This work consists of two distinct and separate sections with differing aims and outcomes. Section A is the critical review, which provides a context for the published work presented in Section B. Section A, the critical review, summarises the current literature in the subject area of environmental aspects of river management and sets the research portfolio in context. The physical landscape has been increasingly influenced by a variety of economic and social changes in recent history. During these approximately 6,000 years, human impact on river systems has been substantial and widespread. The environmental changes, that have stressed river systems, have also damaged their value for both human use and environmental functions. Some of these stresses include changes in water quality and quantity, morphological modifications of the channel and/or floodplain, decline of native species and the introduction of alien species. This has led to changes in current river management philosophy, issues and techniques. Section n, the research portfolio of published work submitted as part of this thesis, focuses on the management of some aspects of environmental change within river systems, particularly problems relating to river rehabilitation and the introduction of invasive riparian plant species. Each published paper has its own individual abstract, summarising the key finding of the research. The research portfolio can be divided into three broad sections. The first section, the main published work, includes those papers approved by the University Research Committee as part of the Registration for the degree of PhD by Published Work in May 2000. These papers form the key part of the thesis. They are introduced in the critical review in the blue text boxes, in order of significance to the text discussed and not in chronological order. They are presented in full in the appendices (numbers as shown below) printed on light blue paper. The next section relates to additional relevant published work. These papers are also submitted as part of this thesis, but are considered to be secondary as a result of their date of publication, i.e. prior to 1995. In order to distinguish these papers clearly from the key papers, they are introduced in the critical review in green text boxes and presented in full in the appendices (numbers as shown below), printed on light green paper. The candidate's approximate contribution and the nature of this contribution to each joint paper have been indicated as a percentage and are shown on the title page of each appendix. The third part is other supporting material and is referred to in the critical review through inclusion of orange-brown text boxes. Since these publications consist mainly of consultancy reports and edited books, they are NOT submitted as part of this thesis and are not presented in full in the appendices. If necessary, this material can be made available to the internal and/or external examiners before or during the viva.

The River Roding near Abridge, Essex was monitored during 1979-82 to assess the short-term ecological effects of recent and contemporary river engineering works on a small, rural watercourse. Increased environmental awareness by Thames Water Authority river engineers and scientists resulted in implementation of an ecologically-sensitive flood alleviation scheme which provided an ideal opportunity for a pioneer case study. Sampling procedure was designed to describe aquatic and riparian habitats, flora and fauna along the watercourse. An extensive, 27 Jan survey revealed that the middle Roding was a typical, highly modified clay river, with limited conservation value. Intensive, continuous monitoring was confined to a 5km stretch; with reference to annual variations recorded in a control site, ecological change produced by three phases of engineering works between 1974 and 1980, each involving two-stage flood relief channels, are described. The magnitude of disturbance to the original habitat determined ecological impact. Retention of in-channel and waterside habitats ensured normal vegetation growth the following Spring, benefitting dragonflies and fish; furthermore, the subsequent development of a richer 'channel-margin' flora produced an increase in waterbird territories. By contrast, excavation below water level severely retarded waterside vegetation recovery, while construction of a trapezoidal, concrete-lined channel produced an impoverished environment which greatly reduced habitat diversity. Silting, plus greater aquatic plant growth in response to increased light levels caused by berm excavation, reduced channel discharge capacity, accentuated by dense Phalaris arundinacea stands on unmanaged berms subject to regular summer inundation. An hydraulically efficient two-stage profile which improves riverine wildlife potential could be produced by retention of the original dry-weather channel; excavation, from one bark, of shallow flood berms which remain dry throughout the summer; tree-planting to counter the effects of increased light; sowing low-profile grasses; and regular grazing or cutting of berm vegetation.

Aid In Action Porthcawl (a registered South Wales Charity Organisation) has been carrying out charity work in the town of Rubik in the Mirdita Region of North Albania for many years. Rubik lies within the Catchment of the River Fani which is remote, ungauged and characterised by frequent flooding, erosion and deforestation. Over the years these processes have had a huge environmental and socioeconomic impact on the residents of Rubik. Aid In Action was concerned about this situation and wished to provide a sustainable solution. Following discussions with staff at the University of Glamorgan, it was agreed that a sustainable solution was the development of an integrated hydrological decision support system for the whole River Fani Catchment. Hydrological models can be a valuable tool, providing a common platform for experts, decision-makers and stakeholders for the sustainable management of catchments, especially when used within the framework of a Geographic Information System (GIS). Such models and systems require quantitative data of good quality over appropriate spatial and temporal scales. For remote mountainous ungauged river catchments in developing countries the development of a catchment model and management system is often complicated due to limited availability of such data. Very often, any available data are difficult to obtain; they could, for example, be scattered among local authorities and are generally in the national language of the country concerned, thus adding the challenge of having records translated into the study language. Over the last few decades, advances in hydrological data capture (e.g. using remote sensing) and data management systems (e.g. GIS) have provided opportunities for overcoming some of the challenges of modelling ungauged catchments. However, the data captured is often from different sensors and sources and at different scales. This research project sought out to creatively use multi-source and multi-scale data to develop a GIS based hydrological model of the River Fani Catchment in the North of Albania to provide, a long term solution for the sustainable management of the Fani Catchment, thus improving the quality of life for the residents of Rubik and the rest of the Catchment. Data from various remote sensing sensors (e.g. Landsat, MODIS, ASTER) and other sources such as published maps, limited gauged flow and rainfall records, local library archives, digital datasets (e.g. CORINE and radar rainfall) and interviews with residents were used to develop the integrated GIS-based hydrological (using WMS hydrological modelling environment) and hydraulic (HEC-RAS) model of the Fani Catchment. The model was then used to not only map significant environmental change in the Catchment (e.g. deforestation using various vegetation indices), but also to assess flooding impact and to analyse various “What-if” scenarios of conservation strategies (e.g. deforestation, afforestation and provision of runoff attenuation systems). The results suggest that the changes in vegetation cover (apart from farming practices) are not considerably extensive in the Catchment between 1984 and 2000. It was observed that afforestation as a flooding mitigation measure did not play a decisive role in runoff reduction compared with attenuation measures. This study has demonstrated the effectiveness of remote sensing and GIS in generating quantitative information on land classification, change detection, soil erosion and general catchment management for remote and ungauged catchments in developing countries. This has been particularly so, owing to recent developments in sensor technologies and increasing available datasets from data providers and the global scientific community at little or no cost.

No description available.

No description available.

Maximum equilibrium scour depths, equilibrium scour volumes, and induced equilibrium movements at isolated obstacles on river beds were investigated in clear-water scour. The research was achieved by a systematic flume study based on the results of dimensional analysis of local scour. The main tested obstacles for local scour were cubes. Local scour at a circular cylinder of aspect ratio 1 and a sphere were also examined for comparison with scour at cubes. Each obstacle was placed on a flat movable bed and oriented normal to the incident flow. Non-cohesive uniform medium sand and very fine gravel were used as movable beds. The tested flow conditions were controlled to give many combinations of the relevant dimensionless parameters for local scour: the flow Froude Number, relative obstacle size, and relative roughness of bed material. Water surface profiles and longitudinal velocity profiles along the plane of symmetry, as well as the horizontal velocities near the bed around isolated obstacles on a fixed bed were examined in several runs. For a slightly submerged cube, the path of maximum velocity downstream of the cube moves from the water surface into the lower part of the flow. At a greater distance downstream, the path of maximum velocity tends to move upward toward the water surface. An increase of flow Froude Number leads to a hydraulic jump behind the cube. The relative longitudinal velocity near the bed is increased in this region. The decrease of relative water depth or the increase of flow Froude Number can lead to increased average relative horizontal velocity (V/u) near a cube. The cube has the highest average V/u value, as compared to flow near a circular cylinder and a sphere. The local scour processes and equilibrium scour patterns at isolated cubes on movable beds were also examined. There is not a unique equilibrium scour pattern for clear-water scour at a cube on a movable bed. Equations were developed to predict the maximum equilibrium scour depth and scour volume and the critical condition for incipient motion of bed material at a cube in clear-water scour. As the water becomes relatively deep, the shape effect of the circular cylinder and the sphere become negligible. The major equilibrium movement of a cube on a movable bed due to scour involves longitudinal displacement, vertical settlement, and longitudinal inclination. Equations were developed to predict the equilibrium movement and the critical condition for incipient upstream movement of a cube in clear-water scour. / Graduation date: 1991

Thesis (doctoral)--Åbo akademi, 1772. / At head of title: M.G.H. Reproduction of original from Kress Library of Business and Economics, Harvard University. Goldsmiths'-Kress no. 10865.3-0.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 288-298).

The extreme flooding event that occurred in 2013 in Alberta, Canada was at time the most costly natural hazard event in the nation’s history with damages exceeding $5 billion. Due to this event, an increased effort for flood mitigation strategies began and resulted in the proposal of the Springbank Off-Stream Storage Reservoir to divert and detain Elbow River flow upstream of the City of Calgary. In order to validate the design of the flow diversion structures, a large (1:16) scale physical model was constructed. The model tested among other things, the impact of large woody debris (LWD) on the flow diversion structures. The LWD modelling included a comparison of LWD manufactured from smooth cylindrical dowels versus natural tree limbs of the same dimensions. The results from the physical model led to a series of design changes for the diversion structures that likely would not have been identified without physical modelling. The LWD material comparison demonstrated significantly different behaviours between LWD types. Specifically, LWD manufactured from natural tree limbs was significantly more likely to accumulate in debris dams on the diversion structures. The impact of root wad was also investigated and proved to play a major role in the damming characteristics and blocking probability of debris. Following the physical model investigations, a numerical simulation was completed in order to examine further the hydrodynamic results obtained from the Springbank project. Using TELEMAC MASCARET’s open source free surface flow program TELEMAC 2D, a two dimensional simulation was completed using data from the physical model. Flowrates and velocities from both models were compared and discrepancies between the two are identified. Reasoning for these differences as well as future works for the numerical model are presented.

Flödesdimensionering är något som används världen över när det kommer till konstruktionen och hanteringen av byggnader i vattendrag. I Sverige har flödeskommitén, bestående av SMHI och intressenter från vattenkraftsindustrin, tagit fram flödesdimensioneringsriktlinjerna som blivit praxis för svenska dammägare. Utifrån dessa riktlinjer får dammar olika flödesdimensioneringsklassningar beroende på vad konsekvenserna blir av olika högflöden. Detta arbete bygger på en nyligt genomförd konsekvensutredning på en av Jämtkrafts dammar i mellersta Norrland. Dammen, som går under namnet Damm B i denna rapport, har tidigare haft flödesdimensioneringsklass II men bedöms nu tillhöra flödesdimensionerings klass I. Dammen ska utifrån detta kunna avbörda ett klass I-flöde på 1690 m3/s till skillnad från det tidigare kravet på 1035 m3/s (klass II-flöde). Syftet med denna rapport äratt undersöka vilka effekter den naturliga tillrinningen av dessa och mellanliggande flöden har på olika objekt och områden nedströms Damm B. Med modelleringsverktyget MIKE 11 konstrueras en en-dimensionell flödesmodell för flödessimuleringar och avläsning av vattennivåer. Simuleringarna visar att den största delen av nedströms undersökta objekt påverkas mellan flödena 1100 m3/s och det så kallade 1000-års flödet på 1376 m3/s där risken för människoliv börjar vid det senare. Redan under klass II-flödet sker viss översvämning på de strandnära vägarna i området. Mellan 1100 m3/s samt 1200 m3/s börjar den mindre dammen nedströms (Damm C) riskera att gå till brott för att sedan överströmmas vid 1400 m3/s. Uträkning av skjuvspänningen berättar att det finns erosionsrisker för korndiametrar på upp till ca 2 cm i vissa erosionsbenägna områden. Denna erosionsbenägenhet inträffar för flöden under 1300 m3/s innan dammbrott har skett i Damm C. Vattenytans lutning minskartill följd av en större motdämning vilket därefter orsakar att minskningen av skärspänningen sker snabbare än den ökning som uppkommer till följd av ett stigande vattendjup. Vattenytan stiger dock och berör områden som inte brukar ligga under vatten. Detta kan leda till kornfraktioner som inte har transporteras bort vid tidigare flöden nu riskerar göra detta vilket bland annat kan bilda drivgods. Flödesdimensioneringsriktlinjerna som har tagits fram i Sverige bygger på miljöbalkens allmänna hänsynsregler vilket gör dem till en bra mall för dammägare att följa. När funderingar dock finns att inte bygga ut avbördningskapaciteten helt behöver det funderas på hur mycket ett eventuellt dammbrott skulle påverka den egna anläggningen och förtroendet från myndigheter samt allmänheten. I fallet med Damm B kommer de flesta objekten som undersöks att beröras vid en naturlig tillrinning på 1400 m3/s. Det är därför av intresse att genomföra noggrannare dammbrotts simuleringar för att hitta ett flöde mellan 1400 m3/soch 1690 m3/s där inga större ytterligare konsekvenser från ett dammbrott uppstår. Till följd av de svårheter och osäkerheter som valetav en lägrea vbördningskapacitet medför motiverar denna rapport dock till en utökad kapacitet för ett klass I-flöde i Damm B och undersöka möjligheterna för ökad avbördning vid Damm C. Detta kan även kompletteras med en omfattande samordnad beredskapsplan längs med älven och ett utökat översvämnings-/erosionsskydd på utsatta områden.