bluuebunny/crossref_metadata_2025_split huggingface dataset:
A scenario‐based holistic approach to environmental flow assessments for rivers
Authors: King Jackie , Brown Cate , Sabet Hossein 
Published: September 2003

AbstractAn Erratum has been published for this article in River Research and Applications 21(5) 2005, 509.
Sustainable use of river ecosystems requires that they be managed holistically. This paper describes an holistic methodology, DRIFT (Downstream Response to Imposed Flow Transformation), for advising on environmental flows for rivers targetted for water‐management activities. DRIFT's basic philosophy is that all major abiotic and biotic components constitute the ecosystem to be managed; and within that, the full spectrum of flows, and their temporal and spatial variability, constitute the flows to be managed. The methodology employs experienced scientists from the following biophysical disciplines: hydrology, hydraulics, fluvial geomorphology, sedimentology, chemistry, botany and zoology. Where there are subsistence users of the river, the following socio‐economic disciplines are also employed: sociology, anthropology, water supply, public health, livestock health and resource economics.DRIFT is a structured process for combining data and knowledge from all the disciplines to produce flow‐related scenarios for water managers to consider. It consists of four modules. In the first, or biophysical module, the river ecosystem is described and predictive capacity developed on how it would change with flow changes. In the second, or socio‐economic module, links are described between riparian people who are subsistence users of river resources, the resources they use, and their health. The objective is to develop predictive capacity of how river changes would impact their lives. In the third module, scenarios are built of potential future flows and the impacts of these on the river and the riparian people. The fourth, or economic module, lists compensation and mitigation costs.DRIFT should run in parallel with two other exercises which are external to it: a macro‐economic assessment of the wider implications of each scenario, and a Public Participation Process whereby people other than subsistence users can indicate the level of acceptability of each scenario.DRIFT has been developed in a semi‐arid, developing region, where water‐supply problems are pressing, and uncertainties about river‐linked ecological and social processes high. The use of DRIFT in this context is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Interannual variation of fish assemblage structure in a Mediterranean river: implications of streamflow on the dominance of native or exotic species
Authors: Bernardo João M. , Ilhéu Maria , Matono Paula , Costa Ana M. 
Published: September 2003

AbstractStreams in mediterranean‐type climate regions are shaped by predictable seasonal events of flooding and drying over an annual cycle, but also present a strong interannual flow variation.The Guadiana River is one of the most important rivers in the Iberian Peninsula. The fish fauna presents 11 native freshwater species, including eight with high conservation status. Several exotic species are present, the most important being the American centrarchids pumpkinseed fish and largemouth bass. As a typical mediterranean‐type river, the Guadiana has an irregular hydrological regime with severe drought periods and floods; the interannual variation of discharge presents a ratio of c. 100 to 1.From 1980 to 1995 several dry years were observed, culminating in the drought of 19910/92–19947/95. Analysing the variation of the fish assemblage structure during this period, exotic species (mostly pumpkinseed) progressively increased, strongly dominating in 1995. Indigenous populations dramatically decreased and a previously common endemic cyprinid (Anaecypris hispanica Steindachner) became endangered and one of the most threatened fishes of Europe. However, the following years presented above‐average flows with several flood events and an inverse process occurred, with native species increasing their contribution in a short period.The importance of floods as a disturbance factor in the control of lentic or slow flowing water exotics is discussed. Native species apparently possess adaptive responses to high flows which exotics lack. This hypothesis is consistent with probability‐of‐use curves and preflood–postflood surveys. Results emphasize the importance of floods in the environmental flows of mediterranean‐type rivers. In the absence of flooding disturbance, exotic fish populations predictably grow, increasing the pressure on native species; abiotic disturbance may supersede deterministic outcomes of predation or competition and influence community structure by reducing populations of the exotic species. Copyright © 2003 John Wiley & Sons, Ltd.
Do juvenile Atlantic salmon parr track local changes in water velocity?
Authors: Kemp P. S. , Gilvear D. J. , Armstrong J. D. 
Published: September 2003

AbstractWhen given a choice of two flows and constant food availability, salmon parr should choose the lower flow if they are to optimize their net energy gain . In a two‐choice test carried out in a recirculating flume, there was no significant selection for ranges of naturally occurring high (mean mid‐column velocities of 19.5–25.2 cm s−1) or low (7.2–10.0 cm s−1) summer flows. To test whether this result might indicate that only a proportion of the population chose optimal flows, the positions of the flows were reversed. All fish that initially chose low flow remained site‐attached when the flows were reversed. A significant proportion of the fish that initially chose high flow moved when the flows were reversed. Hence, there is no evidence that salmon can integrate energy costs and gains to optimize their feeding positions. However, the behaviour of some individual fish was consistent with a ‘rule of thumb’ of following high flows, which may improve foraging efficiency in natural streams above random in the long but not short term. The findings show that only a fraction of the parr in a population redistribute themselves in response to changes in discharge and therefore a fundamental assumption of some instream flow models is questioned. © Crown Copyright 2003. Reproduced with the permission of her majesty's stationery office. Published by John Wiley & Sons, Ltd.
Environmental flow requirements of fish in Lesotho rivers using the DRIFT methodology
Authors: Arthington Angela H. , Rall Johan L. , Kennard Mark J. , Pusey Bradley J. 
Published: September 2003

AbstractDRIFT (Downstream Response to Imposed Flow Transformations) is a scenario‐based environmental flow assessment methodology applied during impact studies associated with the Lesotho Highlands Water Project, Southern Africa. DRIFT offers a structured process for predicting the biophysical, social and economic consequences of altering a river's flow regime. The fish component of DRIFT provides a ten‐step protocol designed to make such predictions using field data on a river's fish fauna linked to information on flow‐related aspects of fish biology drawn from the literature and the knowledge base and professional experience of fish ecologists. A worked example of the methodology is presented based on a study site downstream from Katse Dam on the Malibamatso River, Lesotho, where the ecological consequences of four flow scenarios were evaluated. DRIFT and its fish component have emerged from studies in a semi‐arid, developing region where unpredictable hydrological regimes and data scarcity constrain the prediction of ecological responses to flow regulation. Faced with similar information constraints, scientific uncertainty and limited windows of opportunity to guide water management, other countries have employed scientific panels to recommend environmental flows. DRIFT and its fish component compare favourably with recommended best practice for Australian scientific panel assessments of the flow requirements of river ecosystems. The risks associated with use of scientific panel approaches are discussed and minimum data sets and standards are recommended for the conduct of a DRIFT fish assessment. DRIFT and related frameworks represent the second level in a three‐tiered hierarchy of environmental flow methods. They can provide environmental flow recommendations of far greater scientific resolution than hydrological methods by integrating many types of information on the responses of riverine biota to flow modifications. However, DRIFT should only be applied within an adaptive management framework where there is a genuine commitment to the generation and use of new knowledge derived from monitoring and research. Copyright © 2003 John Wiley & Sons, Ltd.
A population dynamics model and habitat simulation as a tool to predict brown trout demography in natural and bypassed stream reaches
Authors: Capra H. , Sabaton C. , Gouraud V. , Souchon Y. , Lim P. 
Published: September 2003

AbstractThe real impact on downstream fish populations of a change in management of a hydropower installation, in particular, the impact of an increase in instream minimum flow, can be difficult to assess. Other factors, in addition to the simple habitat limitations in low‐flow periods, can influence the evolution of a fish population over time. It has often observed in French streams that the 0+ individuals appear limited by strong discharge in the first months after their emergence (March to May). A dynamic model of a trout populations (MODYPOP) has been applied to the river Roizonne in the French Alps, upstream and downstream of a hydropower station, in order to estimate the effect of different discharge time series on trout population dynamics. Trout populations were monitored by means of annual inventories at two study sites, one with minimum flow and the other with natural flow. At each site, available habitat was described and simulated as it changed with discharge, according to the ‘microhabitat’ method (EVHA, derived from PHABSIM). Habitat time series were built on the basis of discharge time series. MODYPOP simulations, integrating habitat and discharge time series, were compared with observed fish numbers. Results indicated that fluctuations in discharge during the post‐emergence period played a major role in the dynamics of the total population. Predictions were significantly improved when the impact of strong discharge on emerging fry was integrated in the model. Copyright © 2003 John Wiley & Sons, Ltd.
Plant community responses to wetting and drying in a large arid floodplain
Authors: Capon Samantha J. 
Published: September 2003

AbstractThe flow regimes of large arid river catchments are amongst the most variable in the world. Plant communities which inhabit arid floodplains typically exhibit high spatial heterogeneity and are temporally dynamic in response to changing flow conditions. It has been suggested that arid floodplain ecosystems, adapted as they are to variability, will be relatively resilient to anthropogenic alterations to flow. This paper argues that floodplain plant communities in arid catchments, as in temperate and tropical regions, are primarily structured by flow regimes despite their inherent unpredictability. Consequently, changes to flood pulses through water extraction can be expected to result in changes in vegetation composition and structure which in turn may have a dramatic effect on wider ecosystem functioning. Results are presented from an ongoing study of the Cooper Creek floodplain in central Australia which illustrate the relationships between plant community dynamics and variable flood pulses. These results indicate that alterations to flow may result in a shift in community structure and an eventual loss of biodiversity. It is essential, therefore, that water resource managers in arid regions consider the requirements of floodplain plant communities when allocating environmental flows. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of flow dynamics and sediment movement on microbial activity in a lowland river
Authors: Fischer Helmut , Sukhodolov Alexander , Wilczek Sabine , Engelhardt Christof 
Published: September 2003

AbstractFluvial systems transport sediments in suspension and in bed‐load together with bacteria adhering to the transported particles. Activity of these bacteria is assumed to be critical for processes of self‐purification of river waters. Here we present the results of multidisciplinary research designed to provide insight into how turbulent flow and movable sediments affect bacterial activity. Bacterial density and activity were investigated at 0–2, 9–11 and 18–20 cm sediment depth at three profiles longitudinally spaced along a sandy dune in the lowland River Spree in Germany. Dynamics of riverbed relief were examined via high‐resolution spatial and temporal echo‐sounding surveys. Three‐dimensional turbulent flow structure was measured at three vertical profiles, the locations of which coincided with the positions of bacterial samples. Bacterial activity was high in the upper 10 cm layer of sand which was moving relatively fast in the form of comparatively small sand waves, and significantly lower in the slow‐moving deeper layer associated with larger, slowly migrating dunes. The thickness of the upper layer tended to decrease towards the sand dune crests. A transition zone between high and low activity was found in the 9–11 cm sediment layer. The local depth of this transition zone also matched the local values of displacement heights computed from turbulent stresses profiles. We demonstrate that information on characteristic scales of sand wave motion may define regions of high bacterial activity for rivers with non‐cohesive, sandy sediment deposits. Copyright © 2003 John Wiley & Sons, Ltd.
Incorporating flow variability into environmental flow regimes using the flow events method
Authors: Stewardson Michael J. , Gippel Christopher J. 
Published: September 2003

AbstractIncreased understanding of the ecological importance of temporal environmental variation has led to a concern that many regulated rivers lack the natural variations in flow required to maintain pre‐regulation communities. Many of the existing environmental flow methods fail to adequately address this concern. This paper presents a new approach to characterizing flow variations for environmental flow studies using knowledge of the influence of flow events on biological and geomorphic processes. This approach has the advantage that ecological benefits of the environmental flow are clearly articulated, available knowledge is included in the development of flow recommendations and the method accounts for the natural dynamism in flow‐related ecosystem processes by using the natural flow regime as a template for the environmental flow regime. The Flow Events Method is demonstrated in an application to the Snowy River in southeast Australia. Copyright © 2003 John Wiley & Sons, Ltd.
The behavioural response of juvenile Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) to experimental hydropeaking on a Newfoundland (Canada) river
Authors: Scruton D. A. , Ollerhead L. M. N. , Clarke K. D. , Pennell C. , Alfredsen K. , Harby A. , Kelley D. 
Published: September 2003

AbstractDeregulation of the electric power market globally will lead to increased requirement for electricity on demand resulting in more emphasis on ‘hydropeaking’ generation. A research study was conducted on the regulated West Salmon River, Newfoundland, Canada, to examine habitat selection and movement of juvenile Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) in response to flow changes related to ‘experimental’ peaking flow power generation. Fish were surgically implanted with microscale radio transmitters, released into an experimental study, and discharge was experimentally manipulated simulating two scenarios: (i) water storage during the day and generation at night, with a 2 hour transition; and (ii) night‐time storage with generation during the day. Experiments were repeated in the summer and fall. Fish were tracked throughout the diurnal cycle of each manipulation and precisely positioned in two‐dimensional space. Atlantic salmon exhibited two distinct patterns to movement: fish that showed high site fidelity and those that moved considerably during trials. Both salmon and trout were more active during fall hydropeaking experiments. Fish generally did not move long distances and moved more in a longitudinal fashion than laterally. Salmon moved greater distances, on average, than trout under all experimental conditions and during both seasons but these differences were not statistically significant. Brook trout moved more in relation to dynamic events (up‐ and down‐ramping) than at steady state flows. Trout also moved more at night during these dynamic changes and under low flow conditions. These results will assist producers of hydroelectricity to reduce the impacts of hydropeaking operations on fish and fish habitat. Copyright © 2003 John Wiley & Sons, Ltd.
Hydraulic constraints on habitat suitability for benthic invertebrates in gravel‐bed rivers
Authors: Jowett I. G. 
Published: September 2003

AbstractThe primary components of the physical habitat in a stream are water depth, velocity and substrate size, and these appear to be the best predictors of benthic invertebrate distribution within a stream. Substrate stability and fine sediment deposition also influence benthic invertebrate abundance, with reduced abundance where substrates are frequently disturbed or where fine sediment accumulates. Substrate stability and deposition of fine sediment provide hydraulic constraints on habitat suitability and their limits can be predicted by hydraulic formulae. Hydraulic conditions near or at the surface of the stream bed may have a more direct influence on benthic invertebrates than either water depth or mean velocity in the water column above them. If benthic invertebrates have ‘preferred’ near‐bed conditions, hydraulic considerations suggest that optimum mean water velocities for benthic invertebrates should increase with average stream depth and substrate size. Examination of three sets of field data from rivers of varying size showed that benthic invertebrate abundance was strongly related to mean velocity and substrate size, with large differences in habitat use between species. However, although there were large differences in preferred mean velocities between rivers of different size and depth, there was little evidence that this occurred within rivers of similar size and hence little support for the hypothesis that near‐bed hydraulics can provide a generalized method of predicting invertebrate habitat suitability between rivers of different size. Copyright © 2003 John Wiley & Sons, Ltd.
Improvement and optimization of fish guidance efficiency (FGE) at a behavioural fish protection system for downstream migrating Atlantic salmon (Salmo salar) smolts
Authors: Scruton D. A. , McKinley R. S. , Kouwen N. , Eddy W. , Booth R. K. 
Published: September 2003

AbstractA behaviourally based fish protection system was installed in a power canal at a hydroelectric facility on the Exploits River, Grand Falls‐Windsor, Newfoundland, Canada. The river contains an anadromous wild Atlantic salmon (Salmo salar) population in the order of 30 000 returning adults annually. A floating louvre and bypass was installed to protect downstream migrating smolt from entering penstocks and turbines at the end of a power canal at the generating facility. The efficiency and effectiveness of this protection system has been evaluated since 1997 through a combination of conventional tagging (passive integrated transponder, Floy and streamer tags) and use of radio telemetry. Detailed velocity profiling was also conducted along the louvre array, bypass, and throughout the canal to assess the hydraulic performance of the protection system. Initial monitoring in 1997 and 1998 indicated low fish guidance efficiencies (FGEs) for smolt of 25 and 24.3%, respectively. In 1998, a digital spectrum processing (DSP) telemetry system, with multiple antennae, was installed along the louvre array to assist in identification of problem areas where fish were bypassing the louvre. Integration of DSP results with hydraulic monitoring suggested fish loss was associated with hydraulic turbulence and irregularities in the guidance velocities. In 1999, a ‘to scale’ physical model of the power canal, louvre and bypass system was constructed at a hydraulic laboratory to evaluate structural and operational improvements to the system. Field results and hydraulic scale modelling resulted in changes to the canal, louvre angle and bypass entrance, prior to operation in 1999 and 2000. Subsequent monitoring of smolt out‐migration in 1999, 2000 and 2001 indicated substantial improvement in unadjusted FGEs to 54.0, 65.3, and 73.3%, respectively. The paper demonstrates application of the results of detailed monitoring studies, including use of sophisticated telemetry and laboratory hydraulic modelling, for evaluation and optimization of effectiveness of a fish protection system. Copyright © 2003 John Wiley & Sons, Ltd.
A global perspective on environmental flow assessment: emerging trends in the development and application of environmental flow methodologies for rivers
Authors: Tharme R. E. 
Published: September 2003

AbstractRecognition of the escalating hydrological alteration of rivers on a global scale and resultant environmental degradation, has led to the establishment of the science of environmental flow assessment whereby the quantity and quality of water required for ecosystem conservation and resource protection are determined.A global review of the present status of environmental flow methodologies revealed the existence of some 207 individual methodologies, recorded for 44 countries within six world regions. These could be differentiated into hydrological, hydraulic rating, habitat simulation and holistic methodologies, with a further two categories representing combination‐type and other approaches.Although historically, the United States has been at the forefront of the development and application of methodologies for prescribing environmental flows, using 37% of the global pool of techniques, parallel initiatives in other parts of the world have increasingly provided the impetus for significant advances in the field.Application of methodologies is typically at two or more levels. (1) Reconnaissance‐level initiatives relying on hydrological methodologies are the largest group (30% of the global total), applied in all world regions. Commonly, a modified Tennant method or arbitrary low flow indices is adopted, but efforts to enhance the ecological relevance and transferability of techniques across different regions and river types are underway. (2) At more comprehensive scales of assessment, two avenues of application of methodologies exist. In developed countries of the northern hemisphere, particularly, the instream flow incremental methodology (IFIM) or other similarly structured approaches are used. As a group, these methodologies are the second most widely applied worldwide, with emphasis on complex, hydrodynamic habitat modelling. The establishment of holistic methodologies as 8% of the global total within a decade, marks an alternative route by which environmental flow assessment has advanced. Such methodologies, several of which are scenario‐based, address the flow requirements of the entire riverine ecosystem, based on explicit links between changes in flow regime and the consequences for the biophysical environment. Recent advancements include the consideration of ecosystem‐dependent livelihoods and a benchmarking process suitable for evaluating alternative water resource developments at basin scale, in relatively poorly known systems. Although centred in Australia and South Africa, holistic methodologies have stimulated considerable interest elsewhere. They may be especially appropriate in developing world regions, where environmental flow research is in its infancy and water allocations for ecosystems must, for the time being at least, be based on scant data, best professional judgement and risk assessment. Copyright © 2003 John Wiley & Sons, Ltd.