bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling the effect of groundwater abstraction on salmonid habitat availability in the river Allen, Dorset, England
Authors: Johnson Ian W. , Elliott Craig R. N. , Gustard Alan 
Published: February 2007

AbstractThe River Allen in Dorset, England is regarded as a classic example of a chalk stream and historically has a reputation as a high quality trout and salmon fishery. Since 1946 the Allen has been subject to groundwater abstraction from chalk boreholes situated close to the stream. Significant reductions in salmonid populations in recent years prompted the National Rivers Authority Wessex (now South Western) Region to initiate detailed hydrological, biological and fisheries studies to investigate the perceived problem. As part of these studies the Institute of Hydrology was commissioned to investigate the effect of the historical groundwater abstraction regime on the availability of physical habitat for life stages of trout and salmon (Johnson et al., 1993).The modelling procedure used the instream flow incremental methodology (IFIM) (Bovee, 1982), which was implemented using the physical habitat simulation (PHABSIM) model (Milhous et al., 1984). Outputs from PHABSIM hydraulic models were combined with habitat suitability data for life stages of trout and salmon to develop habitat (weighted usable area) versus discharge relationships. Habitat suitability indices were developed by the National Rivers Authority Wessex Region by snorkelling and wading in a number of chalk streams similar in character to the Allen.To assess the impact of groundwater abstraction on the temporal variation of habitat availability, weighted usable area versus discharge relationships were combined with a 20 year time series of mean monthly historical and ‘naturalized’ flows. The resulting time series of historical and naturalized weighted usable areas were analysed using a standard duration curve program to demonstrate the effect of the abstraction on the availability of habitat for each species life stage considered.
0+ fish assemblages in a sector of the Rhôcne river influenced by the bregniér–cordon hydroelectric scheme
Authors: Peň´z Milan , Jurajda Pavel , Roux Albert Luis , Olivier Jean Michel 
Published: February 2007

AbstractA survey was undertaken to assess the effects of the construction of the Brégnier–Cordon hydroelectric power station in 1984 on the spawning and nursery habitats of the young of the year fish (YOY) in the River Rhǒne floodplain area. No obvious effect could be identified in the most important aquatic habitats studied, possibly due to the downstream drift and dispersion of juvenile fish. Some new habitats were created with a high production capacity, which proved suitable as nursery areas for YOY rheophilous fishes (e.g. riparian zones of the headrace canal and reservoir). The conditions for young fish were also improved in the section of the main channel, now by‐passed, in which the discharge is stabilized and sufficiently high. However, a rapid decline in the abundance and species diversity of YOY fish assemblages was noted in parapotamic side‐arms, caused by the side‐arms drying up and becoming invaded by terrestrial plants. High YOY abundance, indicating good reproductive success, was nevertheless noted in some fishes considered as sensitive to such hydroengineering activities.
Ecological–economic assessment of a sediment‐producing stream behind lower granite dam on the lower snake river, USA
Authors: Brusven Merlyn A. , Walker David J. , Painter Kathleen M. , Biggam Russell C. 
Published: February 2007

AbstractField investigations and simulation modelling studies were conducted on an agriculturally perturbed watershed draining into the regulated Lower Clearwater–Snake Rivers of Idaho and Washington. Ecological–economic analyses were conducted to develop an integrated systems framework to assess the impacts of alternative farming practices on sustainable farming, sediment erosion and stream health on Tom Beall Creek, with ecological implications and consequences to Lower Granite Reservoir on the Snake River. A geographic information system (GIS) was used to spatially delineate field boundaries, soil types, drainage patterns and erosion rates. An AGNPS (agricultural nonpoint source) pollution model was interfaced with the GIS to project water quality impacts of land use in the watershed. The AGNPS model was integrated with a mixed integer linear programming model (MIP) to facilitate modelling cost effectiveness on land as it related to eroded soil entering the receiving streams. Biological health assessment was performed using benthic macroinvertebrates. The biological condition of Tom Beall Creek was rated as slightly and moderately impaired for 1992 and 1993, respectively. A wheat–pea rotation under conventional tillage and cross‐slope farming had the highest weighted average on‐site erosion damage of $20 per ha; the lowest damage was $3.63 per ha using a wheat–barley–fallow rotation with reduced tillage and divided slopes. Simulating a ‘no programme’ policy scenario, the MIP model showed the dramatic impact of the current farm programme with conservation compliance in the region of highly erodible land and high participation rate in the government farm programme. Under current farming practices and > 50 yr spring runoff event, it was estimated that nearly 5000 t of suspended solids would be exported from the Tom Beall watershed. During low flow years, less than 200 t were exported.Sedimentation in Tom Beall Creek is the most debilitating environmental factor impacting the aquatic biota. High erosion rates from all of the anthropogenically impacted streams above Lower Granite Dam tend to shorten the productive storage life of the reservoir, alter the hydroelectric power generating capacity and interfere with the ecological food web and biodiversity. Although the implementation of better conservation practices in anthropogenically disturbed watersheds will not eliminate watershed erosion, it will reduce the frequency and the amounts of sediment dredged from reservoirs in the future, and will reduce on‐site and off‐site costs of erosion and sediment damage.
Geomorphic response to river flow regulation: Case studies and time‐scales
Authors: Church Michael 
Published: February 2007

AbstractRiver regulation imposes primary changes on flow and sediment transfer, the principal factors governing the alluvial channel regime. In this study, the effect of flow regulation is isolated from sediment delivery. Peace River (Q̄ = 1080m3s−1, increasing to 2110m3s−1 downstream) was regulated in 1967 for hydropower. The gravel‐bed reach immediately downstream from the dam has become stable. Gravel accumulates at major tributary junctions, so the river profile is becoming stepped. Further downstream, the river has a sand bed. It can still transport sand, so morphological changes along the channel include both aggradation and channel narrowing by lateral accretation. In the gravel‐bed Kemano River (Q̄ = 150m3s−1), the addition of water by diversion from another river caused degradation when additional bed material was entrained below the inflow point. However, the effect became evident only after many years, when a competent flood occurred. The short‐term response was channel widening. The time‐scale for the response depends on the size of the river and the nature and severity of regulation. In both rivers, significant adjustment will require centuries and will intimately involve the riparian forest.
Changes in the hydrological regime and invasions by plant species along riparian systems of the Adour River, France
Authors: Décamps H. , Planty‐Tabacchi A. M. , Tabacchi E. 
Published: February 2007

AbstractChanges in the hydrological regime affect the phenomenon of invasion by plant species along riparian systems. The dynamics of exotic (non‐native) and native species were examined at five sites that differed in exposure to hydrological disturbance (floods) during three consecutive years (medium, wet and dry years). When considering the disturbance gradient, exotic plants were favoured by direct exposure to floods (main channel) and by high flood frequencies. The response to year to year changes in hydrology was rapid for both native and exotic communities. However, the exotic plants responded more rapidly and were favoured by a dry year. A general framework including human and natural factors involved in invasions by exotic plants along rivers is presented.
Relationships between fisheries and the integrity of river systems
Authors: Welcomme R. L. 
Published: February 2007

AbstractHuman use of river systems has intensified considerably in the last century due to increasing population and the associated higher demand for water through industrial and agricultural technologies. This intensification process has impacted rivers and resident organisms. Natural rivers have rich and varied fish faunas adapted to the variable climate and morphology of such systems. Much of the diversity and resilience can be traced to the connectivity between two very different components, the channel and the floodplain. Fisheries in rivers are as diverse as the fish communities and are adjusted for capturing most species and life stages throughout the year. Fisheries reasonably conducted have proved sustainable with a high rate of catch correlated with the intensity of flooding in the same or preceding years. Fish communities react in a predictable manner to externally imposed stresses, whether eutrophication, induced by humans or natural environmental modification, or fishing, through successive loss of large species and their replacement by smaller, faster growing species. Generally, the overall weight of catch remains little affected by this process until excessive levels of exploitation are reached and the stock collapses. Damage to fish communities through overfishing and environmental modification is widespread. Improvement of the situation demands stricter management of riverine systems through the protection of the few that remain in a relatively pristine state, and those modified should be restored if social, political and economic conditions allow. Should this not be possible, approaches to the mitigation of externally imposed stresses should be sought and applied.
Light availability and growth of wildcelery (Vallisneria americana) in upper Mississippi River backwaters
Authors: Kimber Anne , Owens Jennifer L. , Crumpton William G. 
Published: February 2007

AbstractLarge beds of Vallisneria americana declined in the backwaters of the Upper Mississippi River after a drought that occurred between 1987 and 1989. One hypothesis for this decline is that low light availability may have decreased net photosynthesis to the extent that overwintering tubers were not formed. Following the decline, light availability remained low. To determine what light levels would be necessary for the re‐establishment of Vallisneria in the Upper Mississippi River, the long‐term growth of plants in a backwater lake and in an experimental pond was measured while the surface and subsurface light were monitored continuously. Plants grown from tubers transplanted to 0·5, 1·0 and l·5m depth in the lake grew and produced tubers only at 0·5m depth (9% of surface light). At 1·0 m, light availability was less than 1% of the surface light. Plants grown from tubers in experimental ponds with four shade treatments (2, 5, 9 and 25% of surface light) for the same growing period produced replacement‐weight tubers in 9% light. For a longer growing season, plants also produced replacement‐weight tubers in treatments with at least 5% of surface light.An average light‐extinction coefficient of 4·64 m−1 was calculated for the backwater lake based on continuous data collected during 94 days during the growing season from eight widely separated sites. Using equations based on the average extinction coefficient for the lake and average leaf lengths of plants grown in experimental ponds, we predict that in years with comparable turbidity, plants grown from locally collected tubers will grow and produce replacement tubers only at depths of 0·8 m or less.
Primary production and light dynamics in an upper Mississippi River backwater
Authors: Owens Jennifer L. , Crumpton William G. 
Published: February 2007

AbstractIn nutrient‐rich systems, phytoplankton production is frequently light‐limited and light attenuation can become a critical factor controlling the rates of production, especially in shallow systems subject to wind resuspension of sediments. This study examined the relation between light availability and primary production in Lake Onalaska, a shallow, nutrient‐rich impoundment of the Upper Mississippi River. Continuous water quality monitors recorded dissolved oxygen, temperature and light flux at a network of sites from July to September 1990 and these data were used to estimate the primary production, light availability and light attenuation coefficients. The gross primary production averaged 2·2gCm−2 day−1 and was due almost entirely to phytoplankton. Production was strongly light‐limited, with most of the light attenuation due to non‐algal components, possibly related to wind resuspension in this shallow system. Regression analyses revealed significant effects of wind speed and direction on light attenuation.
Hydrodynamic model of vessel‐generated currents
Authors: Stockstill R. L. , Martin S. K. , Berger R. C. 
Published: February 2007

AbstractThe drawdown and return currents of vessels navigating in channels have previously been described by empirical relations or by using physical models. The empirical solutions are generally limited in scope to idealized channel shapes. Physical models are unrestricted in this respect, but have limitations related to expense and scale effects. In this paper, vessel effects are modelled numerically. The vessel's displacement is represented by a moving pressure field. The movement of the pressure field is spatially varied in time, representing a vessel navigating along a channel. The hydrodynamics are described using the two‐dimensional shallow water equations, which are modified to account for the effects of the imposed pressure field. A Petrov—Galerkin finite‐element scheme using characteristic‐based weighting is used to solve the governing equations. This Petrov—Galerkin test function is specifically designed to model flow fields containing large gradients such as those found in the vicinity of the moving vessel. The numerical results for return flows and water surface elevations are compared with flume results of vessel passages.
Analysis of water level management on the upper Mississippi River (1980–1990)
Authors: Wlosinski Joseph H. , Hill Lara 
Published: February 2007

AbstractManagement at 27 low‐head dams affects water surface elevations for a 1050km stretch of the Upper Mississippi River (UMR) between St Louis, Missouri and Minneapolis, Minnesota. A systemic overview is given of current operating plans at dams on the UMR and historical data are analysed to determine how well the operating plans are being met. Water level elevations at all 27 dams are regulated as a function of discharge, although plans are specific for each dam. The management objective is to maintain a target water level at specific locations (control point) in each impoundment over specific ranges of discharge. The target water level and control point may change as discharge changes in each impoundment. In some of the impoundments water regulation causes drawdowns below the elevation for which the dams were planned, and at other dams no drawdown occurs. During the navigation seasons of 1980 to 1990, water levels were within their target window for an average of 72·5% of the time for 25 dams analysed. Difficulties in meeting targets are caused by winds, local rainfall events, ice dams and rapidly fluctuating discharges from tributaries with upstream reservoirs used for peaking hydropower.
Environmental considerations for assessing dam removal alternatives for river restoration
Authors: Shuman John R. 
Published: February 2007

AbstractDam removal has received increasing attention over the last several years as a viable alternative to rehabilitation of unsafe dams and as an alternative for consideration as many hydroelectric dams come up for relicensing in the USA. The environmental impacts of dams on river ecosystems have been studied far more extensively than have the impacts of removing dams. Comprehensive environmental research is currently being conducted, assessing both the positive and negative impacts of the possible removal of Rodman Dam on the Ocklawaha River, Florida. The 2073 m long and 6·7 m high dam was constructed in 1968, impounding 3642 ha on this 125 km long river. The impacts of dam removal are compared with those expected by retaining and actively managing the reservoir for fish and wildlife. The research approach described here for addressing alternatives is recommended as a holistic procedure in which to make an environmentally based decision regarding dam removal.
Effects of an experimental flood on litter dynamics in the middle rio grande riparian ecosystem
Authors: Molles Manuel C. , Crawford Clifford S. , Ellis Lisa M. 
Published: February 2007

AbstractThe objectives of the study were to measure the effects of an experimental flood on : (1) leaf litter production by the riparian forest; (2) leaf decomposition; and (3) the amount of forest floor organic matter. The study area is located at Bosque del Apache National Wildlife Refuge, approximately 160 km south of Albuquerque, New Mexico. Experimental and reference study sites of about 3·1 ha were both located in cottonwood (Populus fremontii) riparian forests that had not been flooded for approximately 50 years. The experimental and control study sites were sampled for two years before flooding the experimental site. The experimental flood peaked on about 31 May, the average date of peak flow in the 100 year hydrograph for the USGS gauging station on the Rio Grande at Embudo, New Mexico. Litter fall was lower at the flood site than at the control site, whereas the rate of leaf decomposition was higher at the flood site during the period of inundation. However, the flood did not produce a measurable response in standing stock of forest floor litter. This pool of carbon may require the cumulative effects of several years of flooding to show a measurable response.
Water allocation for ecosystem management of the Missouri River
Authors: Hesse Larry W. 
Published: February 2007

AbstractHistorically the hydrograph of the Missouri River had high and low discharge components. Low flows occurred from July through to early March. The period was characterized by declining thalweg velocity, reduced depth and exposed sand bars. Flood control was initiated as early as 1937 when the first mainstem dam was completed: however, it was not until after 1944 that a rigorous effort to control the wild Missouri River occurred. By 1954 sufficient reservoir storage had been built to allow complete re‐organization of the hydrograph to minimize floods and facilitate navigation. The present managed hydrograph (plan III) is compared with four operational alternatives. Plan I was selected by a team of environmental advisers and it was patterned after the natural hydrograph, but with some adjustments to minimize flood damage and to provide only minimal benefits to navigators. Plan II was selected as the preferred alternative in the environmental impact analysis and it was much more sensitive to the preservation of flood control and navigation benefits. Plan IV was a run of the river alternative, but with the reservoirs present, and, finally, plan V was a true run of the river under pre‐dam conditions.
Ecological integrity and fisheries ecology of the Araguaia—Tocantins River Basin, Brazil
Authors: Ribeiro Mauro César Lambert de Brito , Petrere Miguel , Juras Anastácio Affonso 
Published: February 2007

AbstractAn attempt is made to evaluate the present environmental impacts of the Tucuruí dam on the fisheries and ecological integrity of the Araguaia—Tocantins basin. Management and research needs to minimize the impacts from future hydroprojects and increased human activities in the basin are also addressed. The Tocantins and Araguaia fish fauna is not especially rich by Amazonian standards (about 300 species). Total yields are also rather low (about 8800 t/y) in a river stretch of about 2500 km and unique for being concentrated (90%) in the main channel. Fisheries are heavily dependent on migratory fish and may be severely damaged as a consequence of river regulation. Downstream from the Tucurui Dam important fisheries have been drastically reduced (70%), probably by recruitment failure, lower productivity and overfishing. Upstream from the dam, however, fisheries have benefited from the higher productivity of the artificial lake, although this has not compensated for the regional economic shortages. Management based on ‘basinwise’ catch statistics and fish migration research should take account of likely future disruptions of commercial fisheries by the synergistic effects of other planned impoundments, mining, deforestation and uncontrolled sport fisheries in the middle and upper basins.
Population, environment and sustainability: Reconstructing the debate
Authors: Dovers Stephen R. , Norton Tony W. 
Published: February 2007

AbstractThis article seeks to integrate the population‐environment and sustainable development debates within an integrative approach to sustainability. Reference is made to both global and Australian situations. Common constructions of the debates are briefly critiqued. These issues are addressed via an integrative approach to sustainability, which is described through definitions that differentiate sustainability and sustainable development, and a set of principles that support these definitions. The principles include: extending temporal and spatial scales, appreciation of pervasive ignorance and uncertainty, the need for long term social and ecological goals, and greater cognisance of consumption (demand) aspects.
Sustainable health? primary health care and selective alleviation
Authors: Gerhardt Chloe 
Published: February 2007

AbstractThis paper suggests that there needs to be consideration of what is sustainable health, a definition of which should look beyond the feasibility of maintaining biomedically oriented health strategies. Such a definition needs to be located within a health sensitive development framework. The paper examines some of the debates around appropriate primary health care and looks in particular at health programmes aimed at intervening in diarrhoeal episodes.
Sustainable development in a region: A practical approach to targeting environmental impacts
Authors: Hunt Colin 
Published: February 2007

AbstractIn this paper a model is put forward for setting targets for ecologically sustainable development in a region. The approach is practical and should be applicable to any region. A case study approach facilitates the development of the environmental impact model of Ehrlich and Holdren (1974). Targets for a region's population and water quality are discussed in some detail with the help of the model. The region, the far north of Queensland, Australia, is centred on the Cairns district, which is growing rapidly due to tourism, but is impacting surrounding valuable ecosystems. As well as exploring the environmental impacts of change in the interacting variables of population, consumption and technology, the article contains discussion on setting environmental rehabilitation targets. Major regional externalities would be removed by the achievements of regional water quality improvements. However, other externalities could be generated by the imposition of a limit on regional population. A regional inventory is exampled which could form the basis for regional and (collectively) national environmental accounting.