The conceptual subject of this study was to investigate the effects of microbial biofilms of the hyporheic zone of the river Elbe on nutrient dynamics and elimination. This resulted in four aspects, which were carried out separately. One aspect was the investigation of the dynamics of inorganic nitrogen compounds in the upper sediment layers, as highest microbial activity could be expected due to increased import of nutrients. Dissolved oxygen is suggested to control the nitrogen dynamics in the hyporheic zone, as dissolved oxygen in the flowing water varied seasonally and diurnally due to the photosynthetic activity of the algae and infiltrated in the hyporheic zone. The second aspect was the investigation of advective transport of algal cells through porous media. In laboratory columns the retention and retardation of morphological different algae was estimated. In the year 2001, it was possible to use the diving bell of the Office of Water and Navigation Magdeburg. Samples of the river bed at two different sites (Dresden-Übigau and Coswig near Lutherstadt-Wittenberg) were taken. Microbial activity rates, detrital and grain size parameters were detected. This sample material was also used for the detection of the microbial biocoenosis at the two sites. The microorganisms of the flowing water, the interstitial water and associated to the sediment were characterized by means of the fluorescence in situ hybridization (FISH) technique. Multivariate statistical analysis was performed on the FISH data at different spatial and phylogenetic scales. / Das Ziel der vorliegenden Arbeit war die Untersuchung von mikrobiellen Biofilmen in hyporheischen Sedimenten der Elbe sowie deren Auswirkungen auf die Stoffdynamik und die Nährstoffelimination. Daraus ergaben sich vier Teilaspekte, die separat bearbeitet wurden. Ein Aspekt war die Untersuchung der Stickstoffdynamik in den obersten Sedimentschichten, da hier aufgrund des erhöhten Importes von Nährstoffen die höchste mikrobielle Aktivität zu erwarten ist. Wesentliche biologische Steuergröße ist hierbei vermutlich der Gelöstsauerstoff, der saisonal sowie diurnal durch die photosynthische Aktivität der Algen auch die biochemischen Umsätze im hyporheischen Interstitial beeinflußt. Der zweite Aspekt war die Untersuchung des advektiven Transportes von Algen durch poröse Medien. In Laborversuchen wurde die Retention und die Retardation von morphologisch unterschiedlichen Algen untersucht. Im Jahr 2001 konnte der Taucherschacht des Wasser- und Schiffahrtsamtes Magdeburg genutzt werden. Dadurch konnte Probenmaterial aus der Flußmitte an zwei unterschiedlichen Standorten (Dresden-Übigau und Coswig bei Lutherstadt-Wittenberg) entnommen werden. Es wurden mikrobielle Umsatzraten, Detritus- und Korngrößen- Kenngrößen bestimmt. Ebenfalls am Probenmaterial der Taucherschachtaktion wurde die Fluoreszenz in situ Hybridisierung angewendet. Dies ermöglichte eine Bestandsaufnahme der Bakterien sowohl im Freiwasser der beiden Standorte, als auch im Interstitialwasser und den Bakterien assoziiert ans Sediment. Die Ergebnisse wurden auf unterschiedlichen räumlichen und phylogenetischen Ebenen mit multivariaten statistischen Methoden ausgewertet.

Sediment-related issues in reservoirs can often pose significant challenges to their operational effectiveness, sustainability, and environmental impact. Sustainable sediment management can help resolve these issues and extend the lifespan of dams. The reservoir in Andakílsá river in west Iceland is one out of many reservoirs that has experienced sediment-related problems, and in this study, it was evaluated whether a particular sediment management solution called SediCon Sluicer could be a suitable solution for the site. More specifically, evaluate whether the river transport capacity is sufficient to transport the sediments released from the SediCon Sluicer outlet pipe, so they don’t settle and form thick deposit layers in the river bottom. A hydraulic model of the river was set up in a two-dimensional HEC-RAS model (version 6.3.1) and the Manning’s roughness coefficient in the channel calibrated using water level data. The Manning’s value 0.025 was found to best describe the channel roughness. A HEC-RAS 2D Sediment Transport model was then used to simulate different amount of sediments being released into the river for different flow scenarios. A flood event with 95% confidence level to occur once a year was found to have a peak flow of 50 m3/s and have a duration of around 18 hours. However, the average peak flow from the biggest flood events during a 14-year period was found to be 118 m3/s, and that type of flood events can have a duration up to 70 hours. The results from the sediment simulation scenarios showed that for flood events with long duration and high discharge, the yearly accumulated sediments could most likely all be flushed once a year without too much deposit in the river. A shorter flood event, that is almost certain to occur once a year, is not likely to be able to flush out all the yearly accumulated sediments all at once. Perhaps the SediCon sluicer could be operated several times a year, but a more detailed flow frequency analysis must reveal what smaller floods can be expected yearly. This solution could be a suitable option for the river, but more research and analysis need to be performed for a better certainty on the optimal operational range. / Sedimentrelaterade problem i reservoarer kan ofta utgöra betydande utmaningar för vattensystemets effektivitet, hållbarhet och miljöpåverkan. Hållbar sedimenthantering kan hjälpa till att lösa dessa problem och förlänga dammarnas livslängd. Reservoaren i Andakílsá-floden på västra Island är en av många reservoarer som har upplevt sedimentrelaterade problem, och i denna studie utvärderades om en specifik sedimenthanteringslösning kallad SediCon Sluicer kunde vara en lämplig lösning för platsen. Mer specifikt, utvärdera om flodens transportkapacitet på nedströmssidan om reservoaren är tillräcklig för att transportera sedimenten som frigörs från SediCon Sluicers utloppsrör, så att de inte sätter sig och bildar tjocka avlagringslager i flod-botten. En modell över hydraulik och sedimenttransport i floden sattes upp i en tvådimensionell HEC-RAS-modell (version 6.3.1) och Mannings friktionskoefficient i kanalen kalibrerades med hjälp av vattennivådata. Manning-värdet 0,025 visade sig bäst beskriva kanalens grovhet. En HEC-RAS 2D Sediment Transport-modell användes sedan för att simulera olika mängder sediment som släpps ut i floden för olika flödesscenarier. Resultaten från sedimentsimuleringen visade att om sediment släpptes ut en gång om året så krävs en tillräckligt varaktigt högflödesscenario för att få acceptabel transport, medan sedimenten kan avsättas i floden vid kortare händelser. SediCon Sluicer kanske skulle kunna köras flera gånger per år, men en mer detaljerad flödesfrekvensanalys måste i så fall visa vilka sekvenser av mindre översvämningar som kan förväntas årligen. Denna lösning skulle kunna vara ett lämpligt alternativ för floden, men mer forskning och analys behöver göras för att få en bättre säkerhet om det optimala driftområdet.

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Increased sediment loads within river catchments have well-documented detrimental effects on water quality and catchment management plans are required to address reduction and mitigation of these problems. In order to do this it is essential that tools are available that deliver reliable sediment generation data at appropriate temporal and spatial scales. Currently, most sediment generation models do not include bank erosion individually as a sediment source. Therefore, to enable improved accuracy in predictions of future sediment pressures under environmental change, explicit modelling of the rates of sediment production by the bank erosion is required to provide a more complete representation of the catchment sediment budget. In this study, an existing prototype national bank erosion index has been refined. Using Geographical Information Systems (GIS) digitised overlays, channel migration rates were calculated for several UK catchments. Relationships between the rate of channel bank erosion and factors controlling the rates of channel migration were investigated, including channel sinuosity, slope, upstream catchment area, and restriction of migration due to valley width. Significant correlations between bank erosion and sinuosity, upstream area and channel confinement were observed. The non-linear influence of channel planform geometry (curvature and sinuosity) on migration rates was further investigated using an existing meander migration model. A new bank erosion model was developed to incorporate the influence of both channel confinement and sinuosity. As the model incorporates the key physical controls on bank erosion, hence it is expected that it will have wide applicability in catchment- to national-scale bank erosion assessment. A computationally efficient catchment routing model was developed. Data output from a newly developed catchment overland sediment and runoff estimation model (ADAS APT) was used as input to the routing model. The newly developed bank erosion model and an existing floodplain sedimentation model were incorporated within the routing methodology to provide a catchment sediment budget model. The model was applied to the Exe catchment, Devon, UK and validated against observational data. Model estimations of annual sediment generation through bank erosion, sediment deposition on floodplains, and sediment load at the catchment outlet were within the range of observed values. The catchment sediment budget model developed in this thesis provides a more comprehensive representation of catchment sediment processes than existing alternative methodologies.

Doctor of Philosophy / Department of Geography / Melinda D. Daniels / This dissertation increases our understanding of the drivers that shape and maintain grassland streams and their watersheds by examining the influence of grazing management practices on suspended sediment concentrations, bare ground production, and changes to channel geomorphology. Chapter 2 demonstrates that cattle grazing produces significantly higher baseflow suspended sediment concentrations relative to bison grazing. Suspended sediment concentrations within bison-grazed streams are similar to ungrazed streams, indicating that the substitution of cattle for bison has resulted in degradation of baseflow water quality in grassland streams. Burning frequency, discharge, and seasonality are also significant drivers of suspended sediment concentrations, but are generally less influential than grazing treatments. Chapter 3 indicates that high density cattle grazing treatments produce more bare ground within the riparian zones of grassland stream networks, particularly underneath tree canopy cover. The increased bare ground coverage within riparian areas is correlated with increased suspended sediment concentrations during baseflow conditions, while watershed-scale bare ground production is correlated with increased suspended sediment concentrations during storm flow events. Chapter 4 demonstrates channel geometry and sedimentology are significantly influenced by grazing treatments. This dissertation is the first study to comparatively evaluate the relative influence between cattle and bison grazing on stream geomorphology within any environment. Insight gained from this project can be used by public and private land use managers to improve the environmental integrity of native grassland ecosystems.

Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Thesis (PhD (Civil Engineering))--University of Stellenbosch, 2005. / Estuaries are complex water bodies and differ considerably from fluvial river systems. In estuaries the flow reverses regularly due to the tidal currents and flow depths depend primarily on the tides and not the flow. An estuary has two sources of sediment: the river during floods and the ocean that supplies marine sediment through littoral drift which is transported by tidal currents into the estuary. Oversimplified models cannot be used to investigate the hydrodynamics and geomorphology of an estuary due to its complexity. Sedimentation of South African estuaries has created several environmental and social problems. Sediment transport imbalances have been caused by changes in the river catchments such as increased sediment yields and flood peak attenuation due to dam construction. Historically floods used to flush estuaries to maintain the long-term sediment balance in the river-estuary system, but with reduced flood peaks, sediment transport capacities at the estuaries are reduced and flushing efficiency decreased, resulting in marine transport dominating in many estuaries. Two-dimensional (horizontal, 2DH) numerical models have been found to be appropriate tools for studying hydro- and sediment dynamics in SA estuaries. The modelling shows that the sediment balance in the estuary relies on a delicate balance between dominant flood and ebb flows. Although the models performed very well, there are still additional processes to include such as time varying roughness changes and cohesive sediments. For long-term and long reach simulations, onedimensional (or quasi-two-dimensional) models will also be required in future. Mathematical modeling can be used to simulate the flushing of sediments during floods, but attempts should be made to calibrate these models when adequate field data become available in the future. The modelling has shown that floods play a very important part in estuarine sediment transport processes. Physical modelling was undertaken of the breaching of an estuary mouth. The main aim was to illustrate the merits of breaching at higher water levels as well as to investigate the changes in the mouth during breaching. The data obtained from the experiments were used to calibrate and verify a mathematical model. Mathematical modelling of the breaching process at the Klein River estuary confirms what has been observed during numerous breachings in the field, i.e. that breaching at higher water levels and towards the southeast side is more effective. Sediment transport by both waves and currents was investigated. It was found that with increasing wave and stream power, sediment transport rates would increase if both waves and currents travelled in the same direction. In contrast, it seems that with the current direction opposing that of the waves, Hydraulics of Estuarine Sediment Transport Dynamics in South Africa iii greater wave heights resulted in lower sediment transport rates. A new sediment transport equation, based on stream power, wave power, as well as sediment size was calibrated and verified, and compared to the well-known Bijker formula.

Thesis (MEng) -- Stellenbosch University, 2004. / ENGLISH ABSTRACT: East London is situated on the south-eastern, Indian Ocean, coast o f South Africa. The sediment transport regime at East London is quite unlike the regimes at other ports in South Africa. A major ocean current (the Agulhas) flows exceptionally close to the coastline in this area, thus significantly affecting nearshore sediment movements. The proximity o f a strong ocean current opposed to the net longshore drift (wave driven transport) creates an anomalous sediment transport regime in comparison with that found at most coastlines throughout the world. Furthermore, the Port o f East London (Figures 1.1 and 1.2) is the only major river harbour in South Africa, which all results in a very intricate pattern o f sediment movement in the area, making it o f particular interest. The aims o f this thesis are to study the littoral sediment transports at East London, achieve a holistic understanding o f this complex sediment transport regime and to quantify the various transport rates as far as possible. The study area includes the coastal zone between the Goda and Nahoon Rivers (Figure 1.3) with the main focus on the Hood Point to Orient Beach area (Figure 1.4). The offshore marine environmental conditions are also considered as they have a strong influence on nearshore currents, waves and sediment transport patterns. The prerequisite to understanding the sediment transport processes is a thorough investigation o f the relevant coastal processes. Thus, an in-depth study is undertaken o f the physical environmental data/information, nearshore processes and coastal dynamics that determine or topography changes, the wave regime, the Agulhas Current, the nearshore current regime, the continental shelf sediment dynamics, sediment characteristics, seabed features, the Buffalo River, the tides, the wind regime, and coastal morphodynamics. The specific contribution of each aspect of the environmental data/information to the qualitative understanding of the overall sediment transport regime is determined, and the various modes of sediment transport in different areas are quantified. All o f this information is then synthesised into an expose' o f the sediment transport regime at East London, as briefly described in the conclusions (Section 5 and Table XI) and illustrated in Figure 4.30: There is a net longshore transport (wave driven) of about 250 000 m3 to 300 000 m3 per year on average from the Foreshore area towards the head of the main breakwater, with the total transport into the main sand trap and entrance channel areas from the south-west estimated at 275 000 m3/year. In the offshore zone, large amounts of sediment are transported downcoast by means of the strong Agulhas Current, which also has a significant influence on nearshore currents and sediment transport in the harbour entrance area. About 75 000 m3/year of sand is transported into the “Bar” area (the seaward part of the entrance channel) from the north-east with downcoast flowing nearshore currents, which is the predominant current direction. The riverine input into the harbour has been estimated at less than 10 000 m3/year of sand. In this thesis, therefore, the sediment transport regime (and sediment transport balance) is derived fo r East London, providing for the first time a holistic understanding o f the complex sediment transport regime. It is recommended that more field data should be collected on specific aspects of this study and that the longer term effects of major weather systems should be investigated further. The numerical wave modelling should be extended and the integration of field measurements and numerical modelling to predict sediment transport and resultant bottom changes should be assessed in detail. Ultimately, the information contained in this thesis should feed into a wider regional investigation, with the aim of drawing up a sediment budget for the entire “regional macro sedimentary cell” of which the present study area forms a part. / AFRIKAANSE OPSOMMING: sedimentvervoer-regime by Oos-Londen is anders as die by ander hawens in Suid-Afrika. ‘n Hoof oseaan-stroom (die Agulhas) vloei besonder naby aan die kus in die gebied en het gevolglik ‘n beduidende impak op sedimentvervoer-patrone in die nabystrandse gebied. Die direkte teenwoordigheid van ‘n sterk diepwater stroom wat teen die netto (golfgedrewe) langsstrandse vervoer inwerk, veroorsaak ‘n ongewone sedimentvervoer-regime in vergelyking met wat algemeen wereldwyd gevind word. Daarbenewens is die Oos-Londenhawe (Figure 1.1 en 1.2) die enigste groot rivier-hawe in Suid-Afrika. A1 die ongewone toestande lei tot ‘n ingewikkelde patroon van sedimentvervoer in die gebied. Die doel van hierdie tesis is om die sedimentvervoerregime by Oos-Londen te bestudeer, ‘n holistiese begrip van die ingewikkelde sedimentvervoerregime te verkry, en om die verskillende komponente van die sedimentvervoer regime so ver as moontlik te kM’antifiseer. Die studiegebied sluit die kusstrook tussen die Goda- en Nahoonriviere in (Figuur 1.3). Daar word egter op die Hoodpunt tot Orientstrand-gebied gefokus (Figuur 1.4). Die diepwater, mariene omgewingstoestande word ook beskou, aangesien hul ook ‘n groot impak op die nabystrandse strome, golwe en sedimentvervoer-patrone het. ‘n Deeglike ondersoek van die toepaslike kusprosesse is ‘n voorvereiste om ‘n goeie begrip van die sedimentvervoer-prosesse op te bou. Gevolglik is ‘n diepgaande ondersoek gedoen na die fisiese omgewingsdata en -inligting, nabystrandse prosesse en kusdinamika wat die sedimentvervoer-regime bepaal of bei'nvloed. Dit het ondersoeke ingesluit na: onderhoudsbaggervolumes, bodemtopografie veranderinge, die golfklimaat, die Agulhasstroom, die nabystrandse stroom-regime, die sedimentdinamika op die kontinentale plaat, sediment eienskappe, die windklimaat, die geaardheid van bodemvorme, die Buffelsrivier, getyaksie, en kus-morfologie. Daar is bepaal wat elke aspek van die omgewingsdata/inligting bydra tot ‘n kwalitatiewe begrip van die algehele sedimentvervoer-regime. Verder is die verskillende komponente van die sedimentvervoer in verskeie gebiede gekwantifiseer. Al hierdie inligting is toe versoen in ‘n beskrywing van die sedimentvervoer-regime by Oos-Londen, soos wat in die gevolgtrekkings (Deel 5 en Tabel XI) gegee word en in Figuur 4.30 geillustreer word: Daar is ‘n gemiddelde netto golfgedrewe langsstrandse vervoer van ongeveer 250 000 m3 tot 300 000 m3 per jaar vanaf die strandgebied suid van die hawe na die punt van die hoof-golfbreker. Die totale beraamde vervoer vanaf die suidweste na die hoofsandvangput en ingangskanaal-gebied is 275 000 m3 per jaar. In die diepsee word groot hoeveelhede sediment langs die kus af vervoer deur die sterk Agulhasstroom, wat ook ‘n beduidende impak het op nabystrandse strome en sedimentvervoer in die haweingangsgebied. Omtrent 75 000 m3 sand word per jaar na die “Bar”-gebied vervoer vanaf die noord-ooste deur nabystrandse strome wat langs die kus af vloei. Dit is ook die oorwegende nabystrandse stroomrigting (uitgesluit die brandersone). Sawafafsetting in die hawegebied afkomstig van die Buffelsrivier word op minder as 10 000 m3 per jaar geskat. Die sedimentvervoer-regime (en sediment-balans) by Oos-Londen word dus afgelei, en vir die eerste keer saamgesnoer in ‘n bree insig van die komplekse sedimentvervoer-regime. Daar word aanbeveel dat meer velddata verkry moet word oor sekere aspekte van hierdie studie en dat die langtermyn-impakte van groot weerstelsels verder ondersoek word. Die wiskundige golf-modellering moet uitgebrei word en die gesamentlike benutting van veldmetings met wiskundige modellering om sedimentvervoere en gevolglike bodemveranderinge te voorspel, moet deeglik ondersoek word. Uiteindelik behoort die inligting vervat in hierdie tesis in te voer in breer streeks-ondersoeke, met die oog daarop om ‘n sediment-begroting vir die “Ooskaapse makro-sedimentvervoer-regime” op te stel.

Thesis ((MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: When constructing a submarine pipeline, construction teams must work in the hostile environment in the ocean known as the surf zone. The surf zone is the area along a shoreline stretching between the first evident point of wave breaking and the beach line. In order to ensure that the pipeline is shielded from the imposing forces within the surf zone, engineers use a burial technique which leaves the pipeline length in the surf zone buried underneath the active seabed once construction is finished. Thus a temporary surf zone trench is dredged and protected by an open-ended cofferdam built using iron sheet piles. As a result of the incoming wave climate and the surf zone currents created by this wave climate, sedimentation in and around the trench becomes problematic. In this study alternative geometric layouts for the open-ended cofferdam protecting the surf zone trench are investigated, attempting to minimize the sediment build-up in and around the trench. This was done by using both a 3D qualitative physical model conducted at the CSIR in Stellenbosch, and numerical model using MIKE developed by DHI. However, this study only considers sediment build-up and not structural integrity and constructability of the cofferdam designs. Combining the observations of both the physical- and numerical models, a conclusion was drawn that a structure built perpendicular to the shoreline with a 45oextended arm built from the upstream edge of the cofferdam wall, is the most effective. No dimensions are given as the cofferdam design will change depending on the site specific characteristics. Also an increase in structure length will result in the mouth of the structure being located outside the active sediment zone, which leads to a longer period of time before the pipeline pathway is compromised by sediment. / AFRIKAANSE OPSOMMING: Tydens die konstruksie van 'n onderwaterse pyplyn, moet konstruksie spanne in 'n gevaarlike gedeelte van die see werk naamlik die brandersone. Die brandersone kan gedefinieer word as die area tussen die eerste punt waar branders breek en die strandlyn. Om die pyplyn te beskerm teen die kragte wat branders op dit uitoefen, gebruik ingenieurs 'n installasietegniek waar hul die brandersone seksie van die pyplyn onder die aktiewe seebodem begrawe. Om die tegniek te bewerkstellig, grawe kontrakteurs 'n sloot deur die brandersone en beskerm dit met 'n tydelike struktuur bekend as 'n kofferdam. As gevolg van die inkomende branders en die strome wat deur die branders aangedryf word, kan die opbou van sediment in, en rondom die sloot in die brandersone problematies word. Hierdie studie ondersoek alternatiewe uitlegte vir die tydelike kofferdam struktuur met die oog daarop om die opbou van sediment in, en rondom die struktuur te verminder. Die doel was nagestreef deur gebruik te maak van beide 'n 3-dimensionele fisiese model, gebou en gebruik by die WNNR in Stellenbosch, en 'n numeriese model wat op MIKE, ontwikkel deur DHI gedoen was. Let wel die studie het slegs die sediment beweging in die nabye area van die tydelike kofferdam struktuur in ag geneem en nie die praktiese implimentering en strukturele integriteit van die struktuur nie. Deur die observasies van beide die fisiese- en numeriese modelering in ag te neem, is die volgende gevolgtrekkings gemaak. 'n Struktuur wat loodreg met die strandlyn gebou is en met 'n 45o arm wat na die stroom-op kant toe uitstrek, was die mees effektiewe een. Geen dimensies is deurgegee nie aangesien die ontwerp sal verskil afhangende van die spesifieke area waar die projek aangepak word. Daar is ook gesien dat indien die struktuur langer gemaak word, sal die kontrakteur langer tyd h^e voordat daar sediment probleme in die brander sone sloot ondervind sal word.