This study was initiated to overview the sediment contaminant monitoring data of Kaohsiung Harbour areas collected between 92-97 for assessing the discharge sources of pollution and manipulating the effective management on the dredging of sediment. The harbour areas are surrounded with major industry and become the receiving sites with sewages from the populated city besides the shipping activities. These have impacted the harbour environment and its development for competing against other world shipping harbours. The present research intends to evaluate the proper strategy for dealing with the reduction of pollution source to prevent from further complicated environmental impacts. Approaches for the data assessment include the distribution of heavy metal concentration and its types of contaminants associated the discharge of industrial sources. A total of 20 monitoring stations were examined for the interrelation of metals. The Principal Component Analysis (PCA) of heavy metals in sediment result shows specific site related contaminant point sources and the localization of pollution at the enclosed areas. Lowest contaminant concentrations were observed at the exit of harbour, area A. The B Area including the estuary of Love River, between Love River and the fifth ship irrigation ditch, and the fifth ship irrigation ditch, dominated the highest element concentrations of Hg, Cd, Pb, Zn, As, Al. The C area, including the former town river to the sea, had highest Cr concentration.The sources of pollution are related to electrical plating, metal polishing factory, leather industries and other industrial production. The D area including the heavy industries i.e., Taiwan Ship Building, Taiwan Steel Manufacturing, Ta-Lin Power Station and the major shipping channel, had the highest Cu concentrations. Similarly the E area as the A area, located at the end exit of harbour, had the lowest metal concentrations. These two areas are more subjected to the tide flow than the other survey stations (B, C, D areas) which have the highest contaminant concentrations. Although the harbour authority has carried out the dredging and monitoring annually, there is no enforcement on regulating the discharge of contaminants from the surrounding industrial sites or the lack of the appropriate strategy of pollution reduction for incorporating with the clean up program. This is owing to the non unified authorization between the municipality and harbour bureau. The present study suggests that four steps are needed to cope with harbour sediment contamination to achieve the sustainable harbour development; 1. appropriate pollution reduction program, 2.long term environmental monitoring, 3.an unified authority and 4.a sediment management strategy with proper guidelines to prevent from land based pollution source discharge.

MESHWR / Department of Hydrology and Water Resources Management / This research was aimed at determining the impact of rainfall events on suspended sediment concentration (SSC) and water quality and links to sediment management in Dzindi River Catchment, Limpopo Province. Rainfall events of different magnitudes and duration erode different sediment volumes resulting in significant variation in sediment loads of receiving water bodies. This affects the water quality of such water bodies. Water samples for water quality and suspended sediment measurements were collected after each rainfall event for periods of six and five months, respectively, in two consecutive rainy seasons. The periods were from October 2012 to March 2013 and December 2013 to April 2014. The samples were collected from selected cross-sections at four sites along Dzindi River. Physical water quality parameters or water quality indicators (pH, Electrical conductivity (EC) and turbidity) were measured with multi 340i/set multimeter and Orion Aqua Fast II turbidity meter, as they are the indicators of the overall status of the water quality. Suspended sediment concentration (SSC) for each sample was measured using evaporation method. SSC at each cross section was computed using the mean discharge-weighted formula. Field survey was undertaken to identify land use activities that promote erosion and hence sedimentation. The relationship between SSC and rainfall magnitude was determined using sediment rating curves. Water quality and sedimentation status at each cross-section together with the information from the GIS map aided in identifying and recommending the best sediment management strategies for different sites in the study area. pH values for October 2012 to March 2013 and December 2013 to April 2014 were both higher in the downstream site of the river catchment, which is Manamani site. Lowest pH was found in the upstream and mid-stream sites, which were Dzindi water treatment works (DWTW) and Tshisaulu, respectively. Tshisaulu had highest EC value and Lwandani had lowest value, respectively, for the period of October 2012 to March 2013. DWTW had the highest EC value and Tshisaulu had the lowest EC value, respectively, for the period of December 2013 to April 2014. Manamani had high turbidity value and Lwandani had low turbidity value for October 2012 to March 2013. Turbidity for DWTW for the period of December 2013 to April 2014 was the highest and Tshisaulu had the lowest turbidity value. Sediment rating curves for DWTW, Tshisaulu and Manamani, respectively, had coefficient of determination (R2) values of 0.185, 0.53 and 0.99, respectively. Different sediment management strategies, including slope and bank protection and minimum and mulch tillage, were recommended based on topography and land use activities and these strategies can prevent soil erosion and minimize transport of sediments into the river.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19293号 / 工博第4090号 / 新制||工||1630(附属図書館) / 32295 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 教授 藤田 正治, 准教授 竹門 康弘 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Although sediment is a natural component of stream ecosystems, excess sediment presents a threat to natural freshwater ecosystems. Sediment management is complicated because sediment can be dissolved in the water column, suspended as particles in the water column, or rest on the bottom of the stream bed, and can move between these forms (e.g. bedded sediment can be resuspended). Each form of sediment affects aquatic life in a specific way. To manage stream sediment in a way that protects aquatic life, we need to understand the ways different forms of sediment affect living things, and we need to be able to predict how sediment changes form under different stream conditions (for example, during high water events). To improve our understanding of these things, the studies in this dissertation set out to: (1) identify how often sediment is specifically mentioned as the primary pollutant “stressor” of the benthic macroinvertebrate community (primarily aquatic insects); (2) determine which forms of sediment have the largest negative impacts on aquatic insects in Virginia and what levels of sediment may cause harm; and (3) measure the changes of sediment between suspended and bedded forms in a small stream to provide information needed to restore the health of stream ecosystems. An inventory of published US Clean Water Act Total Maximum Daily Load (TMDL) reports, which states write to identify their impaired waters and their plans to improve those waters, revealed that sediment is an important stressor in over 70% of waters that have altered aquatic insect communities. If the language used to describe how waters are evaluated and what is causing the impairments were standardized among states, data collected under the Clean Water Act could be more broadly used to help understand water quality issues and ways to address them. Analysis of 10 years of Virginia Department of Environmental Quality sediment and aquatic insect community data collected within 5 ecoregions of the state indicates that a combination of 9 sediment parameters reflecting dissolved, suspended, and bedded forms explains between 20.2% and 76.4% of the variability in the health of the aquatic insect community within these regions. Embeddedness, which measures how much larger particles such as gravel and cobble are buried by finer particles like sand; and conductivity, which is a measure of dissolved salts in the water column, both have substantial impacts on the aquatic insect community. Sensitivity thresholds for embeddedness and conductivity indicate the levels of these parameters above which 5% of insect families are absent from a stream; therefore, these levels are considered protective of 95% of the insect community. Thresholds for embeddedness are 68% for the 5 combined ecoregions, 65% for the Mountain bioregion (comprised of Central Appalachian, Ridge and Valley, and Blue Ridge ecoregions), and 88% for the Piedmont bioregion (comprised of Northern Piedmont and Piedmont ecoregions). Thresholds for conductivity are 366 µS/cm for combined ecoregions, 391 µS/cm for the Mountain bioregion, and 136 µS/cm for the Piedmont bioregion. These thresholds can be used by water quality professionals to identify waters with sediment impairments and can be used to help identify appropriate stream restoration goals. A study of sediment movement within the channel of a small stream indicated average transport speeds of ~ 0.21 m/s during floods with peak flows of ~ 55 L/s. The use of rare earth elements (REE) to trace sediment particles revealed individual particle transport distances ranging from 0 m to >850 m. Deposition on a unit area basis was greater in the stream channel than on the floodplain, and the movement of sediment from the stream bed to the water column and back again during sequential floods was evident. Approximately 80% of the tracer was deposited within the first 66 m of the reach. This information can aid the development of models that predict the impact of stream restoration practices on in-stream habitat and improve predictions on the time it will take between the initiation of stream restoration projects and when we see improvements in the biological community. / PHD

Semi-arid environments are mainly characterized by scarce water resources and are usually subject to risks of water stress. In these regions, water supply for drinking and irrigation purposes depends strongly on storage in surface reservoirs and sediment deposition in these reservoirs affects adversely the water storage. In order to reproduce the complex behaviour of sediment deposition in reservoirs located in semi-arid environments and the effects of using sediment management techniques, a reservoir sedimentation model is developed and coupled within the WASA-SED model, which simulates rainfall-runoff processes and sediment transport at the hillslope and river network. The reservoir sedimentation model consists of two modelling approaches, which may be applied according to reservoir size and data availability. For reservoirs with information about their geometric features (reservoir topography, stage-area and stage-volume curves) and physical properties of sediment deposits, such as deposition thickness, grain size distribution of sediment deposits and sediment densities, a detailed modelling approach of reservoir sedimentation may be applied. For reservoirs without those characteristics, a simplified modelling approach is used. The detailed modelling approach of reservoir sedimentation enables the assessment of sediment deposition pattern in reservoirs and the evaluation of sediment release efficiency of sediment management techniques. It simulates sediment transport along the longitudinal profile of a reservoir. The reservoir is divided into cross sections to elaborate the sediment budget. The sediment transport component is calculated using a non-uniform sediment transport approach based on the concept of sediment carrying capacity. Four different sediment-transport equations can be selected for the simulations. The simplified modelling approach of reservoir sedimentation is suitable to simulate water and sediment transfer in dense reservoirs network. Nevertheless, it allows simulating neither sediment management techniques, nor spatial distribution of sedimentation. In this approach, the reservoirs are classified into small and strategic reservoirs according to their location and size. Strategic reservoirs are medium and large-sized reservoirs located on main rivers at the sub-basin’s outlet or reservoirs of particular interest. The small reservoirs are located at tributary streams and represented in the model in an aggregate manner by grouping them into size classes according to their storage capacity. A cascade routing scheme is used to describe the upstream-downstream position of the reservoir classes. The water and sediment balances of small reservoirs are computed for one hypothetical representative reservoir of mean characteristics. Sediment trapping efficiency and effluent grain size distribution are estimated using the overflow rate concept. Three model applications are carried out within this research, as follows: • The detailed modelling approach of reservoir sedimentation is applied to the 92.2 Mm³ Barasona Reservoir, located in the foothills of the Central Pyrenees (Aragon, Spain). A two-stage calibration was performed to account for changes on the sediment deposition pattern caused by sediment management. The reservoir sedimentation model is then validated for another simulation period which confirms that the processes related to reservoir sedimentation are well represented by the model. • An application is carried out to the 933-km² Benguê catchment, located in the semi-arid region of Northeast Brazil. The catchment is characterized by a dense reservoir network, covering almost 45% of the catchment area, with a significant lack of data. Water and sediment balances of those reservoirs are computed using the simplified modelling approach. Three spatial configurations describing the cascade routing scheme are tested. • The reservoir sedimentation model is applied again to the Barasona reservoir to evaluate the sediment release efficiency of sediment management strategies. Cost analysis is presented to help in the choice of the most promising sediment management technique for that situation. Thus, the model enables the assessment of technical features of the sediment management strategies. Overall, simulation results are characterized by large uncertainties, partly due to low data availability and also due to uncertainties of the model structure to adequately represent the processes related to reservoir sedimentation. / Semiaride Gebiete sind hauptsächlich durch geringe Wasserressourcen gekennzeichnet und unterliegen häufig dem Risiko der Wasserknappheit. In diesen Gebieten ist die Wasserbereitstellung für Bewässerung und Trinkwasserversorgung stark von der oberflächlichen Speicherung in Stauseen abhängig, deren Wasserverfügbarkeit nachteilig durch Sedimentablagerung beeinflusst wird. Zur Wiedergabe des komplexen Sedimentablagerungsverhaltens in Stauseen von semiariden Gebieten und die Auswirkungen von Sedimentmanagementmaßnahmen wird ein Sedimentationsmodell entwickelt und mit dem WASA-SED Modell gekoppelt, das für die Modellierung der Abflussbildung und des Sedimenttransportes in Einzugsgebieten geeignet ist. Das Sedimentationsmodell beinhaltet zwei Ansätze, die unter der Berücksichtigung verschiedener Stauseengrößenklassen und Datenverfügbarkeit eingesetzt werden können. Für die Stauseen mit verfügbaren Informationen über ihre geometrischen Eigenschaften (wie Stauseetopographie und Höhe-Fläche-Volumen-Beziehung) und weitere Kenngrößen wie Ablagerungsmächtigkeit, Korngrößenverteilung und Sedimentdichte, kann ein detaillierter Modellansatz für die Sedimentablagerung verwendet werden. Wo diese Informationen nicht verfügbar sind, wird auf einen vereinfachten Ansatz zurückgegriffen. Der detaillierte Modellansatz ermöglicht die Betrachtung von Ablagerungsmustern im Stausee und Einschätzungen über die Effektivität von Sedimentmanagementmaßnahmen hinsichtlich der Sedimententlastung. Dieser Ansatz beruht auf der Simulation des Sedimenttransportes entlang eines Stauseelängsprofils. Für die Berechnung des Sedimenttransfers wird der Stauseekörper in einer Folge von Querprofilen repräsentiert. Der Sedimenttransport wird dabei korngrößenspezifisch entsprechend der Transportkapazität berechnet. Dafür stehen vier verschiedenen Sedimenttransportgleichungen zur Verfügung. Der vereinfachte Modellansatz ist für die Simulation des Sedimenttransfers in Gebieten mit hoher Stauseedichte geeignet, jedoch können weder Sedimentmanagementmaßnahmen noch die räumliche Verteilung der Ablagerungen berücksichtigt werden. Dafür werden die Stauseen in Abhängigkeit von ihrer Größe und Position in kleine und strategische Stauseen unterteilt. Dabei sind strategische Stausseen solche mit mittlerem bis großem Volumen sowie einer Lage im Hauptgerinne oder solche mit sonstiger besonderer Bedeutung. Kleine Stauseen hingegen befinden sich an den Nebenflüssen und werden im Modell in aggregierter Form durch ihre Einteilung in Stauseegrößenklassen repräsentiert. Ein Kaskadenverfahren wird für den Wasser- und Sedimentlauf zwischen den Stauseeklassen verwendet. Dabei werden für jede Stauseeklasse der Wasser- sowie Sedimenthaushalt für einen hypothetischen repräsentativen Stausee mit mittleren Eigenschaften berechnet. Die Sedimentaufnahme und die Korngrößenverteilung des abgegebenen Sediments werden mit dem Überlaufanteil-Ansatz berechnet. In dieser Studie werden drei Modellanwendungen vorgestellt: • Für den 92,2 Mio.m³-großen Barasona-Stausee (Vorland der Zentralpyrenäen, Aragon, Spanien) wird die Modellierung der Sedimentablagerung mit dem detaillierten Modellansatz vorgenommen. Die Kalibrierung dafür wurde in zwei Schritten durchgeführt, um Änderungen im Stauseemanagement Rechnung zu tragen. Die ModellValidierung wird schließlich für eine andere Simulationsperiode vorgenommen. Dabei wird ersichtlich, dass die Prozesse der Sedimentablagerung gut durch das Modell wiedergegeben werden. • Das Modell wird auf das 933 km²-große Benguê-Einzugsgebiet, das sich im semiariden Nordosten Brasiliens befindet, angewendet. Dieses Einzugsgebiet ist durch eine hohe Dichte an kleinen Stauseen, charakterisiert, die fast 45% des Gebietes umfasst, wofür jedoch wenige Messdaten verfügbar sind. Deshalb werden der Wasser- und Sedimenttransport mit dem vereinfachten Modellansatz berechnet. Dabei werden drei Konfigurationen des Kaskadenverfahrens getestet. • Die Modellanwendung erfolgt erneut für den Barasona-Stausee bezüglich der Effektivität der Sedimentmanagementmaßnahmen. Eine Kostenanalyse ermöglicht die Auswahl geeigneter Maßnahmen für den Stausee. Dadurch wird eine Beurteilung der verschiedenen Sedimentmanagementstrategien ermöglicht. Im Allgemeinen unterliegen die Simulationsergebnisse großen Unsicherheiten, teilweise wegen der geringen Datenverfügbarkeit, andererseits durch die Unsicherheiten in der Modellstruktur zur korrekten Wiedergabe der Sedimentablagerungsprozesse.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20678号 / 工博第4375号 / 新制||工||1680(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 中川 一, 教授 平石 哲也, 准教授 川池 健司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Reservoir sedimentation occurs as dams impound streams and rivers, preventing the delivery of sediments downstream. Globally, reservoirs lose approximately 40 million acre-ft of storage to sediments each year. Several methods for managing reservoir sedimentation have been developed to help extend project life. In 2017, the World Bank sponsored REServoir CONservation (RESCON) 2, a pre-feasibility program aimed to help users select sediment management practices to consider for more detailed studies.There are two main objectives to this research: 1) perform a sensitivity analysis to understand which parameters require greater precision and which can be roughly approximated, and 2) evaluate RESCON 2 suggested practices to assess the model's accuracy and consistency for providing the optimal solution. Comparisons of the actual sediment management practice will be made with RESCON's results and applicable zones from the Sediment Management Options Diagram (SMOD). Brief descriptions of the SMOD and RESCON 2 will be provided. RESCON-required inputs will be summarized, and some key entries will be presented. Additionally, innovations taken in Japan to modify and retrofit exiting reservoirs with sediment management capabilities will be explored.The sensitivity analysis proves the unit benefit of reservoir yield parameter to be highly sensitive, and users should invest time into determining this value. The sensitivity analysis also illustrates certain processes in RESCON, such as automatically determining the implementation schedule of flushing or a sustainable solution for dredging operations, have great influence over the respective method's analysis. Approximations can be used if these options were selected.Twenty reservoirs from around the world were modeled in RESCON 2, with storage capacities ranging between 152 acre-ft and 31.9 million acre-ft. All sediment management alternatives whose NPV lied within 30% of the highest alternative were deemed practicable for the reservoir. Of the twenty models analyzed in RESCON 2, ten did not practice sediment management. Analyzing only those reservoirs where sediment management is being employed, RESCON predicted the correct or used practice eight out of ten times.Recommendations to improve RESCON include 1) an HSRS operations and maintenance parameter, 2) expanding the unit benefit of reservoir yield parameter into several terms to more explicitly state applicable revenue sources, and 3) creating a list of RESCON model builds, updates, and bug treatments and an option for users to report bugs or other problems.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23862号 / 工博第4949号 / 新制||工||1773(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 准教授 竹門 康弘, 准教授 Kantoush Sameh / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15315号 / 工博第3194号 / 新制||工||1481(附属図書館) / 27793 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 角 哲也, 准教授 竹門 康弘, 准教授 武藤 裕則 / 学位規則第4条第1項該当