<p>Mosquitoes are found in extremely large numbers in the lower parts of the River Dalälven. In the year 2000 the mosquito nuisance was especially high, resulting in foundation of the Biological mosquito control project. Since 2001 mosquito larvae are controlled by using a biological pesticide BTI (Bacillus thuringiensis ssp israelensis). The mosquito fauna in the area is dominated by flood water mosquitoes, a group of mosquitoes that are very aggressive and form new generations of mosquitoes during every single flooding event during the summer. To be able to efficiently control the mosquitoes it is essential to know the extension and locality of the flooding. A flooding event is evaluated by how high the water level will reach and at which time the top of the hydrograph is accruing. There is a need for a tool for short time prediction of flooding events in the Nedre Dalälven region. In this study a hydraulic model in the software HEC-RAS has been used, here called HEC-RAS NEDA. The hydraulic model came up with good results when predicting water surface levels. The validation process made from figures of a period with large amplitude in water levels showed that the modelled water level was within ± 0,05 m from the observed water stands. It is a stable model that can handle 100-year flows with quick changes in the flow. The correspondence is good concerning the water levels and it functions well when studying the top of the hydrograph. HEC-RAS NEDA is an accurate and easy to manage tool for prediction of flooding in the lake of Bysjön, Österviken and Färnebofjärden. Modelled results have been compared with the model made by Swedish meteorological and hydrological institute on the request of Räddningsverket. The results from the two models shows large discrepancies, probably because of low accuracy data entered into the model from Räddningsverket. Räddningsverket has used the Geographical Sweden Data height data bank´and I used the height data from a laser scanned digital terrain model. Area studies have also been made according to how the area of the water surface changes with the water stand. These studies show that during the flood in year 2000, 55 km2 was flooded based on laserscanning in Färnebofjärden.</p> / <p>Mygg förekommer i extremt stora antal i området kring nedre delen av Dalälven. År 2000 var myggplågan särskilt stor vilket medförde att projekt Biologisk Myggkontroll bildades. Myggbekämpning har bedrivits i Nedre Dalälven sedan 2001 med ett biologiskt bekämpningsmedel, Bacillus thuringiensis ssp israelensis (BTI). Områdets myggfauna domineras av så kallade översvämningsmygg, en grupp stickmyggor som är mycket aggressiva och bildar nya generationer efter varje enskild översvämning under sommaren. För en effektiv bekämpning av mygglarverna krävs att man vet översvämningens omfattning och lokalisering. En översvämning bedöms med avseende på hur högt vattenståndet når samt vid vilken tidpunkt hydrografens toppvärde inträffar. Det finns ett behov av ett verktyg som kan utföra korttidsprognoser av översvämningar i Nedre Dalälven. I denna studie har en hydraulisk modell i programvaran HEC-RAS använts, här kallad för HEC-RAS NEDA. Den hydrauliska modellen fungerar bra till att användas för prediktering av vattenstånd i Nedre Dalälven. Valideringen av modellen mot värden under en testperiod med stor amplitud i vattenståndet visade att modellerade vattenstånd var inom ± 0,05 m från de uppmätta värdena. Modellen är stabil och klarar av att hantera 100-årsflöden med snabba flödesfluktuationer. HEC-RAS NEDA är ett noggrant och lätthanterligt predikteringsverktyg för översvämningar i Bysjön, Österviken och Färnebofjärden. Överensstämmelsen är god gällande nivån av vattenståndet och den fungerar bra för att studera hydrografens topp temporärt. Modellerade resultat har jämförts med karteringar som Sveriges meteorologiska och hydrologiska institut har gjort på Räddningsverkets begäran. Resultaten skiljer sig betydligt mellan HEC-RAS NEDA och Räddningsverkets modell, troligen på grund av att Räddningsverket har stora svagheter i indata till modellen. Räddningsverket har använt Geografiska Sverige Data-Höjddata och modellen HEC-RAS NEDA är framtagen med höjddata från en digital terrängmodell baserad på laserscanning. Areella studier i GIS över hur arean av vattenspegeln förändras med vattenståndet visar att Färnebofjärden under augusti år 2000 lade 55 km2 under vatten.</p>

Thesis (MPH.) -- University of Limpopo, 2015 / Introduction: A qualitative study was undertaken to assess the impact that flooding of the Okavango river have on the health of the community of Sepopa village. Aim: To assess the impact that flooding of the Okavango River has on the health of the community of Sepopa village. Study: the study was conducted in the village of Sepopa within the community aged between fifteen years and above. The village has an estimated population of 2824. Method: A non experimental descriptive research design using qualitative approach was used. Sampling: Two types of sampling procedure were used, being simple random sampling and purposive sampling. Results: The study revealed that 85% of the respondents reported or suffered from the injuries due to high waters brought about by floods, 92% reported to have fallen sick or having a member of their family who was sick with conditions related to floods. Of all the respondents, 54% explained they heard of deaths occurring in a river either due to drowning or crocodile and hippopotamus attacks. Lastly, 8% of respondents reported they never heard of any injuries, illness or death due to the impacts of floods. Conclusion: It can thus be concluded that the river has an impact to the health of the community either before, during and after a flood event, activities may be undertaken by the population at risk, by policy makers and by emergency responders to reduce health risks. Proper planning aimed to reduce the harmful effects of flooding by limiting the impact of a flood on human health and economic infrastructure should be adopted. Key words: health, sepopa village, impact, Okavango river.

Many attempts have been made to control water conformance. It is very costly to produce, treat and dispose of water, and produced water represents the largest waste stream associated with oil and gas production. The production of large amounts of water results in: (a) the need for more complex water?oil separation; (b) corrosion of wellbore and other equipment; (c) a rapid decline in hydrocarbon production rate and ultimate recovery; and (d) consequently, premature abandonment of a well or field, leaving considerable hydrocarbons unproduced. Sometimes water production results from heterogeneities in the horizontal direction, which leads to uneven movement of the flood front and subsequent early breakthrough of water from high permeability layers. This problem is exacerbated if there is (vertical) hydraulic communication between layers so that crossflow can occur. One of the novel technologies in chemical enhanced oil recovery (EOR) is a gel type called deep diverting gel (DDG), which describes material that functions by plugging thief zones deep from the well where they were being injected. To evaluate the performance of this new treatment method, we will (1) model the treatment methods, (2) conduct economic analysis, and (3) compare different EOR methods. We have conducted relevant literature review about the development, design, modeling and economics of the enhanced oil recovery methods. Schlumberger's Eclipse simulator software has been used for modeling purposes. Modeling runs have demonstrated that placement of a DDG in a high permeability zone provided a blockage that diverted water into lower permeability areas, thus increasing the sweep of target zones. Research results demonstrated that, although higher recovery can be achieved with a polymer flood, the combination of delayed production response and large polymer amounts cause such projects to be less economically favorable than deep gel placement treatments. From results of several sensitivity runs, it can be concluded that plug size and oil viscosity are two determining factors in the efficiency of DDG treatments. For the assumed case, economic analysis demonstrated that DDG has the most positive net present value (NPV), with polymer flooding second and simply continuing the waterflood to its economic limit the least positive NPV.

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Although the global energy demand is shifting towards a well-balanced energy mix, fossil fuels will continue to have a significant role in this transition and will maintain a big share in the energy mix portfolio. The production of oil and gas has already reached the apex in the time that most of the conventional giant reservoirs are depleting, and discoveries for new reserves have shrunk down. In conventional reservoirs, it is estimated that about two-thirds of the Original Oil in Place (OOIP) will not be produced within the field lifecycle, corresponding to an average Recovery Factor (RF) between 20% and 40%. This low recovery factors from traditional methods trigger more investments in the Enhanced Oil Recovery (EOR) techniques. Waterflooding is one of the most commonly used technique to increase RF by raising or maintaining reservoir pressure. Lack of comprehending the driving forces in Naturally Fractured Reservoirs and reservoir heterogeneity may lead to serious conformance problems in which dealing with excessive undesirable water production becomes very challenging. Chemical EOR through an injection of a polymer solution is amongst the tested options that can be used to improve sweep efficiency. Ultimately, understanding the reservoir characteristics and having the know-how to implement the best recovery option will help to maximize the field’s lifecycle and increase the RF. Therefore, this study investigates some key elements that have a significant influence on the overall fluid flow behavior. The work reveals insights on the impact of capillarity and wettability in heterogeneous porous media. An experimental lab-scale consisting of a 2D sandbox model, which mimics a water-wet fractured system with injection and production ports, was designed, fabricated, and tested in single-phase and two-phase flow scenarios including the injection of water and polymer solutions. In the case of single-phase flow, a waterflood baseline scenario was studied with controlled variables, which helped to distinguish the contrast with the polymer flood case. Implementing water injection in a fractured water-wet reservoir showed that water prefers to channel through high permeable streaks, which consequently leads to poor volumetric sweep leading to significant bypassed zones. Investigating the two-phase flow was the essence of this research. Thus, the same procedures were repeated where water and polymer were used to displace oil. During waterflooding, due to strong capillarity contrast between the matrix and fracture media, flow divergence was found to be faster towards the matrix medium where the matrix gets saturated faster than that the fracture, overriding the high permeability of the fracture. Whereas, polymer flooding exhibited better volumetric sweep in all scenarios. Numerical simulations were used to replicate the experiments. This work can give new visual insights about key recovery mechanisms in heterogeneous reservoirs using polymers.

Amazonian tropical forests account for 20-50% of global primary productivity and up to 40% of carbon stored in terrestrial biomass (Phillips et al., 1998). The Amazon is also home to the Earth’s largest river system, accounting for approximately 20% of the world’s total river discharge (Richey et al., 1989). Despite the clear global significance of the Amazon basin, substantial uncertainties remain in terms of both aboveground wood biomass and carbon storage within its extensive forests (Houghton et al., 2001), and the functioning of its river systems, particularly in terms of floodplain inundation (Wilson et al., 2007). This thesis addresses the aforementioned uncertainties through providing new insight into the interaction between fluvial processes and Amazonian floodplain varzea forests, for the Beni floodplain in north east Bolivia. Flood inundation dynamics for the Beni floodplain are quantified through application of a 1D-2D hydraulic model code, with topographical forcing provided through bare earth DEMs derived from the SRTM global elevation dataset (Farr and Kobrick, 2000). Subsequently, in the final part of the thesis, aboveground wood biomass estimates are generated for the Beni floodplain, through extrapolation of plot scale inventory measurements with respect to spatially distributed remote sensing datasets. These estimates are subsequently integrated with modelled flood inundation and maps depicting Beni river channel migration, in order to explore the influence which fluvial processes exert upon aboveground wood biomass storage in varzea forest stands. Overall, results presented within this thesis quantitatively demonstrate that fluvial processes, specifically flood inundation and lateral channel migration, exert significant impacts upon aboveground biomass storage within Beni floodplain forests. Furthermore, as a result of these influences, aboveground wood biomass storage within Beni floodplain forests is substantially lower than would be expected based upon published estimates for varzea forests across the Amazon (Baker et al., 2004; Saatchi et al., 2007). This implies that systematic overestimation of aboveground wood biomass storage for Amazonian varzea forests may constitute a significant source of uncertainty in basin scale biomass estimates.

Detta arbete syftar till att undersöka hur blå-grön infrastruktur kan användas som en metod för översvämningsskydd vid hamnomvandlingar av industriområden som en del i att öka städers resilience. Forskningsdesignen som används är en fallstudie av fenomenen blå-grön infrastruktur och urban flooding. Arbetets teoretiska ramverk utgörs av non-equilibrium-paradigmets syn på begreppet resilience. Resilience definieras här som ett system som påverkas av externa och interna processer samtidigt som det har en förmåga till kontinuerlig anpassning samt en fortlöpande funktionalitet. Av arbetets analys framkommer att vid implementering av blå-grön infrastruktur är helheten större än summan av delarna. Det är därför centralt att alla delar av det blå-gröna infrastruktursystemet fyller en funktion i sig själva så väl som i förhållande till varandra. Detta är den viktigaste aspekten som måste uppfyllas om blå-grön infrastruktur ska kunna möta de krav som urban flooding och havsnära exploatering ställer. / This studie aim to investegate how blue-green infrastructure can be used as a method for urban flood-prevention in redevelopments of former harbors as a part of increasing the resilience capacity of urban areas. The method is a case study of the fenomenon blu-green infrastructure and urban flooding. The studies theoretical framework is the non-equilibrium paradigm view of resilience. In this studie resilience is viewed as a system that is influenced by internal and external processes as well as retaining the capacity of constant adaptation and functionality.  As a result of the studies analysis it is shown that when implementing blue-green infrastructure the idea of that the whole is bigger than total of the parts is vital. The system that aims to cope with urban flooding has to be functional as a cohesive system as well as in the separate parts. This is the most important idea if blu-green infrastructure is to be useful in coping with the consequences of urban flooding as well as ensuring a more resilient future.

Deltastream is an on-going project carried by Tidal Energy Limited since almost twenty years. It is a tidal energy converter with a triangular shape and one turbine on each tower. It has gone through many evolutions of design but a first prototype will be installed in the end of 2014 at Ramsey Sound. The deployment and recovery operations will be carried out with a single lift point through a heavy lift frame. Two issues have to be tackled during the operation: the rate of flooding of the ballasts and the tension on the lift crane cable. The most favourable sea state must be found in order to minimise the crane cable tension as well as the best inlets and outlets configuration for the ballasts system. In order to tackle those issues, preliminary analytical work was conducted on the demonstrator to assess the stability during the flooding process. A scaled model was designed and built in order to be tested in a wave-towing tank. The results from the tests highlight that the deployment and the recovery operations are safe for both the barge and Deltastream for the range of wave conditions tested in the tank. However, the sea state has an important impact on the proceeding of the operations, especially the period of the waves.

With the depletion of oil reserves and increase in oil price, the enhanced oil recovery methods such as polymer flooding to increase oil production from water flooded fields are becoming more attractive. Effective design of these processes is challenging because the polymer chemistry has a strong effect on reaction and fluid rheology, which in turn has a strong effect on fluid transport. We have implemented a well-established polymer model within the Implicit Parallel Accurate Reservoir Simulator (IPARS), which enables parallel simulation of non-Newtonian fluid flow through porous media. The following properties of polymer solution are modeled in this work: 1) polymer adsorption; 2) polymer viscosity as a function of salinity, hardness, polymer concentration, and shear rate; 3) permeability reduction; 4) inaccessible pore volume. IPARS enables field-scale polymer flooding simulation with its parallel computation capability. In this thesis, several numerical examples are presented. The result of polymer module is verified by UTCHEM, a three-dimensional chemical flood simulator developed at the University of Texas at Austin. The parallel capability is also tested. The influence of different shear rate calculations is investigated in homogeneous and heterogeneous reservoirs. We observed that the wellbore velocity calculation instead of Darcy velocity reduces the grid effect for coarse mesh. We noted that the injection bottom hole pressure is very sensitive to the shear rate calculation. However, cumulative oil recovery and overall oil saturation appear to not be sensitive to grid and shear rate calculation for same reservoir. There are two models to model the ground water infiltration in vadose zone. One is Richard’s Equation (RE) model. And the other is two-phase flow model. In this work, we compare the two-phase model with an RE model to ascertain, under common scenarios such as infiltration or injection of water into initially dry soils, the similarities and differences in solutions behaviors, the ability of each model to simulate such infiltration processes under realistic scenarios, and to investigate the numerical efficiencies and difficulties which arise in these models. Six different data sets were assembled as benchmark infiltration problems in the unsaturated zone. The comparison shows that two-phase model holds for general porous media and is not limited by several assumptions that must be made for the RE formulation, while RE is applicable only for shallow regions (vadose) that are only several meters in depth and a fully saturated bottom boundary condition must be assumed. / text

Master of Arts / Department of Geography / John A. Harrington Jr / Wildcat Creek Watershed near Manhattan, Kansas, experiences damaging flash floods that have required evacuations in recent years (Spicer 2011). The purpose of this study was to qualitatively examine the issue of flooding in the Wildcat Creek Watershed through interviewing stakeholders (those that reside, own a business, or study) using a semi – structured approach. Interview discussion examined stakeholders’ perceptions of 1) how they understand the processes that create the flooding hazard, 2) whether or not they value the implementation of mitigation efforts to reduce the negative impacts of flooding, 3) whether they feel at risk to flooding, and 4) who they consider a trusted source of information about the hydrologic characteristics of the watershed. Based on the results of this study, a spatial relationship in perceptions of flooding issues in the Wildcat Creek Watershed was found. Across the study area, stakeholders understood many of the physical causes of flooding, but did not tend to see the connections among the many physical components. Overall, stakeholders believed that mitigation strategies to curb flash flooding were valuable, although many were not supportive of paying for these efforts through potential taxation from a watershed district. Despite the increase of flooding events in the past decade (Anderson 2011), many stakeholders neither saw any changes in their personal risk of exposure to flooding nor a change in their flood vulnerability. In the context of the flooding issue in Wildcat Creek Watershed, most participants trusted their neighbors and community leaders as sources of information instead of professionals who research and/or conduct work on the watershed.