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River Catchment (river + catchment)

Distribution by Scientific Domains

Life Sciences	42%
Engineering	22%
Earth and Environmental Science	22%
Humanities and Social Sciences	5%
2 Other Domains	9%

Selected Abstracts

Comparison of 85Kr and 3H Apparent Ground-Water Ages for Source Water Vulnerability in the Collyer River Catchment, Maine,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2008
William C. Sidle
Abstract:, Apparent ground-water ages as determined by the noble gas isotope 85Kr and the water isotope 3H are compared. Refined gas extraction methodology at the wellhead permits efficient collection of Kr for 85Kr isotope enrichment. 85Kr isochrones elucidate areas of much younger ground-water ages than 3H. Declining 3H activities in the catchment prevent its correlation with the youngest measured 85Kr ages. Source water for most drinking water supplies in the Collyer River catchment is recharged within 40 years BP (2004). Mean-age (,) transport modeling suggests uncertainty of ground-water ages is greatest in the central basin area. [source]

Rehabilitation of Stream Ecosystem Functions through the Reintroduction of Coarse Particulate Organic Matter

RESTORATION ECOLOGY, Issue 1 2009
Kane T. Aldridge
Abstract In streams, coarse particulate organic matter (CPOM) acts as a substrate for microbial activity, which promotes nutrient retention. However, in urban areas, increased peak flows within streams lead to decreased retention of CPOM. The aim of this study was to investigate whether the reintroduction of CPOM, in the form of leaf litter, into a degraded urban stream would increase biofilm activity and phosphorus retention, two ecosystem functions that reflect the integrity of the ecosystem. Stream metabolism and nutrient retention were assessed in treated (T) and control (C) channels of the Torrens River Catchment, South Australia, before and after CPOM addition. Gross primary production and community respiration (CR) were measured as oxygen production and consumption within benthic chambers. Phosphorus retention was measured through a series of short-term filterable reactive phosphorus (FRP) addition experiments. Before CPOM addition, there were no differences in CR, but C retained 6.8% more FRP than T. After CPOM addition, CR was greater in T than in C (572 and 276 mg O2·m,2·day,1, respectively), and T retained 7.7% more FRP than C. The increase in FRP retention in T compared to C was attributed to phosphorus limitation of the CPOM and increased demand for phosphorus of the attached microbial heterotrophic community. The reintroduction of CPOM into degraded streams will be an important step in the restoration of stream metabolism and nutrient retention. Maintenance of CPOM may be achieved through restoration of riparian vegetation, a reduction in the increased peak flows, and rehabilitation of stream morphology. [source]

Distribution, zoogeography and biology of the Murchison River hardyhead (Craterocephalus cuneiceps Whitley, 1944), an atherinid endemic to the Indian Ocean (Pilbara) Drainage Division of Western Australia

ECOLOGY OF FRESHWATER FISH, Issue 3 2005
M. G. Allen
Abstract , The Murchison River hardyhead (Craterocephalus cuneiceps) is endemic to the extremely arid Indian Ocean (Pilbara) Drainage Division of Western Australia, where it is found in the Greenough, Hutt, Murchison, Wooramel, Gascoyne and DeGrey rivers, but is absent from numerous rivers within its range. The most likely explanation for the disjunct contemporary distribution is that C. cuneiceps has simply never inhabited the rivers from which it is conspicuously absent (e.g. Ashburton and Fortescue). Biogeographical, geological and palaeoclimatic evidence is presented to support this hypothesis. In the Murchison River, breeding was extremely protracted with recruitment occurring throughout the year. The largest female and male specimens captured were 96 mm total length (TL; 7.73 g) and 86 mm TL (5.57 g), respectively. Sex ratio was 1.09 females:1 male. Batch fecundity ranged from 46 to 454 (mean 167.5 ± 25.7 SE). Estimates for the length at which 50 and 95% of females first spawned were 36.4 and 44.3 mm TL, respectively. Craterocephalus cuneiceps is essentially a detritivore, but also feeds on aquatic invertebrates. Rainfall in the Murchison River catchment is unpredictable and pH, salinity and temperature are variable. A specialised diet, small size and young age at maturity and protracted spawning period, coupled with serial spawning and high fecundity, allows the numerical dominance of this species in competitive, harsh, arid and unpredictable desert environments. Resumen 1. Craterocephalus cuneiceps es una especie endémica de las cuencas del Océano Indico (i.e., Pilbara) de Australia Occidental. Se encuentra en los ríos Greenough, Hutt, Murchison, Wooramel, Gascoyne y DeGrey pero está ausente en numerosos ríos dentro de su área de distribución. La explicación más probable para esta distribución separada en la actualidad es que C. cuneiceps no ha habitado nunca los ríos en los que está ausente tales como los ríos Ashburton y Fortescue. Presentamos evidencia bio-geográfica, geológica y paleo-climática para soportar esta hipótesis. 2. En el río Murchison, la reproducción es extremadamente prolongada con reclutamiento a lo largo de todo el año. Los mayores machos y hembras capturados alcanzaron 96 mm LT (7.73 g) y 86 mm LT (5.57 g), respectivamente. La proporción de sexos fue 1.09 hembras: 1 macho. La fecundidad varió entre 46 y 454 (media 167.5 ± 25.7 SE) y la longitudes a la que el 50 y el 95% de las hembras se reproducen por primera vez alcanzaron 36.4 y 44.3 mm LT, respectivamente. 3. C. cuneiceps es esencialmente detritívoro pero también se alimenta de invertebrados acuáticos. La lluvia sobre la cuenca del río Murchison es impredecible y el pH, la salinidad y la temperatura son variables. Una dieta especializada, pequeño tamaño, una edad joven en la madurez, y un período reproductivo prolongado, ademos de una freza seriada y alta fecundidad, permiten la dominancia numérica de la especie en ambientes competitivos, duros, áridos e impredecibles. [source]

Regional development, nature production and the techno-bureaucratic shortcut: the Douro River catchment in Portugal

ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 6 2008
Antonio A. R. Ioris
Abstract The introduction of the Water Framework Directive in Europe represents a unique opportunity to promote more inclusive strategies for the long-term preservation of (socionatural) water systems. However, the analysis of the Portuguese experience, using the River Douro as a case study, reveals still considerable shortcomings in the assessment of problems and the formulation of solutions. Instead of promoting a meaningful dialogue between social groups and spatial areas, there is a systematic attempt to conform to legal requisites by taking a ,techno-bureaucratic' shortcut that largely reproduces the distortions of previous regulatory approaches. Decisions on water management are part of political disputes about regional development and state reform, such as in relation to the provision of water and electricity by public utilities. Nonetheless, these broader issues have been kept tacitly away from the WFD agenda, which has been concentrated on adjusting established procedures to the (formal) requirements of the new regulation. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment. [source]

RIVER CAPTURE, RANGE EXPANSION, AND CLADOGENESIS: THE GENETIC SIGNATURE OF FRESHWATER VICARIANCE

EVOLUTION, Issue 5 2006
C. P. Burridge
Abstract River capture is potentially a key geomorphological driver of range expansion and cladogenesis in freshwater-limited taxa. While previous studies of freshwater fish, in particular, have indicated strong relationships between historical river connections and phylogeographic pattern, their analyses have been restricted to single taxa and geological hypotheses were typically constructed a posteriori. Here we assess the broader significance of river capture among taxa by testing multiple species for the genetic signature of a recent river capture event in New Zealand. During the Quaternary an upper tributary of the Clarence River system was diverted into the headwaters of the Wairau River catchment. Mitochondrial DNA (control region and cytochrome b) sequencing of two native galaxiid fishes (Galaxias vulgaris and Galaxias divergens) supports headwater exchange: populations from the Clarence and Wairau Rivers are closely related sister-groups, whereas samples from the geographically intermediate Awatere River are genetically divergent. The upland bully Gobiomorphus breviceps (Eleotridae), in contrast, lacks a genetic signature of the capture event. We hypothesize that there is an increased likelihood of observing genetic signatures from river capture events when they facilitate range expansion, as is inferred for the two galaxiid taxa studied here. When river capture merely translocates genetic lineages among established populations, by contrast, we suggest that the genetic signature of capture is less likely to be retained, as might be inferred for G. breviceps. Rates of molecular evolution calibrated against this recent event were elevated relative to traditional estimates, consistent with the contribution of polymorphisms to branch lengths at shallow phylogenetic levels prior to fixation by purifying selection and drift. [source]

Biodiversity of Belgian groundwater fauna in relation to environmental conditions

FRESHWATER BIOLOGY, Issue 4 2009
PATRICK MARTIN
Summary 1. The Pleistocene glaciations during the Quaternary appear to have resulted in an impoverished groundwater fauna in northern Europe. Re-colonisation may have occurred either through long-distance dispersal from unglaciated southern areas or from local refugia. 2. The Belgian groundwater fauna was sampled at multiple sites, and its habitats characterised, to assess whether the composition of present-day stygobiotic assemblages can be attributed to either of these mechanisms. 3. A total of 202 sampling sites were selected in four hydrogeographic units of the Meuse River catchment. Sites were equally divided among the saturated and unsaturated zones of fractured aquifers (karst) and within the hyporheic and phreatic zones of porous aquifers. Seventeen environmental parameters were determined in parallel. 4. More than 140 species were recorded, including representatives of the Amphipoda, Cladocera, Copepoda, Hydrachnidia, Isopoda, Oligochaeta, Ostracoda, Mollusca, Syncarida and Nematoda. Thirty stygobiont species were identified, of which 10 species were new to the Belgian fauna, raising the total number of stygobiotic species in Belgium to 41. 5. The frequency of occurrences of stygobiotic species was always low, with 37% of the sampled sites lacking stygobionts. A few species were exclusive to one hydrological zone, although no statistically significant differences were detected in species richness at any of the four hierarchial levels considered (Meuse catchment = region, hydrogeographic units, aquifer type and hydrological zone). 6. Overall, results suggest that the stygobiotic fauna of Belgium is species-poor and mostly comprises widely distributed species with broad ecological tolerances. This supports the view that eurytopic species re-colonised the area by long-distance dispersal from refugia in southern Europe. The virtual absence of endemic species further suggests that the scenario of an ancient fauna that survived in local refugia is of minor importance. [source]

Development of a stable isotope index to assess decadal-scale vegetation change and application to woodlands of the Burdekin catchment, Australia

GLOBAL CHANGE BIOLOGY, Issue 7 2007
EVELYN KRULL
Abstract Forty-four study sites were established in remnant woodland in the Burdekin River catchment in tropical north-east Queensland, Australia, to assess recent (decadal) vegetation change. The aim of this study was further to evaluate whether wide-scale vegetation ,thickening' (proliferation of woody plants in formerly more open woodlands) had occurred during the last century, coinciding with significant changes in land management. Soil samples from several depth intervals were size separated into different soil organic carbon (SOC) fractions, which differed from one another by chemical composition and turnover times. Tropical (C4) grasses dominate in the Burdekin catchment, and thus ,13C analyses of SOC fractions with different turnover times can be used to assess whether the relative proportion of trees (C3) and grasses (C4) had changed over time. However, a method was required to permit standardized assessment of the ,13C data for the individual sites within the 13 Mha catchment, which varied in soil and vegetation characteristics. Thus, an index was developed using data from three detailed study sites and global literature to standardize individual isotopic data from different soil depths and SOC fractions to reflect only the changed proportion of trees (C3) to grasses (C4) over decadal timescales. When applied to the 44 individual sites distributed throughout the Burdekin catchment, 64% of the sites were shown to have experienced decadal vegetation thickening, while 29% had remained stable and the remaining 7% had thinned. Thus, the development of this index enabled regional scale assessment and comparison of decadal vegetation patterns without having to rely on prior knowledge of vegetation changes or aerial photography. [source]

Exploitation of High-Yields in Hard-Rock Aquifers: Downscaling Methodology Combining GIS and Multicriteria Analysis to Delineate Field Prospecting Zones

GROUND WATER, Issue 4 2001
Patrick Lachassagne
Based on research work in the Truyàre River catchment of the Massif Central (Lozàre Department, France), a methodology has been developed for delineating favorable prospecting zones of a few square kilometers within basement areas of several hundred, if not thousand, square kilometers for the purpose of siting high-yield water wells. The methodology adopts a functional approach to hard-rock aquifers using a conceptual model of the aquifer structure and of the functioning of the main aquifer compartments: the alterites (weathered and decayed rock), the underlying weathered-fissured zone, and the fractured bedrock. It involves an economically feasible method of mapping the thickness and spatial distribution of the alterites and the weathered-fissured zone, on which the long-term exploitation of the water resource chiefly depends. This method is used for the first time in hydrogeology. The potential ground water resources were mapped by GIS multicriteria analysis using parameters characterizing the structure and functioning of the aquifer, i.e., lithology and hydrogeological properties of the substratum, nature and thickness of the alterites and weathered-fissured zone, depth of the water table, slope, fracture networks and present-day tectonic stresses, and forecasted ground water quality. The methodology involves a coherent process of downscaling that, through applying methods that are increasingly precise but also increasingly costly, enables the selection of sites with diminishing surface areas as the work advances. The resulting documents are used for ground water exploration, although they can also be applied to the broader domain of land-use management. [source]

Simulation of groundwater dynamics in the North China Plain by coupled hydrology and agricultural models

HYDROLOGICAL PROCESSES, Issue 16 2006
Tadanobu Nakayama
Abstract We simulated the effects of irrigation on groundwater flow dynamics in the North China Plain by coupling the NIES Integrated Catchment-based Ecohydrology (NICE) model with DSSAT-wheat and DSSAT-maize, two agricultural models. This combined model (NICE-AGR) was applied to the Hai River catchment and the lower reach of the Yellow River (530 km wide by 840 km long) at a resolution of 5 km. It reproduced excellently the soil moisture, evapotranspiration and crop production of summer maize and winter wheat, correctly estimating crop water use. So, the spatial distribution of crop water use was reasonably estimated at daily steps in the simulation area. In particular, NICE-AGR reproduced groundwater levels better than the use of statistical water use data. This indicates that NICE-AGR does not need detailed statistical data on water use, making it very powerful for evaluating and estimating the water dynamics of catchments with little statistical data on seasonal water use. Furthermore, the simulation reproduced the spatial distribution of groundwater level in 1987 and 1988 in the Hebei Plain, showing a major reduction of groundwater level due mainly to overpumping for irrigation. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Wavelet analysis of inter-annual variability in the runoff regimes of glacial and nival stream catchments, Bow Lake, Alberta

HYDROLOGICAL PROCESSES, Issue 6 2003
Melissa Lafrenière
Abstract Continuous wavelet analyses of hourly time series of air temperature, stream discharge, and precipitation are used to compare the seasonal and inter-annual variability in hydrological regimes of the two principal streams feeding Bow Lake, Banff National Park, Alberta: the glacial stream draining the Wapta Icefields, and the snowmelt-fed Bow River. The goal is to understand how water sources and flow routing differ between the two catchments. Wavelet spectra and cross-wavelet spectra were determined for air temperature and discharge from the two streams for summers (June,September) 1997,2000, and for rainfall and discharge for the summers of 1999 and 2000. The diurnal signal of the glacial runoff was orders of magnitude higher in 1998 than in other years, indicating that significant ice exposure and the development of channelized glacial drainage occurred as a result of the 1997,98 El Niño conditions. Early retreat of the snowpack in 1997 and 1998 led to a significant summer-long input of melt runoff from a small area of ice cover in the Bow River catchment; but such inputs were not apparent in 1999 and 2000, when snow cover was more extensive. Rainfall had a stronger influence on runoff and followed quicker flow paths in the Bow River catchment than in the glacial catchment. Snowpack thickness and catchment size were the primary controls on the phase relationship between temperature and discharge at diurnal time scales. Wavelet analysis is a fast and effective means to characterize runoff, temperature, and precipitation regimes and their interrelationships and inter-annual variability. The technique is effective at identifying inter-annual and seasonal changes in the relative contributions of different water sources to runoff, and changes in the time required for routing of diurnal meltwater pulses through a catchment. However, it is less effective at identifying changes/differences in the type of the flow routing (e.g. overland flow versus through flow) between or within catchments. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Assessment of spring water quality and quantity, and health implications in Tongaren division, Nzoia River catchment, Kenya

AFRICAN JOURNAL OF ECOLOGY, Issue 2009
G. M. Simiyu
Abstract Spring water is the common source of public water supply in most rural communities of developing countries such as Kenya. The water quality and quantity may be altered due to catchments degradation. This study was carried out in Tongaren division, Nzoia River catchment. The aim of this study was to investigate and map the occurrence and distribution of springs and to determine their water quality and quantity. This study determined the spring water discharge, conductivity, turbidity, total and thermotolerant (faecal) coliforms to assess suitability and sustainability of spring water for safe drinking. Twenty-eight springs were identified and their locations mapped using Global Positioning System (GPS) geo-reference data. Discharge ranged from 0.1 to 3 l s,1, with some drying up during dry season. Total coliform was innumerable in most of the studied springs while thermotolerant (faecal) coliform counts occurred in eight springs, including four protected springs. This poses high risks of water-borne diseases. The water should be filtered and boiled prior to use for drinking. Facilitation of communities enabled development of seven springs to enhance water yield and quality. This study established high potential in the communities to develop springs and utilize the spring water as alternative source of livelihoods. [source]

Comparison of 85Kr and 3H Apparent Ground-Water Ages for Source Water Vulnerability in the Collyer River Catchment, Maine,

Preliminary investigation into the prevalence of mucormycosis in the platypus (Ornithorhynchus anatinus) in three catchments in north-west Tasmania

AUSTRALIAN VETERINARY JOURNAL, Issue 5 2010
JW Macgregor
Objective To investigate the distribution and prevalence of mucormycosis in platypus (Ornithorhynchus anatinus) from the Inglis, Emu and Black-Detention catchment areas in north-west Tasmania. Procedure A field study was performed and resulted in the examination of 44 wild platypuses; in addition, one dead platypus and two live platypuses were examined after they were independently submitted to a local veterinary clinic. Results No cases of mucormycosis were conclusively diagnosed. One platypus with signs consistent with those previously described in cases of mucormycosis was captured in the Emu River catchment. However, laboratory tests did not provide a definitive diagnosis for the lesion. Two platypuses from the Inglis catchment area had signs very similar to those previously described in cases of mucormycosis, but laboratory tests found Corynebacterium ulcerans to be the likely cause of the cutaneous ulcers on one of these platypuses and an unidentified fungal agent to be the cause of a cutaneous nodule in the other. Conclusions These findings do not prove that mucormycosis is absent from the populations studied. However, they may indicate that the prevalence of disease is low. The possibility that Mucor amphibiorum is present in a subclinical form in platypuses, or infecting another reservoir, is not excluded. The findings also suggest that caution should be exercised when diagnosing mucormycosis based on clinical findings alone and raise the possibility that some cases may have been incorrectly diagnosed. [source]

Late Cenozoic Geomorphology, Geochronology and Physiography of Yuntaishan in Southern Taihang Mountain, North China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010
Zhonghai WU
Abstract: The late Cenozoic geomorphic features and geochronologic data of the Zhingfang River catchment in the Yuntaishan World Geopark are studied. Several quarternary geochronologic methods, including electron spin resonance (ESR), optically stimulated luminescence (OSL), thermo-luminescence (TL) and U-series are presented in this paper. The results suggest that there are two planation surfaces, named as the Taihang surface which is a peneplain of Taihang stage formed during Oligocene or Oligocene to early-middle Miocene period, and Tang-hien surface which is a mature wide valley of Tang-hien stage formed during late Miocene-Pliocene or Pliocene-early Pleistocene period and probably ended prior to 2.2,2.6 Ma based on ESR dating. After the Tang-hien stage, the incision and aggradation of the river formed six stream terraces with heights of 3,5 m, 8,12 m, 22,24 m, 28,38 m, 50,62 m and 80,85 m above the river bottom, respectively. The dating results of the alluvium sediments suggest that these terraces were formed during Holocene, 20,23 ka B.P., 110,120 ka B.P., 200,240 ka B.P., 840,1200 ka B.P. or ,450 ka B.P. and 1600,1800 ka B.P. or ,1100 ka B.P., respectively. These results indicate that episodic incision of the river, which controls the formation of the scenery in the Yuntaishan World Geopark, was mainly influenced by the periodic dry-wet climate change during late Cenozoic mountain uplift. [source]

Hydrogeological Characteristics of a Karst Mountainous Catchment in the Northwest of Vietnam

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2001
V. T. TAM
Abstract This paper presents a preliminary assessment of the hydrogeological characteristics of a karst mountainous catchment, the Suoi Muoi River catchment, in the northwest of Vietnam. The catchment is located at 600,700 m a.s.l. and covers an area of 284 km. Exposed limestone occupies 32% of the total catchment area. Various types of assessments have been carried out, including geological and hydrogeological field surveys, cave surveys, dye-tracer tests, meteorological and surface water monitoring. Geological studies and cave surveys have identified the most important active cave/conduit systems within the catchment. Although these data are essential, they are insufficient to make a comprehensive appraisal of the hydrologic nature of the catchment under interest. An attempt was made to calculate a global water balance of the catchment, based on short-term (15 months) meteorological and streamflow records. The results show that, despite the existence of a number of substantial cavern conduit systems, the groundwater system of the catchment is governed by the fracture/fissure matrix. The cavern conduit systems only collect groundwater from the adjacent fracture matrix and/or connect topographically isolated surface watercourses. The groundwater storage of the cavern conduit systems appears to be regionally insignificant in comparison with the governed fracture matrix groundwater system. [source]

Predicting river water temperatures using the equilibrium temperature concept with application on Miramichi River catchments (New Brunswick, Canada)

HYDROLOGICAL PROCESSES, Issue 11 2005
Daniel Caissie
Abstract Water temperature influences most of the physical, chemical and biological properties of rivers. It plays an important role in the distribution of fish and the growth rates of many aquatic organisms. Therefore, a better understanding of the thermal regime of rivers is essential for the management of important fisheries resources. This study deals with the modelling of river water temperature using a new and simplified model based on the equilibrium temperature concept. The equilibrium temperature concept is an approach where the net heat flux at the water surface can be expressed by a simple equation with fewer meteorological parameters than required with traditional models. This new water temperature model was applied on two watercourses of different size and thermal characteristics, but within a similar meteorological region, i.e., the Little Southwest Miramichi River and Catamaran Brook (New Brunswick, Canada). A study of the long-term thermal characteristics of these two rivers revealed that the greatest differences in water temperatures occurred during mid-summer peak temperatures. Data from 1992 to 1994 were used for the model calibration, while data from 1995 to 1999 were used for the model validation. Results showed a slightly better agreement between observed and predicted water temperatures for Catamaran Brook during the calibration period, with a root-mean-square error (RMSE) of 1·10 °C (Nash coefficient, NTD = 0·95) compared to 1·45 °C for the Little Southwest Miramichi River (NTD = 0·94). During the validation period, RMSEs were calculated at 1·31 °C for Catamaran Brook and 1·55 °C for the Little Southwest Miramichi River. Poorer model performances were generally observed early in the season (e.g., spring) for both rivers due to the influence of snowmelt conditions, while late summer to autumn modelling performances showed better results. Copyright © 2005 John Wiley & Sons, Ltd. [source]

The response of riparian vegetation to flood-maintained habitat heterogeneity,

AUSTRAL ECOLOGY, Issue 5 2007
BONNIE C. WINTLE
Abstract Riparian environments are subject to the scouring and depositional effects of floods. Riparian vegetation and substrates are scoured during high flows, while litter and sediment is deposited downstream. In the Prosser and Little Swanport River catchments in south-east Tasmania, vascular plant species were surveyed in large riparian relevés. Within these relevés, 1 × 1 m subplots were placed in both flood-scoured and depositional environments. Species composition was compared between these three datasets, to investigate the importance of floods in determining species richness and species composition of riparian vegetation. Species richness and diversity were highest in areas experiencing flood scour. Herbs appear particularly reliant on the creation of gaps for colonization, and some major riparian shrub species may also require disturbance to maintain their abundance. The depositional environment tended to favour shrubs and graminoids. Given that differences in species composition are related to flood-induced features of the riparian environment, the regulation of these rivers might reduce the diversity of the riparian vegetation downstream of dams. [source]

Morphological characteristics of on-farm water storages and their similarity to natural water bodies in the Border Rivers Catchment, Australia

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2010
Susan Lutton
Abstract 1.Natural wetlands throughout the world are under threat from water resource development required to support an ever increasing population. In the Border Rivers Catchment in Queensland, Australia, a large irrigation industry and highly variable flow regime have necessitated the building of large on-farm water storages. With the decline in number and size of natural wetlands, the presence of these storages on the floodplain has raised the question of their suitability as alternative habitat for aquatic fauna. This paper explores the variety of water storage types in the Border Rivers Catchment and how their morphology compares with that of natural wetlands , in particular, factors likely to influence aquatic biodiversity. 2.Storages and natural wetlands formed two distinct groups based on morphology. Storages tended to be large, deep structures with a more regular shape while natural wetlands were irregular and shallow with large perimeters. Although there was a degree of variability amongst the storage sites, a large proportion fell into one group and were considered ,typical storages'. Typical storages contained tailwater and had the following characteristics: situated 3,km from the source river, 10 years old, embankment height of 5,m, area of 400,000,m2, perimeter of 2.5,km and capacity of 1,700,000,m3. 3.Due to their uniform structure we believe that most on-farm storages are unlikely to support as diverse or abundant an aquatic population as natural wetlands. The presence of tailwater and associated chemicals is also likely to reduce the aquatic biodiversity of storages compared with natural wetlands. While they may be unsuitable as replacement wetlands, given their numbers they could provide significant aquatic habitat across the landscape, if managed effectively. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Invertebrate community structure in streams of the Manawatu,Wanganui region, New Zealand: the roles of catchment versus reach scale influences

FRESHWATER BIOLOGY, Issue 8 2004
Russell G. Death
Summary 1. Invertebrate communities at 187 least impacted streams in the Manawatu,Wanganui region of New Zealand were sampled between February and May 2000 to investigate the relative influence of catchment and reach scale environmental influences on community structure. 2. Of the 138 biological (fish and periphyton), local habitat and catchment scale descriptors used to examine invertebrate community patterns, alkalinity and conductivity were the most consistently influential predictors. 3. Of the 52 geographical information system (GIS)-derived catchment variables (catchment geology, catchment land use, rainfall and topography) only per cent catchment in pasture, indigenous forest, coastal sand, crushed argillite and wind blown sand were associated with any measures of the invertebrate communities. 4. Grouping of communities based on GIS data in general, did not generate distinct community types. Groupings based on river catchment, conductivity and alkalinity however, did produce distinct communities. 5. Streams with very low alkalinity were dominated by Ephemeroptera, Plecoptera and Trichoptera that were gradually replaced by Mollusca, Crustacea and Chironomidae as alkalinity increases. 6. Habitat characteristics measured at the scale of the reach were more closely linked with measures of invertebrate community structure than any GIS derived variables or river classifications. [source]

The impact of groundwater,surface water interactions on the water balance of a mesoscale lowland river catchment in northeastern Germany

HYDROLOGICAL PROCESSES, Issue 2 2007
Stefan Krause
Abstract The glacially formed northeastern German lowlands are characterized by extensive floodplains, often interrupted by relatively steep moraine hills. The hydrological cycle of this area is governed by the tight interaction of surface water dynamics and the corresponding directly connected shallow groundwater aquifer. Runoff generation processes, as well as the extent and spatial distribution of the interaction between surface water and groundwater, are controlled by floodplain topography and by surface water dynamics. A modelling approach based on extensive experimental analyses is presented that describes the specific water balance of lowland areas, including the interactions of groundwater and surface water, as well as reflecting the important role of time-variable shallow groundwater stages for runoff generation in floodplains. In the first part, experimental investigations of floodplain hydrological characteristics lead to a qualitative understanding of the water balance processes and to the development of a conceptual model of the water balance and groundwater dynamics of the study area. Thereby model requirements which allow for an adequate simulation of the floodplain hydrology, considering also interactions between groundwater and surface water have been characterized. Based on these analyses, the Integrated Modelling of Water Balance and Nutrient Dynamics (IWAN) approach has been developed. This consists of coupling the surface runoff generation and soil water routines of the deterministic, spatially distributed hydrological model WASIM-ETH-I with the three-dimensional finite-difference-based numerical groundwater model MODFLOW and Processing MODFLOW. The model was applied successfully to a mesoscale subcatchment of the Havel River in northeast Germany. It was calibrated for two small catchments (1·4 and 25 km2), where the importance of the interaction processes between groundwater and surface waters and the sensitivity of several controlling parameters could be quantified. Validation results are satisfying for different years for the entire 198 km2 catchment. The model approach was further successfully tested for specific events. The experimental area is a typical example of a floodplain-dominated landscape. It was demonstrated that the lateral flow processes and the interactions between groundwater and surface water have a major importance for the water balance and periodically superimposed on the vertical runoff generation. Copyright © 2006 John Wiley & Sons, Ltd. [source]

The effects of different input data and their spatial resolution on the results obtained from a conceptual nutrient emissions model: the River Stör case study

HYDROLOGICAL PROCESSES, Issue 18 2005
Markus Venohr
Abstract This paper focuses on the influences of different data sources, and the variation in spatial resolution of input data and analysis, on the calculated nutrient emissions using the conceptual model MONERIS. MONERIS calculates both nitrogen and phosphorus emissions from point and diffuse sources and the riverine nutrient retention. By subtracting the retention from the emissions, a riverine nutrient load was estimated and compared with the observed nutrient river load. All calculations were conducted for the period from 1991 to 1993. The River Stör, with a catchment area of 1135 km2, located in a postglacial lowland landscape in northern Germany, was chosen as a case study area. Two different data sets (e.g. land use, soil type or wastewater treatment plant inventory) were used: a commonly available standard data set (German or European maps) and a more detailed set with a higher spatial resolution derived from several studies at the Ecosystem Research Centre in Kiel. Initially, both data sets were used to apply MONERIS to the total catchment. The results were compared to adapt some of the free model-parameters to the conditions in the relatively small lowland river catchment. Using the standard data set, total nutrient emissions of 2320 tons year,1 of nitrogen and 96 tons year,1 phosphorus were calculated. The detailed data set yielded slightly higher emissions for nitrogen (2420 tons year,1) and for phosphorus (102 tons year,1). According to the spatial resolution, the proportion of the area of tile drainages and sandy soils derived from the different data sets varies considerably. This causes great differences in the total nutrient emissions estimated by the two approaches. Comparing the observed and the calculated nutrient loads, reliable results for catchments larger than 50 km2, or third-order streams, could be shown. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Effects of nitrate nitrogen pollution on Central European unionid bivalves revealed by distributional data and acute toxicity testing

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2010
Karel Douda
Abstract 1.Studies from Central Europe have shown a relationship between the impaired population status of threatened freshwater mussel species and elevated nitrate nitrogen (N,NO) concentrations in running waters. 2.Causal mechanisms, however, remain unknown, and no experimental data or comprehensive studies involving more species are available, which causes uncertainty in prioritizing conservation actions. 3.This study uses both descriptive and experimental approaches to identify the effects of nitrates on freshwater mussels and demonstrates the need for integrating different research methods for development of conservation strategies for threatened species. 4.Spatial co-occurrence of five native freshwater mussel species (Anodonta anatina, Pseudanodonta complanata, Unio pictorum, Unio tumidus, Unio crassus) and N,NO concentrations were examined in a 7th-order river catchment (Lu,nice River, Czech Republic) with anthropogenically-induced increasing N,NO levels and declining populations of these species during the 20th century. 5.Acute toxicity of N,NO was then estimated for artificially reared juveniles of A. anatina and U. crassus using both lethal and sublethal test endpoints. 6.Results showed that the probability of occurrence of all species was significantly reduced in reaches with elevated N,NO levels. 7.In contrast, the results of toxicity testing revealed that the juvenile stages of the two tested species were less sensitive to N,NO than most previously tested freshwater macroinvertebrates. The detected 96-h median lethal N,NO concentrations were two orders of magnitude higher than the limits derived from distributional data. 8.Despite the probable absence of a direct negative effect of N,NO on freshwater mussel populations, N,NO has potential to be used as an effective indicator of biotope conditions. Identification of causal mechanisms responsible for the observed relationship between unionids and N,NO will require further research. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Comparison of sympatric freshwater turtle populations from an urbanized Sydney catchment

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2008
Shelley Burgin
Abstract 1.Australian freshwater turtles are widely distributed throughout the continent, and in each river catchment there are at least two taxa. In south-eastern Australia Chelodina longicollis and forms of Emydura macquarii co-habit within a waterway, although they have been shown to partition habitat within the water column in non-urban bodies of water. Limited comparative data are available for the urban populations. 2.Within urban Sydney C. longicollis (eastern long-necked turtle) and Emydura macquarii dharuk (Sydney short-necked turtle) share habitat. However, in contrast with non-urban studies of C. longicollis and other sympatric E. macquarii taxa, it was observed that the population profile of the two species was similar at all sites, and that C. longicollis were present in greater numbers than E. m. dharuk. 3.The continued degradation of preferred habitat, low recruitment, and potential competition from introduced turtles place both species in a precarious position. 4.The shallow, impounded waterways of the regulated urban bodies of water align more closely with the preferred habitat of C. longicollis than with that of forms of E. macquarii, which prefer deeper flowing waters or large wetlands adjacent to rivers. Emydura m. dharuk may be at greatest risk of extinction in urban areas. 5.Across urban Sydney, the low numbers of E. m. dharuk compared with C. longicollis may be due to the lack of mobility of E. m. dharuk such that individuals tend to be stranded in sub-optimal habitat. In contrast, C. longicollis has a greater propensity for overland movement, and a preference for the ,new habitat' resulting from urban impacts on the associated waterways, and thus appears to be able to utilize these modified urban waters more successfully. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Aerial photosieving of exposed gravel bars for the rapid calibration of airborne grain size maps

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2010
Stephen J. Dugdale
Abstract In recent years, fluvial remote sensing has seen considerable progress in terms of methods capable of system scale characterisation of river catchments. One key development is automated grain size mapping. It has been shown that high resolution aerial photography can be used to automatically produce grain size maps over entire rivers. However, current aerial grain size mapping procedures all require field calibration data. The collection of such data can be costly and problematic in the case of remote areas. This paper presents a method developed to remove the need for field based calibration data. Called ,aerial photosieving', this method consists of using the same very high resolution aerial imagery intended for grain size map production to visually measure particle sizes on-screen in order to provide calibration data. The paper presents a rigorous comparison of field-based photosieving calibration data and aerial photosieving calibration data. Statistical tests are used to demonstrate that aerial photosieving gives similar results when compared with field-based data with only a slight systematic overprediction. The new aerial photosieving method therefore simplifies the overall procedure required for the production of grain size maps and thus improves the cost-effectiveness and potential availability of this new fluvial remote sensing technology. Copyright © 2010 John Wiley &Sons, Ltd. [source]

Scale-dependent controls upon the fluvial export of large wood from river catchments

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2009
Jung Il Seo
Abstract The annual fluvial export of large wood (LW) was monitored by local reservoir management offices in Japan. LW export per unit watershed area was relatively high in small watersheds, peaked in intermediate watersheds, and decreased in large watersheds. To explain these variations, we surveyed the amount of LW with respect to channel morphology in 78 segments (26 segments in each size class) in the Nukabira River, northern Japan. We examined the differences in LW dynamics, including its recruitment, transport, storage, and fragmentation and decay along the spectrum of watershed sizes. We found that a large proportion of LW produced by forest dynamics and hillslope processes was retained because of the narrower valley floors and lower stream power in small watersheds. The retained LW pieces may eventually be exported during debris flows. In intermediate watersheds, the volume of LW derived from hillslopes decreased substantially with reductions in the proportion of channel length bordered by hillslope margins, which potentially deliver large quantities of LW. Because these channels have lower wood piece length to channel width ratios and higher stream power, LW pieces can be transported downstream. During transport, LW pieces are further fragmented and can be more easily transported. Therefore, the fluvial export of LW is maximized in intermediate watersheds. Rivers in large watersheds, where the recruitment of LW is limited by the decreasing hillslope margins, cannot transport LW pieces because of their low stream power, and thus LW pieces accumulate at various storage sites. Although these stored LW pieces can be refloated and transported by subsequent flood events, they may also become trapped by obstacles such as logjams and standing trees on floodplains and in secondary channels, remaining there for decades and eventually decaying into fine organic particles. Thus, the fluvial export of LW pieces is low in large watersheds. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Changes in fish assemblages in catchments in north-eastern Spain: biodiversity, conservation status and introduced species

FRESHWATER BIOLOGY, Issue 8 2010
ALBERTO MACEDA-VEIGA
Summary 1. North-eastern Spain is a hot spot for the introduction of alien fish species, and its native fish fauna is one of the most endangered worldwide. We used an extensive data set from 2002 to 2003 and historical information from the area to characterize fish diversity and establish conservation priorities in river catchments. 2. Diversity indices were used to characterize fish diversity at the basin scale. An index of conservation status was applied for each species, which considers the occurrence, abundance and endemicity of each taxon. We used indirect ordination methods to test the relationship among basin features and to identify those variables most correlated with each other. To identify physical, biotic and environmental characteristics that seem to make a basin particularly susceptible to invasion, we performed a step-wise multiple regression to examine the relationship between the number of native, translocated and introduced fish species (including the original native species richness of each basin), and landscape variables. 3. Over a period of approximately 50 years, the mean range size of native fish species has decreased by 60%. The greatest decline occurred in Gasterosteus gymnurus, Anguilla anguilla and Salaria fluviatilis, for which species over 75% of the original distribution area has been lost. The species with the highest conservation index were Gasterosteus gymnurus and Salaria fluviatilis. 4. Basin area and the catchment type explained 70% of variation in native species richness, whereas the number of dams and basin area accounted for more than 80% of variation in the number of introduced species. 5. The original native species richness and the number of introduced species at basin scale were not related, and thus there was no evidence of "biotic resistance" to invasion. The restoration of natural hydrologic processes and the development of specific management tools to protect native species, such as the prioritization of areas for fish conservation and the eradication of local populations of exotic species, are required to restore native fish fauna in these catchments. [source]

An investigation into the prevalence of Renibacterium salmoninarum in farmed rainbow trout, Oncorhynchus mykiss (Walbaum), and wild fish populations in selected river catchments in England and Wales between 1998 and 2000

JOURNAL OF FISH DISEASES, Issue 2 2008
E Chambers
Abstract A cross-sectional survey of Renibacterium salmoninarum infection in farmed rainbow trout (RBT) and wild fish populations was carried out in 10 farms and six river catchments, respectively, in England and Wales. The majority of the wild fish were sampled in 1998 and the farmed fish in 2000. Grayling, Thymallus thymallus, and brown trout, Salmo trutta, were the main wild species sampled. Two fish, one grayling and one salmon, Salmo salar, were R. salmoninarum culture-positive, compared with 40 confirmed polymerase chain reaction-positive wild fish. The highest prevalence of R. salmoninarum infection was found in grayling in rivers with RBT farms with a history of R. salmoninarum infection. One hundred and fifty fish were sampled from each RBT farm, but none of the fish was found to be R. salmoninarum -positive. Evidence was found, for the first time, for the presence of R. salmoninarum in an eel, Anguilla anguilla. [source]

SIMM: An integrated forecasting system for the Mediterranean area

METEOROLOGICAL APPLICATIONS, Issue 4 2007
Antonio Speranza
Abstract Many ,high-impact' meteorological, marine and hydrological events in the Mediterranean area are characterized by horizontal spatial scales of the order of 10,100 km. Such events are, sometimes, driven by complex dynamical processes involving planetary scale atmospheric flows. Several international programs (ALPEX, POEM, MAP, PYREX, MEDEX) have improved the understanding of some of these processes. However, because of the Mediterranean's geomorphological structure, characterized by mountain chains (e.g. the Alps), semi-enclosed sea basins and small river catchments, many problems remain. It is clear that such problems have to be faced in the context of analysis-prediction systems bridging the gap between global and local scales of motion. These systems should allow for an adequate representation of key dynamical processes at all the relevant scales of motion. The Hydro-Meteorological-Marine System (,Sistema Idro-Meteo-Mare', SIMM) is a first step in developing an integrated system, adequately covering all scales of motion from global to local. A short description of the system is presented, highlighting scientific concepts behind design choices. A summary of the results of verification tests is also illustrated, together with a general evaluation of the whole process in planning, developing and running SIMM in order to assist future updates of the system, currently under development. Copyright © 2007 Royal Meteorological Society [source]

Water balance modelling of (Sub-)Arctic rivers and freshwater supply to the Barents Sea Basin

PERMAFROST AND PERIGLACIAL PROCESSES, Issue 3 2005
Eduard Koster
Abstract Recently, changes in the freshwater supply by rivers to the Arctic Ocean have attracted a great deal of attention. However, quantitative assessments of changes in the annual and seasonal discharge regime of (Sub-)Arctic rivers resulting from climate change are still far from accurate. The sensitivity of discharge to potential changes in climate in two river catchments of intermediate size (104,105,km2), the Tana River in northern Fennoscandia and the Usa River in northern Russia, both draining into the Barents Sea Basin, was evaluated using a spatially distributed water balance model. The tentative results show that discharge amounts during peak flow might remain more or less the same or show a slight increase. However, peakflow events are expected to occur about 20 days or more earlier in spring. Concerning annual discharge amounts a strong increase of 25% for the Usa River and even 39% for the Tana River is simulated in conformity with projected increases in precipitation. Obviously, the resulting increases of the annual freshwater influx from the Tana River (from 5.3 to 7.3,km3) and that of the Usa River (from 42 to 52,km3) into the Barents Sea are insignificant in absolute terms. But in relative terms they agree remarkably well with earlier estimates of changes in freshwater inflow by the very large (Sub-)Arctic rivers. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Flash flood forecasting: What are the limits of predictability?

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 622 2007
C. G. Collier
Abstract Flash floods may occur suddenly and be accompanied by other hazards such as landslides, mud flows, damage to infrastructure and even death. In the UK such events are comparatively rare occurring on average only once or twice per year. Warning systems must depend upon the accurate real-time provision of rainfall information, high-resolution numerical weather forecasts and the operation of hydrological model systems in addition to forecast delivery procedures not discussed in this paper. In this paper we review how flash floods are forecast considering the limitations and uncertainty involved in both the meteorological and hydrological aspects of forecasting systems. Data assimilation and the use of ensembles are both key elements across disciplines. Assessing the susceptibility of river catchments to extreme flooding is considered, and statistical methods of estimating the likelihood of extreme rainfall and floods within a changing climate are examined. Ways of constraining flash flood forecasts are noted as one way to improve forecast performance in the future. Copyright © 2007 Royal Meteorological Society [source]