Natural Watercourses Research Articles

Identification and Matching of Environmental Samples for Regulatory Purposes: A Systematic Approach

The NSW Environment Protection Authority (EPA), under its statutory responsibility, must identify uncharacterized materials that are suspected to cause environmental harm. Samples are collected during investigations of discoloration of natural watercourses, odors, atmospheric fallout, dumped waste drums with unknown contents, and unexplained deaths or physical distress of plant and animal species. Laboratory investigations are undertaken in order to facilitate the correct handling and disposal of orphan waste, to determine the source of a substance, or to identify the cause of death or distress to flora or fauna. No formal published procedure, similar to toxicity identification evaluation (TIE) protocols for the identification of unknown samples, exists. Such a procedure needs to consider the diverse nature and complexity of the samples and the extremely large number of possible contaminants. A further complication is that the unknown material is often contained in environmental matrices. This article describes a unique procedure developed by the NSW EPA's Environmental Forensic and Analytical Science Section (EFAS) to identify potentially hazardous unknown substances. The procedure is based on a series of hierarchical flow charts that have been converted into an interactive, web-based, expert system. This system addresses the need for a comprehensive, systematic, and documented procedure to provide scientific rigor, acceptability in legal cases, and a tool for training junior chemists. The system has undergone a successful testing and validation program. Examples of its use in environmental forensic investigations conducted by the NSW EPA are provided. Ongoing development is focusing on the use of chemometric techniques to match a substance mixed in an environmental matrix with a pollutant source.

Development of a generalized multi‐layer model for 3‐D simulation of free surface flows

AbstractA mathematical model was developed for three‐dimensional (3‐D) simulation of free surface flows. In this model, the flow depth is divided into a number of layers and shallow water equations are integrated in each layer to derive the hydrodynamic equations. To give a general form to this model, each layer is assumed to be non‐horizontal with varying thickness in the flow domain. A non‐orthogonal curvilinear coordinate system is employed in the model, to allow for flexibility in dealing with the irregular geometry of natural watercourses.Due to the similarity in governing equations, two‐dimensional (2‐D) depth averaged programs can be developed into a multi‐layer model. The development for a depth averaged program and its numerical scheme is described in this paper.Experimental data and semi‐analytical solutions are used to evaluate the performance of the model. Three different cases of open channel flow are tested: 1‐flow in a straight open channel, 2‐the flow development region in a channel, and 3‐flow in a meandering channel. It is shown that the model has the capability to predict velocity distribution and secondary flows in complex 3‐D flow conditions. Copyright © 2004 John Wiley & Sons, Ltd.

Free percolation and seepage flows from watercourses

Free percolation and seepage flows from natural and artificial watercourses with curvilinear profiles are considered. The rigorous hydrodynamic solution of the problem of free percolation and seepage flow from a watercourse is obtained by representing the watercourse profiles in the plane of the Joukowski variable by means of the equation of a family of lemniscates and using the conformal mapping method. The calculated dependences for determining all the necessary parameters of the seepage flows and constructing the curvilinear watercourse profiles are given. In the case of a circular basis for the shape of the watercourse profile in the plane of the Joukowski variable these dependences coincide with the well-known exact dependences.

Assessing the Effect of Agricultural Production on the Organic and Biogenic Matter Runoff into the Psel River

Variations in the concentrations of dissolved organic and biogenic substances in waters of natural watercourses under the effect of natural and anthropogenic factors are considered. Seasonal and long-term dynamics of these concentrations in 1990–2001 are analyzed. The causes of an improvement in surface water quality are established, and the role of some changes in the agricultural production in the forest–steppe zone of the Central Black Earth Region of Russia is assessed.

INVESTIGATION OF URBAN WATER QUALITY USING ARTIFICIAL RAINFALL

As the concept of sustainable communities is gaining increasing recognition around the world it is of critical importance to investigate the water quality of urban environments. The contamination of waterways in urban communities seriously affects the utility of water for different purposes and degrades the aesthetic value of natural watercourses. Research investigations in the past have generally focused on suspended solids and nutrients, which are relatively easy to monitor. Unfortunately the build-up and wash-off of micro pollutants such as polycyclic aromatic hydrocarbons (PAH) and heavy metals (HM) have received limited research interest in urban water quality research even though these can cause significant health and environmental impacts even at low concentrations. This paper describes how artificial rainfall, using a specially designed highly portable rainfall simulator was employed in order to generate water quality data from urban environments. This approach was adopted in order to investigate the wash-off of pollutants from paved surfaces and to overcome constraints due to the highly unreliable rainfall in South-East Queensland Australia. The rainfall simulator was able to demonstrate its ability to satisfactory simulate natural rainfall in the area. The results obtained confirmed that the rainfall simulator is a reliable tool for urban water quality research and can be used to simulate pollutant wash-off.

Pre‐migratory differentiation of wild brown trout into migrant and resident individuals

In February to March, wild brown troutSalmo truttawere captured by electrofishing in a natural watercourse (tributaries of the River Lille Aa, Denmark), individually tagged (Passive Integrated Transponders), and released. Representatives of the tagged brown trout were recaptured on the release sites in April by electrofishing and eventually caught in downstream smolt traps (‘migrants’) placed in the main river or by electrofishing (‘residents’) on the initial sites in June. Upon each capture, smolt appearance and body size were evaluated, and a non‐lethal gill biopsy was taken and used for Na+,K+‐ATPase analysis. Based on repetitive gill enzyme analysis in individual fish, a retrospective analysis of the rate of development in individual brown trout ultimately classified as migrants or residents was performed. Two months prior to migration, a bimodal morphological and physiological (gill Na+,K+‐ATPase) development concurred and was related to the subsequent differentiation into resident and migratory fractions of each population. This differentiation was unrelated to growth rate and body size of individual fish but skewed in favour of migratory females. Individuals destined to become migrants developed a smolt‐like appearance before the onset of migration and had higher rate of change of gill Na+,K+‐ATPase activity than fish remaining residents. The rate of change of gill Na+,K+‐ATPase activity was independent of the distance migrated to the trap (3–28 km). Thus in bimodal wild brown trout populations a major increase in enzyme activity takes place before migration is initiated and is a characteristic of migratory individuals only.

Naturalization of Drainage Channels in Lithuania and Possibilities of Their Maintenance as Water Recipients

In the process of high expansion of drainage systems and land cultivation, most natural watercourses in Lithuania were converted into drainage channels. They were deprived of all natural riparian vegetation and abiotic conditions that kept up biodiversity, diminished erosion and deflation, induced self-purification of water etc. Thus the re-naturalization of drainage channels is essential. Consequently, to determine the possibilities to combine re-naturalization processes in channels with their function-ability it was examined the tendencies of woody vegetation (WV) spreading and the hydraulic calculation formulas estimating the performance of overgrown channels as water recipients were suggested. As the study results showed, self-restoration of WV was most progressive in forest and outskirt channels. In the field channels WV expansion takes place as well. However, it depends on the distance from a forest, i.e. WV density decreases sharply from 1.17 stems m−2 to background level (c. 0.26 stems m−2) within the space of 300 m. In the paper there is some positive influence of WV cover in view to drainage channel maintenance discussed referring to the results of former studies as well as the publications of other authors. It includes the prevention of bottom silting as well as slope erosion and slide. The formulas estimating conductivity of overgrown channels are based on the balance of forces occurring on the boundaries of overgrown strips of a stream: resistance of tree stems, friction on the slopes, shear stresses that appear when two streams with different velocities are in contact and the horizontal component of the gravity force causing water movement. Some methods of WV cover abundance control are discussed when having assumed self- or artificial restoration of WV in channels to be maintained as recipients is projected.

Leptospirose-infecção e forma subclínica em crianças de Salvador, Bahia

The purposes of this investigation were to identify the frequency and risk factors of leptospiral infection among children aged between 2 and 15 years in Salvador, Bahia, household contacts of patients (index-cases) hospitalized at Couto Maia Hospital due to Leptospira interrogans (ELISA IgM positive). Among 148 household contacts from 25 selected index-cases, clinical and epidemiological data were collected and ELISA IGM and IgG were performed in paired sera (between 20 days) from 73 (49.3%). This diagnostic method divided the 73 household contacts into three groups: group A (acute or recent leptospiral infection), 30 (41.1%) children, group B (not- infected ) 34 (46.6%) and group C, (past infection) nine (12.3%) children. In group A five (16.7%) had cold syndrome simile. No statistically significant difference was found between groups A and B for sex, race, age and presence of pet dog. However, in group A there was a statistically significant predominance (p < 0.05%) of: contact with natural water courses; index-case sibling aged under fifteen years; female sex and over 9 years old; and principally lack of appropiate trash disposal in the residential area. In conclusion, leptospiral infection in children (from 2 to 15 years of age) in Salvador is underestimated, because it is asymptomatic or presents as a cold syndrome simile.

Transverse mixing in sinuous natural open channel flows

Accurate modelling of transport and mixing of solutes within natural watercourses is vital for environmental management. A lack of understanding of the dominant processes, particularly quantification of transverse mixing processes in natural channels, severely limits the accuracy and usefulness of such modelling. This paper presents results from tracer and hydrodynamic studies conducted on a 'natural' channel form under laboratory conditions. The measurements are analysed using the standard method of moments and the variation of the resulting mixing coefficients examined with respect to the variations in the natural channel geometry and hydrodynamic measurements. Normalisation of the resulting transverse mixing coefficients is investigated. The work conclusively shows that the transverse mixing coefficient varies in direct relation to channel curvature, the variation is cyclic with meander geometry.

Human Impacts on Fluxes of Nutrients and Sediment in Waimanalo Stream, O'ahu, Hawaiian Islands

Waimanalo Stream, on the windward side of the island of O'ahu in the Hawaiian Islands, has been greatly altered by human activities. Native riparian vegetation has been removed along much of the course of the stream, and significant sections of the stream have been hardened to control flooding. Absence of shade from riparian vegetation has allowed California grass (Brachia mutica), wild sugarcane (Saccharum officinarum), and other vegetation to proliferate in the stream channel. Some reaches of the stream more closely resemble a wetland than a natural watercourse. During fair weather and moderate storms, this vegetation effectively traps sediment. During a year when rainfall was ~40% below average, dissolved N and P accounted for most of the N and P transported by the stream. N and P content of the suspended solids was comparable with that of terrestrial organic matter, but with a slightly lower N/P ratio, probably due to the high iron content of Hawaiian soils. Concentration of suspended solids in the stream was only about 4% of the average concentration in fluvial systems that discharge to the ocean. Base flow accounted for about 32% of the P, 58% of the suspended solids, and 96% of the N transported by the stream. The very high contribution of base flow to the N flux was apparently related to contamination of shallow groundwater in the lower reach of one tributary, in which nitrate N concentrations during base flow were about 7 mg liter-1. Flux of N in the stream was comparable with the amount of N produced by livestock waste in this predominantly agricultural watershed. Cesspool seepage and/or leaching of N from animal waste into shallow groundwater and seepage of that groundwater into the stream may account for the anomalously high N loading to the stream. Absence of a similarly high P flux probably re- flects the high iron content of Hawaiian soils, which effectively immobilize P in groundwater.

Upwind Schemes with Exact Conservation Property for One-Dimensional Open Channel Flow Equations

In this paper we present an application and extension of the upwind schemes with source terms decomposed, developed by Bermudez, Vazquez, Hubbard, and Garcia-Navarro, to the one-dimensional open channel flow equations with general, i.e., nonprismatic and nonrectangular, geometries. Our specific numerical approximations for terms that appear in these equations and are related to the channel's geometrical properties are quite straightforward and natural, and at the same time respect the balancing of the flux gradient and the source term. As a consequence, the resulting upwind schemes have the exact conservation property. In several test problems we illustrate the achieved improvement, particularly significant for applications to natural watercourses due to their irregular riverbed geometries.

Floating Timber in Northern Sweden: The Construction of Floatways and Transformation of Rivers

Abstract The development of the export-oriented forest industry played an essential role in the industrialisation of Sweden at the end of the nineteenth century. A very important factor was the available watercourses: these could be used to transport timber from inland forests to the sawmills on the coast. The aim of this study is to analyse the transformation of one river in boreal Sweden, the Vindelalven, during 1820-1945, caused by the introduction of large scale floating of timber. The most prominent feature of this development was the exploitation of a landscape without any industrial infrastructure. Production volumes and the scale of production within the forest industry increased radically from the mid-nineteenth century and transformed the landscape of both the forests and the rivers. The transformation of this natural watercourse, by building different kinds of floatway structures and dramatically changing the flow of water, can be divided into four characteristic periods: i) 1820-1850, ii) 1850-1900, iii) 1900-1945, and iv) from 1945 to the end of the log driving era in Vindelalven in 1976. The many different activities and the lengthy time period have resulted in a fundamental transformation of the river and its ecological characteristics, and have therefore left an almost indelible imprint on the river Vindelalven.

Approval of Streambed's Owners Not Required to Move Water

The Court of Appeals of Arizona ruled that the consent of streambed owners is not required before a water supplier may make beneficial use of an existing natural watercourse to move its appropriated water.

‘Torrents of Terror’: the August 1998 Storm and the Magnitude, Frequency and Impact of Major Floods in the Illawarra Region of New South Wales

The Illawarra Region some 80 kilometres south of Sydney is characterised by a prominent coastal escarpment that rises to 700 m within 12 km of the coast and forms a locus for frequent, high intensity rainfall events. One of the most recent recorded events occurred on 17 August 1998 with rainfall intensities at several pluviometers exceeding 120 mm hr‐1 over a duration of one hour, with up to 249 mm falling in 3.5 hours during the main storm burst. Detailed pluviometer data indicate that the storm was non‐stationary and moved down catchment producing a widespread zone of 120 mm hr‐1 intensity rainfall over a 30 minute duration across mid‐lower catchment areas after similar intensity but longer duration rainfall in catchment headwaters. Slope‐area reconstructions of peak discharge indicate that small catchments on the escarpment within the zone of maximum intensity experienced close to 100% rainfall‐runoff relationships, with peak discharges correlated to short duration (&lt;1 hr) peak rainfall intensities. Widespread erosion occurred particularly where urban development had encroached on natural water courses. Debris/hyperconcentrated flows originating from both anthropogenic and natural sediment sources caused damage to urban areas. This paper provides an overview of the spatial and temporal characteristics of the 17 August 1998 storm, the hydrologic and geomorphic response of the streams, and the nature of damage to urban areas. It reassesses the frequency of recent high‐magnitude rainfall/flood events in the region, discussing the relationships between rainfall intensities, estimates of flood magnitudes and stormwater channel capacities.

On the Correlation between Lexical Stability and Word Creation Device

Some of the most striking facts when working with synonyms and lexical fields are that some words are so remarkably frequently used, that they only reluctantly give way to other synonymous words and that some words do not (or at least seldom) die. I will present the results of an investigation of the English nouns in the lexical field ‘natural watercourse’. Put together and viewed diachronically, the lexical fields for ‘natural watercourse’ in the Old English (OE), Middle English (ME) and Modern English (ModE) period are very vast. Almost 200 words can be found for the general sense ‘watercourse’, and over 100 of these can or could be used in the specific sense ‘natural watercourse’. However, for reasons of homogeneity and need of restriction, only native English words and words stemming from native roots were included; consequently, all Celtic, Latin, Scandinavian, French, Dutch, etc. loan words have been excluded. This leaves us with 72 nouns.

High withdrawal ratio implies changed water policy

Shortage of water has been recognised as an important obstacle to development of various sectors of socity, primarily food production, and, to a lesser extent, industrial expansion. Lack of access to safe water for household use is also a significant drawback for human well-being. As a consequence, the effort to withdraw water from streams, lakes and from the ground, has been substantial during recent decades. From a supply augmentation point of view, the past focus on the quantititave aspects of water provision to sectors in society has, no doubt, been successful. The prevailing policy has, however, evolved with scant attention to the threat to water quality degradation which is an inevitable by-product of an intensified water resources utilisation. This is particularly apparent in dry areas where the dilution effect of natural water courses is reduced as a result of increased withdrawals. Another shortcoming of the water supply policy has been a surprising lack of concern about how water is actually being used in various sectors, what relative benefits are generated, and how water is being disposed after use. It is argued in this article that high rates of water withdrawal necessitate a change in water policy. Among other things the connections between water quantity and quality will have to be dealt with and also the allocation of water supply between incompatible and competing water uses.

An improved vertical-axis water-current turbine incorporating a channelling device

Water-Current Turbines (WCTs) are non-polluting electricity generation plants that harness the kinetic energy of natural water courses, using several kinds of rotors. At the School of Engineering of the University of Buenos Aires, researchers are developing a WCT whose particular characteristics improve technical and economic performance. A channelling device, integrated into the flotation system, is used to modify flow conditions in the neighbourhood of the rotor. This system was developed from theoretical modelling and small-scale model testing in a hydrodynamic test canal. The principal advantages of this kind of machine include reduced need for fixed civil works, ease of transport and relocation and autonomous, self-regulated operation, and it is expected to be a low-cost and long-lifetime system.

The Removal of Reservoir Sediment

ABSTRACT Sedimentation of a reservoir created by a dam constructed on a natural watercourse is inevitable. A dam on a river changes the hydraulic characteristics of flow and the sediment—indicating a change in the transport capacity This article explains reservoir silting and assesses the economy of hydraulic resources and design of precise measures to maintain or improve this situation. Estimation of sediment yield is an extremely complicated problem. Reasonable results were obtained in Iran by applying the chasse flushing) method for Sefid Rud Dam. A 1,800 million m 3 reservoir had originally been created at the end of construction of the high dam in 1961. But sediments silted about 800 million m 3 of the reservoir capacity by 1981. During eight years of flushing operations, about 300 million m3 of sediments were removed from the reservoir through five bottom outlets at riverbed level. These outlets can be used for irrigation water intake when none of the five turbines with 165 m3 per second total installed capacity is operating. The outlets are almost evenly distributed along the base of the dam. The total discharge of these outlets at the reservoir normal water level (RNWL) is about 980 m3/s. Erosion plays a significant role in the amount of solids in runoff from the reservoir Measurement of erosion can be done in two ways: (I) metering of solid discharge, and (2) measurement of sedimentation in the reservoir Both procedures have been put into practice in the Sejid Rud Dam project.

Ectoparasite control on sheep farms in England and Wales: the method, type and timing of insecticidal treatment.

The chemical control of sheep ectoparasites raises important environmental, health and welfare issues. There is increasing concern about the possible harmful effects of pesticides on human health and the role of dipping in the contamination of natural watercourses. A longitudinal survey was conducted in 1991, the last year of compulsory dipping for the control of sheep scab, to obtain information about the chemical control of ectoparasites on 485 farms in England and Wales. Organophosphate insecticides were the most commonly used for both summer and compulsory dipping and for spraying sheep, although many of the products used for spraying sheep were not licensed for this purpose. The early pattern of dipping and spraying appeared to follow the pattern of incidence of blowfly strike although more than 40 per cent of sheep were dipped during the first two weeks of the compulsory dipping period. Compulsory dipping for the control of sheep scab was reduced from two dips to one dip between 1988 and 1989 and removed altogether in 1992. The results from the survey were compared with the results of a previous survey and showed an apparent decline in the use of dipping and an increase in the use of alternative methods of control between 1988 and 1991.

The spread of furunculosis in salmonids in Norwegian rivers

Furunculosis was first discovered in a fish farm in Norway in 1964, following the importation of rainbow trout from Denmark. The disease spread to several farms and to wild fish in the River Numedalslågen, occurring there until 1979. It was eradicated at several farms, the last being disinfected in 1969. In 1985, furunculosis was discovered in marine fish farms in Nord‐Trøndelag, following importation of salmon smolts from Scotland. The disease reached Møre og Romsdal in 1988, by which time 32 fish farms were infected in the two counties. By the end of 1992, 550 farms were infected. The disease spread concurrently in natural watercourses, from 22 in 1989, to 74 by the end of 1992. Rapid spread of the disease was associated with several factors including escapes from fish farms, possibly via transport of fish between farms, and natural movement of wild fish in the sea. The disease was not associated with particular physical characteristics in these watercourses, but large aggregations of fish beneath waterfalls combined with high water temperature may trigger disease outbreaks. The ecological consequences of furunculosis are not known. However, some river populations of adult salmon, sea trout and brown trout have suffered. Furunculosis may result in serious negative consequences for populations if a significant number of the brood stock die before spawning.