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The effectiveness of temporary flood protection is highly variable depending on the location, application, and the nature of flood events. This thesis evaluates sand-filled geotextile containers used as flood protection products within a framework of standardized tests. Specifically, Syn-Tex Wave Breakers and Super Sandbags are tested in both laboratory and field settings to quantify seepage rates, stability and durability. This allows informed decisions to be made regarding appropriate applications for each temporary flood protection product, and identifies areas for product improvement and development. The products tested performed well over the range of loading conditions applied. Large sand-filled geotextiles would be well-suited for situations where stakeholders have a low tolerance for risk, and there is adequate site access for the construction equipment required for installation. An ideal installation would be a long, relatively straight stretch where vertical product/wall and product/product interfaces can be minimized.

Der Projektabschlussbericht befasst sich mit der Bestimmung von Hochwasserscheitelabflüssen mit zugeordneter Jährlichkeit HQT an unbeobachteten Gewässerquerschnitten in Sachsen. Grundlage sind beobachtete Hochwasserscheitel an 113 Pegeln und hydrologische Überlegungen zur räumlichen Variabilität von Hochwassern. Zur Anwendung kommen Index-Flood-Verfahren, Top-Kriging und Georegression. Die Bewertung der Ergebnisse erfolgt mit einem Jack-Knife-Vergleich für die durch Pegel beobachteten Einzugsgebiete. Zur Bestimmung von Hochwasserspenden wird für Sachsen eine Kombination aller drei Verfahren empfohlen. Die Ergebnisse sollen Planern und Wasserbehörden für die Bemessung wasserbaulicher Anlagen zur Verfügung stehen.

[Abstract]This thesis investigates a common problem of land use impacts on flood damage costs on a catchment scale. It does this through a particular case study, to quantify the technical upstream-downstream dependencies and highlights the externalities through hydroeconomicanalysis of flood damages and mitigation costs. The substantive content of the project is cross disciplinary.Peak and volume of river flows are functions of the catchment surface characteristics. This means that any impacts to the run-off regime (for example surface sealing or river training) could affect people and land users in the lower catchment. Thus, upstream activities cancause higher flood peaks, and also entail higher damages downstream. These damages are either borne by the affected parties or they are mitigated by state financed flood defence works or offset with financial compensation. These costs are usually not included in the economic considerations of the upstream land user who is partially causing them. In economic terms, these effects are referred to as unidirectional externalities. This means that a producer can export parts of his production costs to third parties and these are not included in the price of the product.The Herzogbach is a small tributary of the Danube River in Lower Bavaria. It is located in a rural area, dominated by intensive farming practices. Two villages (Bachling and Buchhofen) in the headwaters and middle section of the catchment and one city (Osterhofen) in the lowercatchment were analysed to determine the impact of upstream land use practices on the flood situation.A combination of hydrological and hydraulic modelling provided the core data to allow the interpretation of economic data, using methods of cost damage estimation. A hydrological model of the catchment provided hydrograph simulations based on (a) a regionalisation approach,(b) hydrologic flood routing and (c) hydrologic reservoir routing. A two dimensional stream flow model was then used to convert the hydrographs into flood levels, to simulatethe run-off in settled areas and determine the flood affected areas, flood levels and flow velocities. Estimates for flood damages or mitigation costs resulting from different hydrological scenarios were compared. The scenarios are based on different land uses and alloweconomic externalities to be estimated.It was found that intensive farming and river training increase the peaks, shape and volume of flood waves in comparison to extensive land use, grassland or forest. In the study area, especially river training reduced the detention effect of the river bed and the natural floodplain. These significant changes to the natural run-off regime directly affect land use in the lower catchment through flood damages and increased flood risk, and by reducing the effectiveness of planned or existing flood protection works.The thesis concludes with linked technical and economic findings which indicate a rich potential new area for research - “hydroeconomics”. The published literature shows few people have worked in this cross disciplinary area. The technical finding is that changes to land use, especially in agriculture, can increase the flood damages in downstream settlements or increase the cost of flood mitigation works significantly. From an economic point ofview, this is a unidirectional externality which should be considered in catchment and flood management. Possible solutions could include the control of land use and instruments such as separate waste water fees for rainwater and sewage or run-off certificates.

This study investigates whether the flood regime in a catchment is sensitive to the condition of riparian vegetation along the river network. The research is based on a comprehensive assessment and synthesis of field and laboratory measurements of vegetation flow resistance. A new numerical model is developed to estimate the roughness characteristics of multi-species riparian assemblages at a cross-section. Reach-scale and catchment-scale flood routing models are then applied to estimate the impact of vegetation on flood characteristics at successively larger scales. The investigation reveals that when riparian vegetation is removed at catchment-scale, peak stage declines as channel capacity increases but is also increased as the upstream catchment responds more rapidly to rain. In fact, the two competing impacts tend to cancel out leaving flood peak stage relatively insensitive to riparian condition. However, the overbank duration of a flood and flow speeds (including wave celerity) were both found to be sensitive to vegetation condition; respectively increasing and decreasing with density of vegetation. The first stage of this research examines the magnitude of the vegetation contribution to overall channel roughness, and established a means to predict it. The features of the flow resistance generated by six plant types (mature trees; grasses; aquatic plants; flexible saplings; and large woody debris) were distilled from a comprehensive review of over 160 existing publications (Chapter 2).

Masters Research - Master of Science / Recent flash floods and landslides in the Philippines have caused many fatalities, loss of livelihoods; destroyed infrastructures, damaged natural resources and displaced several communities. Investigation of five disaster cases of flash floods and landslides from 1991 to 2006 was undertaken to gain an understanding of the causes, behaviour, distribution and biophysical impacts of these recurrent natural hazards. Sustaining healthy and resilient communities and protecting the ecosystem from natural disasters is a key development goal. Therefore, communities at risk need to adequately prepare for, respond to, and recover from the impacts of these natural disasters. A theory model on community resilience called the Landslip-Disaster Quadrant Model was developed to examine the capacity for resilience and the vulnerability of threatened communities. Six building blocks comprise this Model. A community study of the February 17, 2006 landslides in St. Bernard, Southern Leyte, was conducted to test and refine this Model. Major findings of the study have revealed that flash floods and landslides have been frequent due to changing climatic patterns and greater interaction of natural processes. Extreme weather conditions have resulted in intense rainfall that seeps through fractures and cracks in the ground. Rains saturate and loosen soil particles, weaken slope resistance, triggering landslides that formed natural dams. Failure of these natural dams or log jams caused flash floods and debris flows. The rapidity and destructiveness of these hazards were influenced by the angular position of sliding materials, slope resistance, type of cascading materials caught in the flow, river channel configuration, and human structures that obstruct and/or intensify overflow. These were the physical conditions of vulnerability to disasters in the five cases of natural disaster investigated. Rural livelihoods and the economic base of the local people in Saint Bernard, Southern Leyte, were limited and subsistent. Though the local people have a high literacy rate, they have inadequate understanding of the natural processes associated with landslides. Natural observations such as receding water levels in the river, fractures and cracks in the ground on the mountain, excessive rains and landslides in nearby communities could have been used as early warnings by the local people and authorities for safe evacuation. Many lives in Guinsaugon village could have thus been saved from the deadly landslides of 17 February 2006. Political interests have affected progress of resettlement housing and development projects that obliged many local people to extend the period spent living in the evacuation centres. However, the local people were expressive of their faith and hope to rise from the tragedy. These ‘bouncing back’ attitudes of the local people were indicative of their strong cultural values that formed the core of their coping capacity for natural disasters. The results of the community study tested and refined the Landslip-Disaster Quadrant Model. Among the six blocks for building a disaster-resilient community, cultural values and local norms ranked first. This is followed by ecological security, then livelihood sufficiency and economic base, and further by human health and wellness. The last two blocks were structural networks and institutional arrangements, and political will and priorities. This Model could form the framework for a Comprehensive Landslide and Flash Flood Disaster Risk Assessment in the Philippines. The community assessment toolkit developed in this study could be expanded further into policy and planning guidelines of the National Disaster Coordinating Council of the Philippines.

The transfer of prey resources between ecosystems can have dramatic consequences for both recipient and donor systems by altering food web stability and the likelihood of trophic effects cascading across the ecosystem boundary. Landscape-scale factors influence the importance, direction and magnitude of energy flows, but may also alter the ability of consumer organisms to respond to spatio-temporal changes in allochthonous prey availability. Here, I used flood and drying disturbance gradients to investigate interactions between these two processes on populations of a riparian fishing spider Dolomedes aquaticus (Pisauridae). The abundance of aquatic insects with a winged adult stage, a major component of the diet of D. aquaticus, was markedly higher at less flood-prone rivers and declined with increasing flood disturbance. It was expected that spider populations would be largest at these stable rivers where the aquatic prey abundance was highest. However, a habitat (loose, unembedded riverbank rocks) manipulation revealed that the lack of scouring floods at these sites led to habitat-limited populations, preventing response to the increased prey resource. In fact a peak shaped relationship of spider biomass and abundance was found, with the largest spider populations at intermediately disturbed rivers. In addition, patchy habitat availability was the most likely cause of the small scale (4 m2) aggregation of spiders seen at the most stable and disturbed rivers. These patterns were also associated with strong interactions between the spiders. Stable isotope analysis of field collected spiders and an experimental manipulation of spider densities and food availability indicated that cannibalism rates were likely to be significantly higher at stable and disturbed rivers than those intermediate on the disturbance gradient. Differences in D. aquaticus population size structure and life history traits across the flood disturbance gradient were driven by interactions between resource availability, environmental stability and cannibalism rates. To separate the effects of habitat availability and aquatic prey abundance I used drying rivers, as the amount of aquatic insect prey alters as the water recedes. Desiccation mortality and low aquatic prey biomass most likely caused the spiders' spatial distribution and size class structure to alter in drying river reaches, potentially also leading to differences in cannibalism rates. Overall, cross-ecosystem transfers of prey had large impacts on the distribution, cannibalism rates and life history traits of D. aquaticus but their effects were modified by the nature of the ecosystem boundary. Thus river flow regime controlled the magnitude of the subsidy and its use by a consumer. Hence, cross-ecosystem subsidies will not always lead to larger consumer populations and consumer responses will depend on interactions between large-scale processes.

The EPID (electronic portal imaging device) was designed for in vivo imaging of patients during radiotherapy treatment. The ability of EPIDs to promptly acquire two dimensional data, lends them to be considered for use in quality assurance of the linac. This thesis set out to investigate the possibility of using a radionuclide, technetium 99 m (Tc99m), to produce a flood field for the calibration of an EPID, because using a beam calibrated EPID to measure the beam is self-referential. The difference in relative response between the energy spectrum of a 6MV beam and the Tc99m was investigated using EGSNRC DoseXYZ Monte Carlo Modelling. The relative output ratio was calculated to be less than 1.6%. The dose response of the EPID with respect to dose rate was checked using different activities of Tc99m and found to be linear. The flatness from a phantom was calculated, with a model in MATLAB, for a range of heights, overlaps, thickness, and deformations, to find the optimum balances between signal strength and flatness. This model was checked for accuracy using diagnostic radiographic film. The culmination of the energy response, linearity and the calculated flatness is a flood field taken with a flood phantom on the EPID with low signal strength. To get a signal to noise ratio of 3% the mean of over 2000 flood field images were used. This accuracy was not adequate for clinical use but the averaging of pixels it is accurate enough for QA.

Thesis (M.A.)--University of North Carolina, 1962. / Includes bibliographical references (leaves [122]-128).

Thesis (M.Eng. (Hons.)) -- University of Western Sydney, 2004. / "Masters of Engineering (Hons) thesis, University of Western Sydney, December 2004. Supervisors: Ataur Rahman and Don Carroll" Includes bibliography.