flows and the uncertainty of future flows, the flow uncertainty needs to be integrated in the process of determining e-flow release criteria. In this research, a new method is proposed to determine the optimal e-flow release criteria under flow uncertainty accounting for both the human and riverine ecosystem needs. In the new method, the scenario tree method is applied to generate the scenarios of flows, which can cover most of possible flow conditions and can effectively reflect the uncertainty of flows; the Range of Variability Approach (RVA), a most commonly used method to assess the flow regime alteration, is refined by incorporating the uncertainty of flows. The Tang River in Northern China is taken as a case study to test the effectiveness of the new method. The results show that the previous method obviously overestimates the optimal e-flow release criteria and the new method can get more suitable criteria that are suitable for both human and riverine ecosystems.
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Kumar, Rakesh, Prabhakar Sharma, Anurag Verma, Prakash Kumar Jha, Prabhakar Singh, Pankaj Kumar Gupta, Ravish Chandra, and P. V. Vara Prasad. "Effect of Physical Characteristics and Hydrodynamic Conditions on Transport and Deposition of Microplastics in Riverine Ecosystem." Water 13, no. 19 (September 30, 2021): 2710. http://dx.doi.org/10.3390/w13192710.
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Microplastic disposal into riverine ecosystems is an emergent ecological hazard that mainly originated from land-based sources. This paper presents a comprehensive review on physical processes involved in microplastics transport in riverine ecosystems. Microplastic transport is governed by physical characteristics (e.g., plastic particle density, shape, and size) and hydrodynamics (e.g., laminar and turbulent flow conditions). High-density microplastics are likely to prevail near riverbeds, whereas low-density particles float over river surfaces. Microplastic transport occurs either due to gravity-driven (vertical transport) or settling (horizontal transport) in river ecosystems. Microplastics are subjected to various natural phenomena such as suspension, deposition, detachment, resuspension, and translocation during transport processes. Limited information is available on settling and rising velocities for various polymeric plastic particles. Therefore, this paper highlights how appropriately empirical transport models explain vertical and horizontal distribution of microplastic in riverine ecosystems. Microplastics interact, and thus feedback loops within the environment govern their fate, particularly as these ecosystems are under increasing biodiversity loss and climate change threat. This review provides outlines for fate and transport of microplastics in riverine ecosystems, which will help scientists, policymakers, and stakeholders in better monitoring and mitigating microplastics pollution.
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Humphries, Paul, Alison King, Nicole McCasker, R. Keller Kopf, Rick Stoffels, Brenton Zampatti, and Amina Price. "Riverscape recruitment: a conceptual synthesis of drivers of fish recruitment in rivers." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 2 (February 2020): 213–25. http://dx.doi.org/10.1139/cjfas-2018-0138.
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Most fish recruitment models consider only one or a few drivers in isolation, rarely include species’ traits, and have limited relevance to riverine environments. Despite their diversity, riverine fishes share sufficient characteristics that prediction of recruitment should be possible. Here we synthesize the essential components of fish recruitment hypotheses and the key features of rivers to develop a model that predicts relative recruitment strength, for all fishes, in rivers under all flow conditions. The model proposes that interactions between flow and physical complexity will create locations in rivers, at mesoscales, where energy and nutrients are enriched. The resultant production of small prey will be concentrated and prey and fish larvae located (through dispersal or retention) so that the larvae can feed, grow, and recruit. Our synthesis explains how flow and physical complexity affect fish recruitment and provides a conceptual basis to better conserve and manage riverine fishes globally.
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RICHARDSON, ADAM, and PAUL HUMPHRIES. "Reproductive traits of riverine shrimps may explain the impact of altered flow conditions." Freshwater Biology 55, no. 10 (June 9, 2010): 2011–22. http://dx.doi.org/10.1111/j.1365-2427.2010.02457.x.
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Horne, Avril C., Rory Nathan, N. LeRoy Poff, Nick R. Bond, J. Angus Webb, Jun Wang, and Andrew John. "Modeling Flow-Ecology Responses in the Anthropocene: Challenges for Sustainable Riverine Management." BioScience 69, no. 10 (September 4, 2019): 789–99. http://dx.doi.org/10.1093/biosci/biz087.
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Abstract Climate change will increase water stress in many regions placing greater pressures on rivers to meet human and ecological water needs. Managing rivers experiencing water stress requires a fundamental understanding of how ecosystem processes and functions respond to natural and anthropogenic drivers of flow variability and change. The field of environmental flows meets this need by defining “flow-ecology” relationships—mathematical models linking ecological characteristics and dynamics to the underlying flow regime. However, because these relationships are most often based on historical hydrologic regimes, they implicitly assume climatic stationarity. A fundamental challenge in the Anthropocene is how to model flow-ecology relationships such that the effects of nonstationarity can be captured. In the present article, we introduce a novel approach that addresses these shortcomings and show its utility through a series of conceptual and empirical examples. The framework incorporates ecological dynamics and uncertain future hydrologic conditions, as well as nonstationarity itself, thereby providing a viable framework for modeling flow-ecology responses to inform water management in a rapidly changing climate.
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Ren, Kang, Shengzhi Huang, Qiang Huang, Hao Wang, and Guoyong Leng. "Environmental Flow Assessment Considering Inter- and Intra-Annual Streamflow Variability under the Context of Non-Stationarity." Water 10, no. 12 (November 26, 2018): 1737. http://dx.doi.org/10.3390/w10121737.
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A key challenge to environmental flow assessment in many rivers is to evaluate how much of the discharge flow should be retained in the river in order to maintain the integrity and valued features of riverine ecosystems. With the increasing impact of climate change and human activities on riverine ecosystems, the natural flow regime paradigm in many rivers has become non-stationary conditions, which is a new challenge to the assessment of environmental flow. This study presents a useful framework to (1) detect change points in runoff time series using two statistical methods (Mann-Kendall test method and heuristic segmentation method), (2) adjust data of the changed period against the original flow series into a stationary condition using a procedure of reconstruction; and (3) incorporate inter- and intra-annual streamflow variability with adjusted streamflow to evaluate environmental flow. The Jialing to Han inter-basin water transfer project was selected as the case study. Results indicate that a change point of 1994 was identified, revealing that the stationarity of annual streamflow series is invalid. The variations of reconstructed streamflow series are roughly consistent with original streamflow series, especially in the maximum/minimum values and rise/fall rates, but the mean value of reconstructed streamflow series is increased. The reconstructed streamflow series would further serve to eliminate the non-stationary of original streamflow, and incorporating the inter- and intra-annual variability would upgrade the ecosystem fitness. Selecting different criteria for the conservation of riverine ecosystems can have significantly different consequences, and we should not focus on the protection of specific objectives that will inevitably affect other aspects. This study provides a useful framework for environmental flow assessment and can be applied to a wide range of instream flow management approaches to protect the riverine ecosystem.
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Rosa, Eric, Claude Hillaire-Marcel, Bassam Ghaleb, and Terry A. Dick. "Environmental and seasonal controls on riverine dissolved uranium in the Hudson, James, and Ungava bays region, Canada." Canadian Journal of Earth Sciences 49, no. 6 (June 2012): 758–71. http://dx.doi.org/10.1139/e2012-025.
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This study documents the spatiotemporal variability of riverine uranium contents and fluxes in rivers discharging into the Hudson, James, and Ungava bays (HJUB). Samples retrieved during a monitoring program of the Koksoak, Great Whale, La Grande, and Nelson rivers were analyzed for dissolved uranium concentration [U] and activity ratio (234U/238U). Field surveys conducted during baseflow and snowmelt in six other rivers of the HJUB basin provided complementary data. It is estimated that altogether, the studied rivers export 3.4 × 105 mol/year of U towards the HJUB, with a discharge weighted average (234U/238U) of 1.27. Two main factors appear to control seasonal fluctuations in dissolved U exports from HJUB rivers: snowmelt and anthropogenic flow control. Under natural hydrological regimes, the dilution of U caused by snowmelt does not compensate for the associated increase in discharge, and riverine U fluxes are intensified during springtime. Contrastingly, the timing of riverine U exports is decoupled from hydroclimatic conditions in rivers affected by flow-control structures. Despite the seasonal variations in riverine U contents, the sampling profiles carried along two of the monitored rivers reveal that within the study region, sample locality is at least as important as sampling time for evaluating riverine U fluxes. In addition, a compilation of data from North American rivers reveals that spatial variations in riverine U contents seem to respond to a prominent lithological control, as rivers draining sedimentary rocks (with abundant carbonates) tend to present overall higher U contents and lower (234U/238U) variability than the rivers of the Canadian Shield.
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Townsend, S. A., M. Przybylska, and M. Miloshis. "Phytoplankton composition and constraints to biomass in the middle reaches of an Australian tropical river during base flow." Marine and Freshwater Research 63, no. 1 (2012): 48. http://dx.doi.org/10.1071/mf11111.
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Under high flows, the biomass of riverine phytoplankton can be constrained by short transport times and advective losses. However, under slower flows and longer transport times, secondary factors and sometimes their interaction with flow may constrain phytoplankton biomass. To contribute to a wider understanding of the riverine conditions that constrain phytoplankton biomass, we tested the hypothesis that phytoplankton of the Daly River (tropical Australia) was constrained by transport time during dry-season base flow. The river is virtually undisturbed, with oligotrophic nutrient concentrations during the dry season. The most frequently occurring taxa were planktonic, rather than benthic, and dominated by the dinoflagellate Peridinium inconspicuum which has r-strategist traits that favour rapid growth in a nutrient-deficient environment. Our hypothesis was not supported because increased downstream loads of Chlorophyll a and the domination of P. inconspicuum inferred phytoplankton net growth. Instead, phytoplankton biomass was more likely to be nutrient-limited, although transport time may limit phytoplankton growth over some reaches and for specific taxa. The present study demonstrated that even in the fast-flowing middle reaches of a river (~0.4 m s–1), a population of phytoplankton can be sustained.
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Li, Junhua, Mingwu Zhang, Enhui Jiang, Li Pan, Aoxue Wang, Yafei Wang, and Shengqi Jian. "Influence of Floodplain Flooding on Channel Siltation Adjustment under the Effect of Vegetation on a Meandering Riverine Beach." Water 13, no. 10 (May 18, 2021): 1402. http://dx.doi.org/10.3390/w13101402.
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Flooding in a sediment-laden floodplain is affected by riverine beach vegetation and the shape of a meandering compound channel. The laws of water and sediment exchange and the deposition distribution in beach troughs are very complex. These factors play a significant role in the formation and development of secondary suspended rivers, in the adjustment of the beach horizontal gradient, and even in the evolution of the flood control situation. In this study, we used a combination of experimental simulation and theoretical research to carry out a generalized model test of floodplain flooding evolution, analyzed the lateral distribution characteristics of sediment-laden flow and sediment factors in a meandering compound channel under the conditions of beach vegetation, and revealed the pros and cons of beach vegetation on the adjustment of the beach and channel siltation. The model test results of the flooding in the floodplain in the compound channel with meandering vegetation showed that the main stream was not only concentrated in the main channel but also appeared near the foot of the left and right bank levees and formed flood discharges along the embankment. As the riverine beach siltation was mainly concentrated at the riverine beach lip, the vegetation on the riverine beach had a significant effect on slowing down the flow velocity. Whether it was a row or full vegetation on both sides of the bank, this played an important role in the stability of the main channel. When there was no vegetation on the riverine beach, the main channel was easy to move. The arrangement of full vegetation on the riverine beach had a uniform effect on the velocity distribution of the riverine beach, which reduced the phenomenon of excessive velocity at the foot of the riverine beach and increased the velocity effect in the main channel. These results will provide a theoretical basis for the utilization of riverine beach areas and river management in the lower Yellow River and have a great significance for enriching the basic theory of water and sediment movement and promoting the integration of hydraulics, river dynamics, and ecology.
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Bruce, L. C., P. L. M. Cook, I. Teakle, and M. R. Hipsey. "Hydrodynamic controls on oxygen dynamics in a riverine salt wedge estuary, the Yarra River estuary, Australia." Hydrology and Earth System Sciences 18, no. 4 (April 10, 2014): 1397–411. http://dx.doi.org/10.5194/hess-18-1397-2014.
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Abstract. Oxygen depletion in coastal and estuarine waters has been increasing rapidly around the globe over the past several decades, leading to decline in water quality and ecological health. In this study we apply a numerical model to understand how salt wedge dynamics, changes in river flow and temperature together control oxygen depletion in a micro-tidal riverine estuary, the Yarra River estuary, Australia. Coupled physical–biogeochemical models have been previously applied to study how hydrodynamics impact upon seasonal hypoxia; however, their application to relatively shallow, narrow riverine estuaries with highly transient patterns of river inputs and sporadic periods of oxygen depletion has remained challenging, largely due to difficulty in accurately simulating salt wedge dynamics in morphologically complex areas. In this study we overcome this issue through application of a flexible mesh 3-D hydrodynamic–biogeochemical model in order to predict the extent of salt wedge intrusion and consequent patterns of oxygen depletion. The extent of the salt wedge responded quickly to the sporadic riverine flows, with the strength of stratification and vertical density gradients heavily influenced by morphological features corresponding to shallow points in regions of tight curvature ("horseshoe" bends). The spatiotemporal patterns of stratification led to the emergence of two "hot spots" of anoxia, the first downstream of a shallow region of tight curvature and the second downstream of a sill. Whilst these areas corresponded to regions of intense stratification, it was found that antecedent conditions related to the placement of the salt wedge played a major role in the recovery of anoxic regions following episodic high flow events. Furthermore, whilst a threshold salt wedge intrusion was a requirement for oxygen depletion, analysis of the results allowed us to quantify the effect of temperature in determining the overall severity and extent of hypoxia and anoxia. Climate warming scenarios highlighted that oxygen depletion is likely to be exacerbated through changes in flow regimes and warming temperatures; however, the increasing risk of hypoxia and anoxia can be mitigated through management of minimum flow allocations and targeted reductions in organic matter loading. A simple statistical model (R2 > 0.65) is suggested to relate riverine flow and temperature to the extent of estuary-wide anoxia.
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Bertani, I., I. Ferrari, and G. Rossetti. "Role of intra-community biotic interactions in structuring riverine zooplankton under low-flow, summer conditions." Journal of Plankton Research 34, no. 4 (January 18, 2012): 308–20. http://dx.doi.org/10.1093/plankt/fbr111.
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Hetland, Robert D., and W. Rockwell Geyer. "An Idealized Study of the Structure of Long, Partially Mixed Estuaries*." Journal of Physical Oceanography 34, no. 12 (December 1, 2004): 2677–91. http://dx.doi.org/10.1175/jpo2646.1.
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Abstract Classic models of estuarine circulation are reexamined using a three-dimensional, primitive equation numerical ocean model. The model is configured using an idealized estuary/shelf domain with rectangular cross section, constant vertical mixing, and steady riverine discharge. Tidal dispersion is neglected, so the analysis does apply to well-mixed estuaries and lagoons. Estuarine scales for the length of steady-state salt intrusion, vertical stratification, and estuarine exchange flow estimated from steady-state model results are found to have the same functional relationships to vertical mixing and riverine discharge as the classic analytic solutions. For example, for steady-state conditions, the stratification is found to be virtually independent of the strength of vertical mixing. The estuarine structure was controlled by the interior estuarine circulation, and not by limited exchange at the mouth. Thus, the numerical solutions were not “overmixed,” although the solutions showed a dependence on freshwater flux functionally similar to the overmixed solution. Estuarine adjustment time scales are also estimated from the simulations, and they are related to the steady-state estuarine scales. Two classes of nonsteady solutions are examined: the response to a step change in riverine discharge and estuarine response to changes in vertical mixing. Spring/neap tidal variations are examined by modulating the (spatially constant) vertical mixing with a fortnightly period. Unlike the steady solutions, there is a clear dependence of stratification on mixing rate in the time-dependent solutions. The simulations involving changes in riverine discharge show asymmetries between response to increasing and decreasing river flow that are attributed to quadratic bottom drag.
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Magner, J. A., and S. C. Alexander. "Geochemical and isotopic tracing of water in nested southern Minnesota corn-belt watersheds." Water Science and Technology 45, no. 9 (May 1, 2002): 37–42. http://dx.doi.org/10.2166/wst.2002.0199.
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Land-use changes over the last century in southern Minnesota have influenced riverine water chemistry. A nested watershed approach was used to examine hydrologic pathways of water movement in this now agriculturally intensive region. From field scale subsurface tile-drains of the Beauford ditch to the respective outlets of the Cobb River and Blue Earth River, more than 125 samples were collected for major dissolved ions and isotopes between March 1994 and June 1996 over a range of climatic conditions that included snowmelt and storm-flows. Results indicate that riverine water chemistry is dominated by subsurface tile-drained row crop agriculture. In the mid-1990s, regional ground water discharge into the Cobb and Blue Earth Rivers comprised less than 10% of the total flow based on ionic mixing calculations. Ammonia, present in manure or as anhydrous, is readily exchanged in the soil. This ion exchange releases increasing ratios of magnesium, sodium and strontium relative to calcium, the dominant cation. Soil thaw and snowmelt recharge influenced March–April tile-drain and ditch water isotopic values. Light δD values increased as spring infiltration-derived water was displaced from the soil zone by heavier summer precipitation. δ15N followed a similar but opposite pattern with relatively heavy March–April tile-drain and ditch values trending to lighter δ15N through the growing season. The future of southern Minnesota riverine water quality is closely linked to the management of the landscape. To improve the riverine environment, land owners and managers will need to address cropping systems, fertilization practices and drainage.
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Finlayson, C. Max, Peter A. Gell, and John Conallin. "<i>Corrigendum to</i>: Continuing the discussion about ecological futures for the lower Murray River (Australia) in the Anthropocene." Marine and Freshwater Research 73, no. 10 (May 3, 2021): 1245. http://dx.doi.org/10.1071/mf20344_co.
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The lower Murray River (Australia) has been subject to considerable change from human activities, including the conversion of a variable flow system to one with regulated water levels and the conversion of the estuary to a freshwater system. These conditions will face further pressures owing to reduced flows and higher sea levels associated with climate change. Policy decisions to retain present target conditions could be reconsidered to improve habitat conditions for wetlands, native fish and waterbirds. Contrary to many views, this would be permissible under the Ramsar Convention and, by increasing the diversity of conditions, may assist managers to retain functional systems. This paper encourages a new conversation across the broader community to develop pathways to prepare for emerging pressures on the riverine ecosystems, and move into anthropogenic futures for the Lower Murray.
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Hidayat, Jafron Wasiq, Maryono Maryono, and Rini Budhihastuti. "Quality of Plankton and Physic-chemical Factors to Support Fisheries and Community Care in Babon River, Semarang, Central Java, Indonesia." E3S Web of Conferences 317 (2021): 01090. http://dx.doi.org/10.1051/e3sconf/202131701090.
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The research was conducted by observing the plankton biota, especially in the interaction and relationship between riverine biota and environmental factors. Plankton enable to provide an indication of environmental changes by determining the diversity (H’) and evenness (e) indices. Plankton sampling was carried out at 4 stations with different environmental conditions. Plankton were sampled using filtering method and analysed based on their diversity and evenness. Besides, analysis of its saprobic is also carried out to determine the level of pollution. The results showed that the most common species of planktons were Thallasiosera sp and Nitzchia spp. Thallasiosera dominates stagnant waters (dams) and prospect to support the growth of fish larvae. Other species which contribute to feed the fish larvae were Closterium. Diversity Index (H') shows that the status of the environment stability is in moderate condition, driven by temperature and speed of flow of the water. It is suggested that vegetative conservation on riverside area could reduce the temperature and speed of water flow and so providing more suitable habitat for biota therein
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Gualtieri, Carlo, Ivo Martone, Naziano Pantoja Filizola Junior, and Marco Ianniruberto. "Bedform Morphology in the Area of the Confluence of the Negro and Solimões-Amazon Rivers, Brazil." Water 12, no. 6 (June 6, 2020): 1630. http://dx.doi.org/10.3390/w12061630.
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Confluences are common components of all riverine systems, characterized by converging flow streamlines and the mixing of separate flows. The fluid dynamics of confluences possesses a highly complex structure with several common types of flow features observed. A field study was recently conducted in the area of the confluence of the Negro and Solimões/Amazon Rivers, Brazil, collecting a series of Acoustic Doppler Current Profiler (ADCP) transects in different flow conditions. These data were used to investigate the morphology of the bedforms observed in that area. First, the bedforms were mostly classified as large and very large dunes according to Ashley et al. (1990), with an observed maximum wavelength and wave height of 350 and 12 m, respectively. Second, a comparison between low flow and relatively high flow conditions showed that wavelength and wave height increased as the river discharge increased in agreement with previous literature studies. Third, the lee side angle was consistently below 10°, with an average value of about 3.0°, without flow separation confirming past findings on low-angle dunes. Finally, a comparison between the bedform sizes and past literature studies on large rivers suggested that while several dunes were in equilibrium with the flow, several largest bedforms were found to be probably adapting to discharge changes in the river.
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Goldney, D., and L. Gilbert. "An Assessment of Stream Flow Modelling Combined with The Montana Method as a Basis for Developing Optimal Environmental Flows Below a Proposed Dam." Australian Mammalogy 20, no. 2 (1998): 303. http://dx.doi.org/10.1071/am98308.
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Little research has been carried out in Australia to determine the riparian and environmental flows needed to maintain riverine ecosystem integrity. Given the range of organisms present in the Australian freshwater biota, each with its own optimal requirements, it is probable that management flow conditions arrived at from species-specific studies, may not necessarily benefit all organisms. We also have inadequate understanding of how freshwater organisms interact with dynamic changes that occur in river systems (drought and flood), and the generally degraded nature of these streams. Hence formulating management outcomes in regard to flow conditions must be viewed as a particularly complex issue. In this paper a case history study is described for a tableland stream in the central west of New South Wales, where a major dam is being built on a first order stream. Comparisons are made with three other creek/river systems in the central tablelands and some implications for platypus conservation are identified.
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Strelnikova, Dariia, Gernot Paulus, Sabine Käfer, Karl-Heinrich Anders, Peter Mayr, Helmut Mader, Ulf Scherling, and Rudi Schneeberger. "Drone-Based Optical Measurements of Heterogeneous Surface Velocity Fields around Fish Passages at Hydropower Dams." Remote Sensing 12, no. 3 (January 25, 2020): 384. http://dx.doi.org/10.3390/rs12030384.
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In Austria, more than a half of all electricity is produced with the help of hydropower plants. To reduce their ecological impact, dams are being equipped with fish passages that support connectivity of habitats of riverine fish species, contributing to hydropower sustainability. The efficiency of fish passages is being constantly monitored and improved. Since the likelihood of fish passages to be discovered by fish depends, inter alia, on flow conditions near their entrances, these conditions have to be monitored as well. In this study, we employ large-scale particle image velocimetry (LSPIV) in seeded flow conditions to analyse images of the area near a fish passage entrance, captured with the help of a ready-to-fly consumer drone. We apply LSPIV to short image sequences and test different LSPIV interrogation area sizes and correlation methods. The study demonstrates that LSPIV based on ensemble correlation yields velocities that are in good agreement with the reference values regarding both magnitude and flow direction. Therefore, this non-intrusive methodology has a potential to be used for flow monitoring near fish passages on a regular basis, enabling timely reaction to undesired changes in flow conditions when possible.
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Bunya, S., J. C. Dietrich, J. J. Westerink, B. A. Ebersole, J. M. Smith, J. H. Atkinson, R. Jensen, et al. "A High-Resolution Coupled Riverine Flow, Tide, Wind, Wind Wave, and Storm Surge Model for Southern Louisiana and Mississippi. Part I: Model Development and Validation." Monthly Weather Review 138, no. 2 (February 1, 2010): 345–77. http://dx.doi.org/10.1175/2009mwr2906.1.
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Abstract A coupled system of wind, wind wave, and coastal circulation models has been implemented for southern Louisiana and Mississippi to simulate riverine flows, tides, wind waves, and hurricane storm surge in the region. The system combines the NOAA Hurricane Research Division Wind Analysis System (H*WIND) and the Interactive Objective Kinematic Analysis (IOKA) kinematic wind analyses, the Wave Model (WAM) offshore and Steady-State Irregular Wave (STWAVE) nearshore wind wave models, and the Advanced Circulation (ADCIRC) basin to channel-scale unstructured grid circulation model. The system emphasizes a high-resolution (down to 50 m) representation of the geometry, bathymetry, and topography; nonlinear coupling of all processes including wind wave radiation stress-induced set up; and objective specification of frictional parameters based on land-cover databases and commonly used parameters. Riverine flows and tides are validated for no storm conditions, while winds, wind waves, hydrographs, and high water marks are validated for Hurricanes Katrina and Rita.
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Balcombe, Stephen R., and Angela H. Arthington. "Temporal changes in fish abundance in response to hydrological variability in a dryland floodplain river." Marine and Freshwater Research 60, no. 2 (2009): 146. http://dx.doi.org/10.1071/mf08118.
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Riverine fish living in unpredictable flow environments tend to be ecological generalists with traits that allow them to persist under highly variable and often harsh conditions associated with hydrological variation. Cooper Creek, an Australian dryland river, is characterised by extreme flow variability, especially in the magnitude, timing and duration of channel flows and floods, which, if they occur, do so mainly in summer. The present study examined the influence of hydrological variability on fish assemblages and abundance in four waterholes in the Windorah reach of Cooper Creek over eight occasions between 2001 and 2004. Antecedent flows had marked influences on fish species richness and assemblage structure. Following high summer flows, all waterholes supported a rich and abundant fish fauna, whereas fewer species and lower numbers were recorded following periods of zero channel flow. Recruitment of three of the four most common and abundant species was enhanced when intermittent flows inundated backwater and floodplain habitats that provide a food-rich environment. Opportunistic responses to rising channel flows and occasional large floods in Cooper Creek help to explain the prominent ‘boom’ patterns of fish production in this arid-zone river, whereas low-level recruitment during periods of low or no flow maintains populations of some species through the ‘bust’.
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Tauro, Flavia, Andrea Petroselli, Maurizio Porfiri, Lorenzo Giandomenico, Guido Bernardi, Francesco Mele, Domenico Spina, and Salvatore Grimaldi. "A novel permanent gauge-cam station for surface-flow observations on the Tiber River." Geoscientific Instrumentation, Methods and Data Systems 5, no. 1 (June 22, 2016): 241–51. http://dx.doi.org/10.5194/gi-5-241-2016.
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Abstract. Flow monitoring of riverine environments is crucial for hydrology and hydraulic engineering practice. Besides few experimental implementations, flow gauging relies on local water level and surface-flow velocity measurements through ultrasonic meters and radars. In this paper, we describe a novel permanent gauge-cam station for large-scale and continuous observation of surface flows, based on remote acquisition and calibration of video data. Located on the Tiber River, in the center of Rome, Italy, the station captures 1 min videos every 10 min over an area oriented along the river cross section of up to 20.6 × 15.5 m2. In a feasibility study, we demonstrate that accurate surface-flow velocity estimations can be obtained by analyzing experimental images via particle tracking velocimetry (PTV). In medium illumination conditions (70–75 lux), PTV leads to velocity estimations in close agreement with radar records and is less affected by uneven lighting than large-scale particle image velocimetry. Future efforts will be devoted to the development of a comprehensive test bed infrastructure for investigating the potential of multiple optics-based approaches for surface hydrology.
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Herzog, Simon David, Per Persson, Kristina Kvashnina, and Emma Sofia Kritzberg. "Organic iron complexes enhance iron transport capacity along estuarine salinity gradients of Baltic estuaries." Biogeosciences 17, no. 2 (January 22, 2020): 331–44. http://dx.doi.org/10.5194/bg-17-331-2020.
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Abstract. Rivers discharge a notable amount of dissolved Fe (1.5×109 mol yr−1) to coastal waters but are still not considered important sources of bioavailable Fe to open marine waters. The reason is that the vast majority of particular and dissolved riverine Fe is considered to be lost to the sediment due to aggregation during estuarine mixing. Recently, however, several studies demonstrated relatively high stability of riverine Fe to salinity-induced aggregation, and it has been proposed that organically complexed Fe (Fe-OM) can “survive” the salinity gradient, while Fe (oxy)hydroxides are more prone to aggregation and selectively removed. In this study, we directly identified, by X-ray absorption spectroscopy, the occurrence of these two Fe phases across eight boreal rivers draining into the Baltic Sea and confirmed a significant but variable contribution of Fe-OM in relation to Fe (oxy)hydroxides among river mouths. We further found that Fe-OM was more prevalent at high flow conditions in spring than at low flow conditions during autumn and that Fe-OM was more dominant upstream in a catchment than at the river mouth. The stability of Fe to increasing salinity, as assessed by artificial mixing experiments, correlated well to the relative contribution of Fe-OM, confirming that organic complexes promote Fe transport capacity. This study suggests that boreal rivers may provide significant amounts of potentially bioavailable Fe beyond the estuary, due to organic matter complexes.
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Ioli, F., L. Pinto, D. Passoni, V. Nova, and M. Detert. "EVALUATION OF AIRBORNE IMAGE VELOCIMETRY APPROACHES USING LOW-COST UAVS IN RIVERINE ENVIRONMENTS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2020 (August 12, 2020): 597–604. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2020-597-2020.
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Abstract. Traditional flow velocity measurements in natural environments require contact with the fluid and are usually costly, time-consuming and, sometimes, even dangerous. Particle Image Velocimetry allows the flow velocity field to be remotely characterized from the shift of intensity patterns of sub-image areas in at least two video frames with a known time lag. Recently, Airborne Image Velocimetry has enabled the surface velocity field of large-scale water bodies to be determined by applying Particle Image Velocimetry on videos recorded by cameras mounted on unmanned aerial vehicles. This work presents a comparison of three Airborne Image Velocimetry approaches: BASESURV, Fudaa-LSPIV and RIVeR. For the evaluation, two nadiral videos were acquired with a low-cost quadcopter. The first was recorded under low flow and seeded conditions, the second during a flood event. According to the results obtained, BASESURV is an accurate and complete research oriented approach but it is time-consuming and neither a graphical interface nor documentation are yet provided. Fudaa-LSPIV is a well-developed software package, with a user-friendly graphical interface and good documentation. However it lacks some features and the source code is closed. RIVeR may be suitable for real time monitoring thanks to the rectification of velocity vectors only. Overall, all the codes are found to be effective in performing Airborne Image Velocimetry in riverine environments.
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Guan, Dawei, Jingang Liu, Yee-Meng Chiew, and Yingzheng Zhou. "Scour Evolution Downstream of Submerged Weirs in Clear Water Scour Conditions." Water 11, no. 9 (August 22, 2019): 1746. http://dx.doi.org/10.3390/w11091746.
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Although weirs or dikes in the riverine and coastal environments are frequently overtopped, few studies have hitherto examined the evolution of the scour process downstream of these structures under the submerged condition. This paper presents an experimental investigation on time evolution of the scour process downstream of submerged weirs with a uniform coarse sand. The clear-water scour experiments were carried out in a tilting recirculation flume. Different flow intensities and overtopping ratios (approach flow depth/weir height) were adopted in the experiments. Experimental observations show that the scour hole downstream of submerged weirs develops very fast in the initial stage, before progressing at a decreasing rate and eventually reaching the equilibrium stage. The results show that an increase of the overtopping ratio or flowrate can generate larger scour depth and volume downstream of the weir. Moreover, geometrical similarity of the scour hole that formed downstream of the weir was observed in the tests. Finally, empirical equations for predicting scour hole geometrical evolutions downstream of the submerged weirs were presented. The results of this study are useful in the development of numerical/analytical models capable of estimating the scour depth downstream of weirs in the river or coastal areas, for which the overtopping conditions are present.
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Nicholson, Geoff, Gregory P. Jenkins, John Sherwood, and Andy Longmore. "Physical environmental conditions, spawning and early-life stages of an estuarine fish: climate change implications for recruitment in intermittently open estuaries." Marine and Freshwater Research 59, no. 8 (2008): 735. http://dx.doi.org/10.1071/mf07197.
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Significant variation in the egg and larval survival and juvenile recruitment of estuarine fishes has been linked to fluctuating environmental conditions. This present study compared the distribution and abundance of black bream (Acanthopagrus butcheri) eggs and yolk-sac larvae between two microtidal estuaries of different flow regimes, where the riverine flow into the Glenelg estuary was around eight times the flow volume into the Hopkins estuary. Samples were collected monthly from September to November at sites along each estuary where vertical profiles of temperature, salinity and dissolved oxygen (DO) were measured, and vertically stratified sampling of black bream eggs and yolk-sac larvae was conducted using a Schindler sampler. Salt wedge formation was apparent in both estuaries, with significant de-oxygenation of deeper, saline waters. Eggs occurred in a wide range of DO levels but yolk-sac larvae were less common at the lowest levels. Most eggs and yolk-sac larvae were collected in salinities greater than 10. Results suggested that egg mortality was higher in the Hopkins than the Glenelg estuary, which may be associated with the hypoxic conditions characteristic of low-flow conditions. The results have significant implications in terms of climate change that is predicted to lead to warmer, drier conditions in south-eastern Australia, potentially increasing stratification and subsequent hypoxic zones.
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Stitz, Leigh, Larelle Fabbro, and Susan Kinnear. "Macroinvertebrate community succession under variable flow regimes in subtropical Australia." Marine and Freshwater Research 68, no. 6 (2017): 1153. http://dx.doi.org/10.1071/mf15341.
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Seasonal changes in hydrology are important factors influencing abiotic conditions and subsequently the biota. Although these effects have been studied in tropical catchments and in central arid Australia, subtropical ephemeral streams have largely been ignored. In the present study, three ephemeral streams in Central Queensland were monitored over 15 months. We hypothesised that macroinvertebrate abundance would increase gradually following the initial flow pulse and that abundance would increase until the pools began drying, with sensitive taxa only present during higher flow. In all, 69 families from 14 orders were collected in 128 samples. Significant relationships were not detected between low flow conditions and taxa richness (P>0.05). Principal component analysis showed that the macroinvertebrate communities did not change in response to the drying of pools. Significant differences were not observed between taxa richness, abundance nor tolerant taxa during varied periods of flow (P>0.05). Sensitive taxa were most abundant during high-flow periods with comparatively less abundance during no flow and drying periods. This study provides novel information on the flow-linked succession of macroinvertebrate communities in subtropical ephemeral streams and the results are important in informing the development of riverine indices and models used to manage subtropical environments.
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Vlaičević, Barbara, Vesna Gulin, Renata Matoničkin Kepčija, and Ivana Turković Čakalić. "Periphytic Ciliate Communities in Lake Ecosystem of Temperate Riverine Floodplain: Variability in Taxonomic and Functional Composition and Diversity with Seasons and Hydrological Changes." Water 14, no. 4 (February 12, 2022): 551. http://dx.doi.org/10.3390/w14040551.
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Periphytic ciliate communities of riverine floodplains have hardly been studied, although they play an important role in aquatic food webs and contribute to the overall ecosystem functioning. In this study we analyzed the taxonomic and functional composition and diversity of these communities across all seasons and hydrological phases. The study was conducted in a floodplain lake, a part of the large natural Danube floodplain, from February 2015 to September 2016. We found that higher temperature and hydrologically stable conditions during the lake isolation phase, when a high amount of suspended food is available, result in the highest ciliate abundances and dominance of relatively large suspension-feeding ciliates, mainly peritrichs, which could serve as good bioindicators for detecting disturbances in river-floodplain ecosystems. During the flow pulse phase, associated with lower temperatures, and during the phase of extreme floods, when the availability of suspended food was largely reduced, small surface-feeding ciliates prevailed in the periphyton. Further, while the total ciliate abundance was the lowest, the highest taxonomic and functional diversity was found, especially during an intermediate level of hydrological connectivity (flow pulse). Our results confirm the importance of different levels of hydrological connectivity for maintaining biodiversity in riverine floodplains and add to a growing awareness of the need to preserve the natural hydrological regimes of large rivers.
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Huang, Tao, Wilfred M. Wollheim, and Stephen H. Jones. "Removal of Fecal Indicator Bacteria by River Networks." Water 14, no. 4 (February 17, 2022): 617. http://dx.doi.org/10.3390/w14040617.
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Fecal contamination is a significant source of water quality impairment globally. Aquatic ecosystems can provide an important ecosystem service of fecal contamination removal. Understanding the processes that regulate the removal of fecal contamination among river networks across flow conditions is critical. We applied a river network model, the Framework for Aquatic Modeling in the Earth System (FrAMES-Ecoli), to quantify removal of fecal indicator bacteria by river networks across flow conditions during summers in a series of New England watersheds of different characteristics. FrAMES-Ecoli simulates sources, transport, and riverine removal of Escherichia coli (E. coli). Aquatic E. coli removal was simulated in both the water column and the hyporheic zone, and is a function of hydraulic conditions, flow exchange rates with the hyporheic zone, and die-off in each compartment. We found that, at the river network scale during summers, removal by river networks can be high (19–99%) with variability controlled by hydrologic conditions, watershed size, and distribution of sources in the watershed. Hydrology controls much of the variability, with 68–99% of network scale inputs removed under base flow conditions and 19–85% removed during storm events. Removal by the water column alone could not explain the observed pattern in E. coli, suggesting that processes such as hyporheic removal must be considered. These results suggest that river network removal of fecal indicator bacteria should be taken into consideration in managing fecal contamination at critical downstream receiving waters.
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Perona, P., and B. Crouzy. "Resilience of riverbed vegetation to uprooting by flow." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, no. 2211 (March 2018): 20170547. http://dx.doi.org/10.1098/rspa.2017.0547.
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Riverine ecosystem biodiversity is largely maintained by ecogeomorphic processes including vegetation renewal via uprooting and recovery times to flow disturbances. Plant roots thus heavily contribute to engineering resilience to perturbation of such ecosystems. We show that vegetation uprooting by flow occurs as a fatigue-like mechanism, which statistically requires a given exposure time to imposed riverbed flow erosion rates before the plant collapses. We formulate a physically based stochastic model for the actual plant rooting depth and the time-to-uprooting, which allows us to define plant resilience to uprooting for generic time-dependent flow erosion dynamics. This theory shows that plant resilience to uprooting depends on the time-to-uprooting and that root mechanical anchoring acts as a process memory stored within the plant–soil system. The model is validated against measured data of time-to-uprooting of Avena sativa seedlings with various root lengths under different flow conditions. This allows for assessing the natural variance of the uprooting-by-flow process and to compute the prediction entropy, which quantifies the relative importance of the deterministic and the random components affecting the process.
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Zhou, Zibo, Ian Cartwright, and Uwe Morgenstern. "Sources and mean transit times of stream water in an intermittent river system: the upper Wimmera River, southeast Australia." Hydrology and Earth System Sciences 26, no. 17 (September 9, 2022): 4497–513. http://dx.doi.org/10.5194/hess-26-4497-2022.
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Abstract. Determining the mean transit times (MTTs) and water sources in catchments at different flow conditions helps better understand river functioning, and manage river health and water resources. Despite being common in a range of environments, the MTTs and water sources in intermittent streams are much less well understood compared to perennial streams. Major ion geochemistry, stable isotopes, 14C, and 3H were used in this study to identify water sources and MTTs of the periodically intermittent upper Wimmera River from southeast Australia at different flow conditions, including zero-flow periods. The disconnected pool waters during the zero-flow period in the summer months of 2019 had 3H activities of 0.64 to 3.29 TU. These and the variations in total dissolved solids and stable isotopes imply that these pools contained a mixture of older groundwater and younger stream water impacted by evaporation. 3H activities during the high-flow period in July 2019 were 1.85 to 3.00 TU, yielding MTTs of up to 17 years. The 3H activities at moderate and low-flow conditions in September and November 2019 ranged from 2.26 to 2.88 TU, implying MTTs of 1.6 to 7.8 years. Regional groundwater near the Wimmera River had 3H activities of < 0.02 to 0.45 TU and 14C activities of 57 to 103 pMC, and was not recharged by the river at high flows. The Wimmera River and other intermittent streams in southeast Australia are sustained by younger catchment waters from relatively small near-river stores than comparable perennial streams, which have older deeper regional groundwater inputs. This results in these intermittent streams being more susceptible to short-term changes in climate and necessitates the protection of near-river corridors to maintain the health of the riverine systems.
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Reiman, Jeremy, and Y. Xu. "Diel Variability of pCO2 and CO2 Outgassing from the Lower Mississippi River: Implications for Riverine CO2 Outgassing Estimation." Water 11, no. 1 (December 27, 2018): 43. http://dx.doi.org/10.3390/w11010043.
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Carbon dioxide (CO2) outgassing from river surface waters is an important component of the global carbon cycle currently not well constrained. To test the hypothesis that riverine partial pressure of CO2 (pCO2) and CO2 outgassing rates differ between daylight and darkness, we conducted in-situ pCO2 and ambient water measurements over four 24-h periods in the spring and summer of 2018 in the Lower Mississippi River under varying flow regimes. We hypothesized that diel pCO2 variation will correlate inversely with solar radiation due to light-induced photosynthesis. Despite differing ambient conditions between seasons, we found a consistent diel cycle of riverine pCO2, with highest values before sunset and lowest values during peak daylight. Recorded pCO2 measurements varied by 206–607 µatm in spring and 344–377 µatm in summer, with significantly lower records during daylight in summer. CO2 outgassing was significantly lower during daylight in both seasons, with diel variation ranging between 1.5–4.4 mmol m−2 h−1 in spring and 1.9–2.1 mmol m−2 h−1 in summer. Daily outgassing rates calculated incorporating diel variation resulted in significantly greater rates (26.2 ± std. 12.7 mmol m−2 d−1) than calculations using a single daily pCO2 value. This study suggests a likely substantial underestimation of carbon outgassed from higher order rivers that make up a majority of the global river water surface. The findings highlight the need for high temporal resolution data and further research on diel CO2 outgassing in different climate regions to constrain uncertainties in riverine flux estimation.
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Pao, Chun-Hung, Jia-Lin Chen, Shih-Feng Su, Yu-Ching Huang, Wen-Hsin Huang, and Chien-Hung Kuo. "The Effect of Wave-Induced Current and Coastal Structure on Sediment Transport at the Zengwen River Mouth." Journal of Marine Science and Engineering 9, no. 3 (March 17, 2021): 333. http://dx.doi.org/10.3390/jmse9030333.
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The mechanisms that control estuarine sediment transport are complicated due to the interaction between riverine flows, tidal currents, waves, and wave-driven currents. In the past decade, severe seabed erosion and shoreline retreat along the sandy coast of western Taiwan have raised concerns regarding the sustainability of coastal structures. In this study, ADCPs (Acoustic Doppler Current Profiler) and turbidity meters were deployed at the mouth of the Zengwen river to obtain the time series and the spatial distribution of flow velocities and turbidity during the base flow and flood conditions. A nearshore circulation model, SHORECIRC, has been adapted into a hybrid finite-difference/finite-volume, TVD (Total Variation Diminishing)-type scheme and coupled with the wave-spectrum model Simulating Waves Nearshore (SWAN). Conventional finite-difference schemes often produce unphysical oscillations when modeling coastal processes with abrupt bathymetric changes at river mouths. In contrast, the TVD-type finite volume scheme allows for robust treatment of discontinuities through the shock-capturing mechanism. The model reproduces water levels, waves, currents observed at the mouth of the Zengwen River reasonably well. The simulated residual sediment transport patterns demonstrate that the transport process at the river mouth is dominated by the interaction of the bathymetry and wave-induced currents when the riverine discharge was kept in reservoirs. The offshore residual transport causes erosion at the northern part of the river mouth, and the onshore residual transport causes accretion in the ebb tidal shoals around the center of the river mouth. The simulated morphological evolution displays significant changes on shallower deltas. The location with significant sea bed changes is consistent with the spot in which severe erosion occurred in recent years. Further analysis of morphological evolution is also discussed to identify the role of coastal structures, for example, the extension of the newly constructed groins near the river mouth.
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Alessandrino, Luigi, and Micòl Mastrocicco. "Insight on the application of graphene to sandy soils to improve water holding capacity." Acque Sotterranee - Italian Journal of Groundwater 11, no. 4 (December 20, 2022): 35–41. http://dx.doi.org/10.7343/as-2022-588.
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In this study, the changes in relevant hydraulic parameters (namely hydraulic conductivity, total and effective porosity, specific retention, and longitudinal dispersivity) induced by the introduction of graphene in a calcareous sandy soil and a siliciclastic riverine soil were monitored and modelled via leaching column experiments. Constant pressure head tests were used to calculate the hydraulic conductivity of each column, while leaching experiments were run to estimate total porosity and specific retention, and for each treatment three replicates were done. Columns were then run under saturated conditions via a low flow peristaltic pump and monitored for chloride concentrations. CXTFIT 2.0 was employed to inversely model the column experiments and retrieve effective porosity and longitudinal dispersivity. Results highlighted small changes of hydraulic conductivity and porosity, induced by graphene addition for both soils. A marked increase of specific retention values was instead recorded in the amended columns respect to control ones. Chloride breakthrough curves modelling showed that graphene doubled dispersivity in the calcareous sandy soil compared to the control, while it halved dispersivity in the siliciclastic riverine soil with respect to the control. The results highlight that graphene induces positive shift in the capacity of sandy soil to retain porewater but at the same time it also alters solute transport parameters, like dispersivity, suggesting that further studies need to focus on using several exposure concentrations, durations and mode of exposure, and apply simulated field conditions or perform experiments in real field conditions, to understand the fate of unwanted compound in soils amended with graphene.
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Jin, Li, Paul G. Whitehead, Martyn N. Futter, and Zunli Lu. "Modelling the impacts of climate change on flow and nitrate in the River Thames: assessing potential adaptation strategies." Hydrology Research 43, no. 6 (January 27, 2012): 902–16. http://dx.doi.org/10.2166/nh.2011.080.
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The catchment of the River Thames, a principal river system in southern England, is densely populated and highly vulnerable to changes in climate, land use and population. In order to predict its vulnerability to climate change, the Integrated Catchments Model for Nitrogen (INCA-N) has been applied to the whole of the River Thames. The model was calibrated from 1999 to 2006, to simulate streamflow and nitrate (NO3-N) concentrations. Despite the highly variable land use and river flows within the catchment, INCA-N reproduced both the hydrological regime and NO3-N dynamics in the river. A sensitivity analysis was performed on measured flow and in-stream nitrogen transformation rates. It showed that simulated NO3-N concentrations were sensitive to denitrification rates and flow velocity. Measured parameter values were generally within the range of behavioural model simulations. Temperature and precipitation scenarios from the UK Climate Projections 2009 climate model outputs were used to project possible future flow and NO3-N concentration changes. Results showed generally drier hydrological conditions, increased river NO3-N concentration in winter and decreases in summer. An assessment of the planned new reservoir at Abingdon showed that, if managed appropriately, it may help offset the impact of climate change on riverine NO3-N concentrations and London's water supply.
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Brewer, Shannon K., and Charles F. Rabeni. "Interactions between natural-occurring landscape conditions and land use influencing the abundance of riverine smallmouth bass, Micropterus dolomieu." Canadian Journal of Fisheries and Aquatic Sciences 68, no. 11 (November 2011): 1922–33. http://dx.doi.org/10.1139/f2011-110.
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This study examined how interactions between natural landscape features and land use influenced the abundance of smallmouth bass, Micropterus dolomieu , in Missouri, USA, streams. Stream segments were placed into one of four groups based on natural-occurring watershed characteristics (soil texture and soil permeability) predicted to relate to smallmouth bass abundance. Within each group, stream segments were assigned forest (n = 3), pasture (n = 3), or urban (n = 3) designations based on the percentages of land use within each watershed. Analyses of variance indicated smallmouth bass densities differed between land use and natural conditions. Decision tree models indicated abundance was highest in forested stream segments and lowest in urban stream segments, regardless of group designation. Land use explained the most variation in decision tree models, but in-channel features of temperature, flow, and sediment also contributed significantly. These results are unique and indicate the importance of natural-occurring watershed conditions in defining the potential of populations and how finer-scale filters interact with land use to further alter population potential. Smallmouth bass has differing vulnerabilities to land-use attributes, and the better the natural watershed conditions are for population success, the more resilient these populations will be when land conversion occurs.
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Oliveira, Eduardo Negri de, Bastiaan Adriaan Knoppers, João Antônio Lorenzzetti, Paulo Ricardo Petter Medeiros, Maria Eulália Carneiro, and Weber Friederichs Landim de Souza. "A satellite view of riverine turbidity plumes on the NE-E Brazilian coastal zone." Brazilian Journal of Oceanography 60, no. 3 (September 2012): 283–98. http://dx.doi.org/10.1590/s1679-87592012000300002.
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Turbidity plumes of São Francisco, Caravelas, Doce, and Paraiba do Sul river systems, located along the NE/E Brazilian coast, are analyzed for their dispersal patterns of Total Suspended Solids (TSS) concentration using Landsat images and a logarithmic algorithm proposed by Tassan (1987) to convert satellite reflectance values to TSS. The TSS results obtained were compared to in situ collected TSS data. The analysis of the satellite image data set revealed that each river system exhibits a distinct turbidity plume dispersal pattern. The behavior, dimension and degree of turbidity of the São Francisco River plume have been greatly altered by the construction of a cascade of hydroelectric dam reservoirs in its hydrological basin. The plume has lost its typical unimodal seasonal pattern of material dispersion and its turbidity has decreased due to the regulation of river flow by the dams and TSS retainance by the reservoirs. In contrast, the Doce and Paraíba do Sul river plumes are still subject to seasonal pulsations and show more turbid conditions than the SF plume, as dams are less numerous, set in the middle river sections and the natural river flow has been maintained. The Caravelas Coastal System river plume is restricted to near shore shallow waters dominated by resuspension processes. During austral spring and summer when NE-E winds prevail, all plumes generally disperse southward. Short-term northward reversals may occur in winter with the passage of atmospheric cold fronts. The São Francisco and Doce river plumes tend to disperse obliquely to the coast and transport materials further offshore, while the Caravelas and Paraíba do Sul plumes tend to disperse mainly parallel to the coast, enhancing TSS retention nearshore.
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Mills, Peter B., and Duncan J. E. Hill. "Ancient Lake Maxima and Substrate-dependent Riverine Migration Have Defined the Range of the Mudpuppy (Necturus maculosus) in Southern Ontario Following the Wisconsinan Glaciation." Canadian Field-Naturalist 130, no. 2 (April 1, 2016): 158. http://dx.doi.org/10.22621/cfn.v130i2.1840.
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The Mudpuppy (Necturus maculosus) is an entirely aquatic salamander whose geographic range is thus defined by immigration routes in watersheds that permit feasible travel. Significant barriers, such as large waterfalls, effectively bar this species from further colonization upstream. We compared the contemporary distribution of Mudpuppies in southern Ontario with varying post-glacial ancient lake maxima and riverine outlet-flow conditions. Topography does not appear to be a range-limiting factor, but the type of river grade (waterfalls versus riffles) does. The distribution of modern records of this species in Ontario aligns closely with maxima from the Nipissing phase occurring 4000–5000 years ago, leading us to suggest that this is when Mudpuppies invaded and proliferated in the Great Lakes Basin.
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Jarvie, H. P., C. Neal, A. P. Rowland, M. Neal, P. N. Morris, J. R. Lead, A. J. Lawlor, et al. "Role of riverine colloids in macronutrient and metal partitioning and transport, along an upland–lowland land-use continuum, under low-flow conditions." Science of The Total Environment 434 (September 2012): 171–85. http://dx.doi.org/10.1016/j.scitotenv.2011.11.061.
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Ehrhardt, Sophie, Rohini Kumar, Jan H. Fleckenstein, Sabine Attinger, and Andreas Musolff. "Trajectories of nitrate input and output in three nested catchments along a land use gradient." Hydrology and Earth System Sciences 23, no. 9 (September 2, 2019): 3503–24. http://dx.doi.org/10.5194/hess-23-3503-2019.
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Abstract. Increased anthropogenic inputs of nitrogen (N) to the biosphere during the last few decades have resulted in increased groundwater and surface water concentrations of N (primarily as nitrate), posing a global problem. Although measures have been implemented to reduce N inputs, they have not always led to decreasing riverine nitrate concentrations and loads. This limited response to the measures can either be caused by the accumulation of organic N in the soils (biogeochemical legacy) – or by long travel times (TTs) of inorganic N to the streams (hydrological legacy). Here, we compare atmospheric and agricultural N inputs with long-term observations (1970–2016) of riverine nitrate concentrations and loads in a central German mesoscale catchment with three nested subcatchments of increasing agricultural land use. Based on a data-driven approach, we assess jointly the N budget and the effective TTs of N through the soil and groundwater compartments. In combination with long-term trajectories of the C–Q relationships, we evaluate the potential for and the characteristics of an N legacy. We show that in the 40-year-long observation period, the catchment (270 km2) with 60 % agricultural area received an N input of 53 437 t, while it exported 6592 t, indicating an overall retention of 88 %. Removal of N by denitrification could not sufficiently explain this imbalance. Log-normal travel time distributions (TTDs) that link the N input history to the riverine export differed seasonally, with modes spanning 7–22 years and the mean TTs being systematically shorter during the high-flow season as compared to low-flow conditions. Systematic shifts in the C–Q relationships were noticed over time that could be attributed to strong changes in N inputs resulting from agricultural intensification before 1989, the break-down of East German agriculture after 1989 and the seasonal differences in TTs. A chemostatic export regime of nitrate was only found after several years of stabilized N inputs. The changes in C–Q relationships suggest a dominance of the hydrological N legacy over the biogeochemical N fixation in the soils, as we expected to observe a stronger and even increasing dampening of the riverine N concentrations after sustained high N inputs. Our analyses reveal an imbalance between N input and output, long time-lags and a lack of significant denitrification in the catchment. All these suggest that catchment management needs to address both a longer-term reduction of N inputs and shorter-term mitigation of today's high N loads. The latter may be covered by interventions triggering denitrification, such as hedgerows around agricultural fields, riparian buffers zones or constructed wetlands. Further joint analyses of N budgets and TTs covering a higher variety of catchments will provide a deeper insight into N trajectories and their controlling parameters.
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Huang, Wei, Yufang Ni, Maggie Creed, and Sihan Yu. "Experimental Analysis of 3D Flow Structures around a Floating Dike." Water 15, no. 4 (February 10, 2023): 703. http://dx.doi.org/10.3390/w15040703.
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Floating dikes have several advantages over spur dikes including less influence on riverine sediment transport, bed topography, and ecosystems, and a good adaptability to fluvial conditions. Despite these advantages, floating dikes have not been used in many river regulation schemes due to the limited understanding of the 3D flow structures around floating dikes. In this study, a series of experiments were conducted to investigate the 3D flow structures around floating dikes. Results show that, after installing a floating dike on one side of a flume, the surface water flow is deflected to the opposite side of the flume, and a backflow develops around the outer and downstream side of the dike, where both the vertical turbulent intensity and the absolute magnitude of the Reynolds stress are relatively large. Due to the blocking effect of the dike, the cross-sectional area decreases, causing an increase in velocities below and alongside the dike, as well as a decrease in velocities upstream of the dike. Increasing the submerged depth or length of the dike results in an increase in flow velocity adjacent to the dike, as well as an increase in the vertical or lateral scale of the backflow. On the contrary, increasing the dike thickness leads to a weakening or disappearance of the backflow, along with a decrease in the acceleration rate of flow adjacent to the dike.
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Sharma, Urvashi. "Effective framework for Environmental-flows estimation for data deficient Indian rivers." Journal of Applied and Natural Science 11, no. 2 (June 10, 2019): 545–55. http://dx.doi.org/10.31018/jans.v11i2.2116.
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Data deficiency is a major problem in recommending appropriate environmental flows (e-flows) requirements for rivers in many parts of the world. Several studies have been done using a variety of e-flows assessment methodologies. Large dams and hydropower projects are major manipulators of the flow regimes resulting in degraded ecosystems ubiquitously. In India attempts have been made to develop e-flows requirements of rivers to maintain a good riverine ecosystem. Most of the studies are based on hydrological methods, which do not take all the variables affecting flow-regimes into consideration. This paper highlights the problems in assessment of e-flows and their on-ground implications in India. In this study, probable solutions to these problems are suggested a conceptual framework for data deficient areas is proposed. This framework is based upon extensive baseline surveys of fluvial morphology, ecology and of indigenous population. Framework has six steps namely: monitoring the baseline conditions, setting up objectives, hydrological analysis, ecological analysis, climatic anomalies incorporation and recommendations. Finally, e-flows recommendations are made based on hydrological studies, habitat suitability curves and area of inland water body which should be maintained in the river basin. All these recommendations are compared and suitable e-flows recommendations are made based on studied variables. The review also suggests for bottom-up approach for e-flows assessment i.e. e-flows assessment and application should be done on small tributaries of rivers in initial phase of projects and those methods which deliver satisfactory results should only be applied to larger rivers.
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Lin, Li, Weide Deng, Xiaoxia Huang, Yang Liu, Liangliang Huang, and Bin Kang. "How fish traits and functional diversity respond to environmental changes and species invasion in the largest river in Southeastern China." PeerJ 9 (July 23, 2021): e11824. http://dx.doi.org/10.7717/peerj.11824.
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Background Freshwater fish populations are facing multiple stressors, including climate change, species invasion, and anthropogenic interference. Temporal studies of fish functional diversity and community assembly rules based on trait-environment relationships provide insights into fish community structure in riverine ecosystems. Methods Fish samples were collected in 2015 in the Min River, the largest freshwater riverine system in Southeastern China. Fish functional diversity was compared with the background investigation in 1979. Changes in functional richness, functional evenness, functional divergence, and functional beta diversity were analyzed. Relationships between functional diversity and environmental factors were modeled by random forest regression. Correlations between fish functional traits and environmental factors were detected by fourth-corner combined with RLQ analysis. Results Functional richness was significantly reduced in 2015 compared with 1979. Functional beta diversity in 2015 was significantly higher than that in 1979, with functional nestedness being the driving component. Reduction of functional richness and domination of functional nestedness is associated with species loss. Trait convergence was the dominant mechanism driving the temporal changes of functional diversity. Precipitation, temperature, species invasion, and human population were the most significant factors driving fish functional diversity. Higher precipitation, higher temperature, and presence of invasive species were significantly associated with higher swimming factor and higher relative eye diameter, while the opposite environmental conditions were significantly associated with higher pectoral fin length and eurytopic water flow preference. Conclusions Environmental filtering is the dominant temporal assembly mechanism shaping fish community structure. This work contributes to the understanding of temporal freshwater fish community assembly and the associations between fish functional structure and local environmental conditions, which will be informative for future freshwater fish conservation.
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Nielsen, D. L., M. A. Brock, G. N. Rees, and D. S. Baldwin. "Effects of increasing salinity on freshwater ecosystems in Australia." Australian Journal of Botany 51, no. 6 (2003): 655. http://dx.doi.org/10.1071/bt02115.
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Salt is a natural component of the Australian landscape to which a number of biota inhabiting rivers and wetlands are adapted. Under natural flow conditions periods of low flow have resulted in the concentration of salts in wetlands and riverine pools. The organisms of these systems survive these salinities by tolerance or avoidance. Freshwater ecosystems in Australia are now becoming increasingly threatened by salinity because of rising saline groundwater and modification of the water regime reducing the frequency of high-flow (flushing) events, resulting in an accumulation of salt. Available data suggest that aquatic biota will be adversely affected as salinity exceeds 1000 mg L–1 (1500 EC) but there is limited information on how increasing salinity will affect the various life stages of the biota. Salinisation can lead to changes in the physical environment that will affect ecosystem processes. However, we know little about how salinity interacts with the way nutrients and carbon are processed within an ecosystem. This paper updates the knowledge base on how salinity affects the physical and biotic components of aquatic ecosystems and explores the needs for information on how structure and function of aquatic ecosystems change with increasing salinity.
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Boulton, A. J., and P. J. Hancock. "Rivers as groundwater-dependent ecosystems: a review of degrees of dependency, riverine processes and management implications." Australian Journal of Botany 54, no. 2 (2006): 133. http://dx.doi.org/10.1071/bt05074.
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Many rivers are classified as groundwater-dependent ecosystems (GDEs), owing to the contribution of groundwater to their base flow. However, there has been little explicit recognition of the way groundwater influences riverine biota or processes, how degrees of ecological dependency may vary, and the management implications of this dependency. The permeable beds and banks of these GDEs where surface water and groundwater exchange are termed ‘hyporheic zones’. They are often inhabited by invertebrates, with varying reliance on groundwater, although the ecological roles of these invertebrates are little known. Upwelling hyporheic water can promote surface primary productivity, influence sediment microbial activity, and affect organic matter decomposition. In many intermittent streams, variable groundwater inputs alter the duration of flow or water permanence, and the duration and timing of these largely govern the biota and rates of many ecosystem processes (e.g. leaf decomposition). Not only is the physical presence of water important, thermal and chemical conditions arising from groundwater inputs also have direct and indirect effects on riverine biota and rates or types of in-stream processes. Differing degrees of dependency of rivers on groundwater mediate all these influences, and may change over time and in response to human activities. Alteration of groundwater inputs through extraction from riparian wells or changes in local water table have an impact on these GDEs, and some current management plans aim to restrict groundwater extraction from near permeable river channels. However, these are often ‘blanket’ restrictions and the mechanisms of GDE dependency or timing of groundwater requirements are poorly understood, hampering refinement of this management approach. More effective management of these GDEs into the future can result only from a better understanding of the mechanisms of the dependency, how these vary among river types and what in-stream changes might be predicted from alteration of groundwater inputs.
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Zelnik, Igor, and Tjaša Muc. "Relationship between Environmental Conditions and Structure of Macroinvertebrate Community in a Hydromorphologically Altered Pre-Alpine River." Water 12, no. 11 (October 24, 2020): 2987. http://dx.doi.org/10.3390/w12112987.
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Hydromorphological alterations influence a wide range of environmental conditions as well as riparian vegetation and the structure of the macroinvertebrate community. We studied relationships between the structure and diversity of the macroinvertebrate community and hydromorphological and other environmental conditions in the river Gradaščica (central Slovenia). The Gradaščica river is a pre-Alpine torrential river that has been morphologically altered by humans. A selection of abiotic factors was measured, the ecomorphological status of the river was assessed, vegetation in the riparian zone was surveyed and benthic macroinvertebrates were sampled. Correlations between diversity and the structure of the macroinvertebrate community, environmental parameters and occurrence of invasive alien plant species in the riparian zone were identified. The significance of the influence of environmental parameters on the structure of the macroinvertebrate community was examined. We found that hydromorphological alterations in the river have had a significant influence on the diversity and composition of the macroinvertebrate community because of changes of flow velocity and the spread of invasive alien plant species that has followed those changes. Factors that also significantly influence the composition of macroinvertebrate community are distance from the source and conductivity. Our findings suggest minimization of further human hydromorphological changes of watercourses could prevent the loss of biodiversity of riverine ecosystems.
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Massmann, Carolina. "Reproducing different types of changes in hydrological indicators with rainfall-runoff models." Hydrology Research 51, no. 2 (March 30, 2020): 238–56. http://dx.doi.org/10.2166/nh.2020.073.
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Abstract Hydrological indicators support analyses about the impact of climate and anthropogenic changes on riverine ecosystems. As these studies often rely on hydrological models for estimating the future value of the indicators, it is important to investigate how well, and under which conditions, we can replicate changes in the indicators. This study looks at these questions by investigating the performance that can be achieved depending on the objective function for calibrating the model, the direction of the change in the indicator, the magnitude of this change and the properties of the catchments. The results indicate that, in general, indicators describing the magnitude of discharge (monthly and annual) can be adequately estimated with hydrological models, but that there are difficulties when estimating the characteristics of flow pulses, flow reversals and timing variables. For some of these indicators, it is not even possible to correctly estimate the direction of large changes. The analysis showed further that these problems cannot be resolved by adjusting the calibrated parameters, but that the model structure is unsuitable for modelling these indicators.
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Butler, Robert W. H. "Tectonic evolution of the Himalayan syntaxes: the view from Nanga Parbat." Geological Society, London, Special Publications 483, no. 1 (August 30, 2018): 215–54. http://dx.doi.org/10.1144/sp483.5.
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AbstractCurrent tectonic understanding of the Nanga Parbat–Haramosh massif (NPHM) is reviewed, developing new models for the structure and deformation of the Indian continental crust, its thermorheological evolution, and its relationship to surface processes. Comparisons are drawn with the Namche Barwa–Gyala Peri massif (NBGPM) that cores an equivalent syntaxis at the NE termination of the Himalayan arc. Both massifs show exceptionally rapid active denudation and riverine downcutting, identified from very young cooling ages measured from various thermochronometers. They also record relicts of high-pressure metamorphic conditions that chart early tectonic burial. Initial exhumation was probably exclusively by tectonic processes but the young, and continuing emergence of these massifs reflects combined tectonic and surface processes. The feedback mechanisms implicit in aneurysm models may have been overemphasized, especially the role of synkinematic granites as agents of rheological softening and strain localization. Patterns of distributed ductile deformation exhumed within the NPHM are consistent with models of orogen-wide gravitation flow, with the syntaxes forming the lateral edges to the flow beneath the Himalayan arc.
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Pastor, A. V., F. Ludwig, H. Biemans, H. Hoff, and P. Kabat. "Accounting for environmental flow requirements in global water assessments." Hydrology and Earth System Sciences 18, no. 12 (December 11, 2014): 5041–59. http://dx.doi.org/10.5194/hess-18-5041-2014.
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Abstract. As the water requirement for food production and other human needs grows, quantification of environmental flow requirements (EFRs) is necessary to assess the amount of water needed to sustain freshwater ecosystems. EFRs are the result of the quantification of water necessary to sustain the riverine ecosystem, which is calculated from the mean of an environmental flow (EF) method. In this study, five EF methods for calculating EFRs were compared with 11 case studies of locally assessed EFRs. We used three existing methods (Smakhtin, Tennant, and Tessmann) and two newly developed methods (the variable monthly flow method (VMF) and the Q90_Q50 method). All methods were compared globally and validated at local scales while mimicking the natural flow regime. The VMF and the Tessmann methods use algorithms to classify the flow regime into high, intermediate, and low-flow months and they take into account intra-annual variability by allocating EFRs with a percentage of mean monthly flow (MMF). The Q90_Q50 method allocates annual flow quantiles (Q90 and Q50) depending on the flow season. The results showed that, on average, 37% of annual discharge was required to sustain environmental flow requirement. More water is needed for environmental flows during low-flow periods (46–71% of average low-flows) compared to high-flow periods (17–45% of average high-flows). Environmental flow requirements estimates from the Tennant, Q90_Q50, and Smakhtin methods were higher than the locally calculated EFRs for river systems with relatively stable flows and were lower than the locally calculated EFRs for rivers with variable flows. The VMF and Tessmann methods showed the highest correlation with the locally calculated EFRs (R2=0.91). The main difference between the Tessmann and VMF methods is that the Tessmann method allocates all water to EFRs in low-flow periods while the VMF method allocates 60% of the flow in low-flow periods. Thus, other water sectors such as irrigation can withdraw up to 40% of the flow during the low-flow season and freshwater ecosystems can still be kept in reasonable ecological condition. The global applicability of the five methods was tested using the global vegetation and the Lund-Potsdam-Jena managed land (LPJmL) hydrological model. The calculated global annual EFRs for fair ecological conditions represent between 25 and 46% of mean annual flow (MAF). Variable flow regimes, such as the Nile, have lower EFRs (ranging from 12 to 48% of MAF) than stable tropical regimes such as the Amazon (which has EFRs ranging from 30 to 67% of MAF).
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Lin, Ji-Yuan, Jen-Chih Chao, and Yung-Ming Hsu. "Risk Assessment of Riverine Terraces: The Case of the Chenyulan River Watershed in Nantou County, Taiwan." Applied Sciences 12, no. 3 (January 27, 2022): 1375. http://dx.doi.org/10.3390/app12031375.
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The purpose of this study is to establish a method of hazard assessment for the river terraces along the Chenyulan River and use 40 of them as protected objects. Using a geographic information system, the researchers extracted nine parameters for such terraces. These are length to attack shore, distance away from fault, distance from river channel, number of creeks and streams with possibility of debris flows, height above stream level, average slope degree, geology, number of erosion ditches, and distance from landslide area behind. Next, the weightings identified by analytic hierarchy process analysis were used as the basis for grading the various factors affecting river terraces. Hazard assessment for the river terraces then proceeded via totaling of the potential trends of the various factors and the protected objects, as well as comparison of historical disaster conditions and satellite images. The results showed that there were 8 high-risk river terraces, 14 medium–high-risk river terraces, 14 medium–low-risk river terraces and 4 low-risk river terraces. The evaluation of the current conditions of the settlement environment through parameter weighting has a certain accuracy and reference value in reducing the disaster impact of the riverine terrace settlement.
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Nugroho, Adam Rus. "Application of a hydrological method for determining monthly environmental flow in Code River, Indonesia." IOP Conference Series: Earth and Environmental Science 933, no. 1 (November 1, 2021): 012015. http://dx.doi.org/10.1088/1755-1315/933/1/012015.
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Abstract The declining groundwater in Yogyakarta could potentially affect the Code River baseflow, thus lowering the river streamflow. Consequently, the riverine ecosystem would suffer from a low quantity of streamflow. The quantity standard of streamflow can be determined by calculating the environmental flow. In this study, the environmental flow requirement (EFR) for the Code River is determined by applying an enhanced version of the most-used hydrological method, namely the Modified Tennant Method based on Multilevel Habitat Conditions III (MTMMHC-III). The EFR in the Code River could be calculated successfully by the MTMMHC-III with a satisfactory temporal variability. The EFRs are the lowest during July to October in the normal years, July to September in the wet years, and July to December in the dry years. The EFRs are highest during January to April in the normal and dry years and January to May in the wet years. However, the EFR might become too low in the dry years, especially from the beginning of the dry season (May) until the early wet season (December), with only 4-11% of the average annual flow. Ultimately, the MTMMHC-III method is a better hydrological method than the original Tennant Method and Q95 method.