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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Living With River

Liang, Qing January 2021 (has links)
This project aims to establish a river park with purification capacity and conservation of soil and water, protecting habitats for plants and animals. Combining local history and culture to form new urban landscape and improve the urban living environment.  Historically, Yangquan had a very favorable ecological environment and was one of the birthplaces of agriculture and culture in Shanxi province. From the 1950s, after a long period of exploration, it was discovered that Yangquan had a large amount of coal resources. Since then Yangquan City has become a coal mining-oriented city. With the development of coal mining industry in recent years, the ecological environment has been deteriorated due to over-exploitation, discharge. The city's most important river, Taohe River, has suffered from declining water volume and fragile water environment, which even led to the loss of self-purification ability of the rivers.  Pollution is not the only issue with the Taohe River, but there are also floods and droughts caused by extreme weather. Therefore, river management is necessary before Yangquan transforms into a livable city. Three strategies, Optimize Water Resource, Anti-Flooding and Diverse Programs, are proposed to solve urban river issues and achieve the aim of living with river.
152

The role of groundwater in the inundation of a river-connected floodplain : case study of the river Silverån in southeast Sweden

Bång, Stina January 2019 (has links)
Fluvial flooding has long been recognized as one of the most frequently occurring natural disasters worldwide, with consequences as large economic losses from damages on infrastructure and agriculture, as well as severe impacts on human health. A less known and explored type of flooding is groundwater flooding. A flood type that for instance can arise in river-connected floodplains when groundwater levels rise to the ground surface due to increased river stages in the watercourse. Although groundwater flooding in general is a poorly understood phenomenon, it has become more recognized since its inclusion in the European Floods Directive (2007/60/EC) in 2007. Sweden has however excluded pure groundwater flooding as a separate flood type in its interpretation of the directive, but recognizes groundwater as a component which together with soil water and river water can influence the appearance of a flood event. One of the difficulties regarding groundwater floods that occur in connection to a river is that they typically are hard to differentiate from inundations of fluvial or pluvial origin. It is however important to address the role of groundwater in the inundation of these settings, since traditional flood protection strategies like levees might be circumvented by flows through the subsurface. The aim of this study has been to investigate the role of groundwater in the flooding of a river-connected floodplain by setting up a groundwater model in the integrated hydrological modeling tool MIKE SHE and couple it to an existing MIKE 11 river model, developed by DHI. The study area is a floodplain located along the river Silverån, a tributary to the river Emån, located in the south eastern part of Sweden. By running the model using four different sub-scenarios, regarding initial groundwater level and amount of precipitation, flood extent and contribution of groundwater to the inundation, in relation to other flood sources, has been investigated for different river discharges. A scenario with artificial levees constructed along parts of the river was also examined as levees have been found to have little effect on groundwater floods. As the model provides a simplified and generalized representation of reality it possesses several uncertainties, and so does the results. In summary, the results are in line with what is stated in the Swedish interpretation of the European Floods directive. It has not been possible to demonstrate pure groundwater flooding, but the results suggest that an elevated groundwater level in the beginning of a flood event will increase the extent of the inundation and result in a larger contribution of groundwater to the total amount of flood water. This suggests that there, in some cases, might be a value in integrating groundwater processes in flood risk mapping. Something that is not included in the conventional hydraulic 1D and 2D models, which traditionally are used in flood mapping. As could be expected, the results indicate that groundwater only accounts for a minor part of the flood water added to the total floodplain, while the major sources are river water and surface runoff. A delimited floodplain section that was investigated more in detail, as an increased flow from groundwater to overland water was detected along it, did however show larger contributions from groundwater. This river reach was less vulnerable to fluvial flooding, which in total resulted in a less severe flood, but also enabled a larger amount of groundwater to seep up to the floodplain surface. These conditions did also result in that the river section experienced a worsened inundation at the sub-scenario of high precipitation and high initial groundwater level, as levees were constructed along the river. Most likely because a lot of surface runoff, otherwise able to drain to the river along this section, got trapped outside the levees since it was unable to drain both to the river and to the saturated ground. These results support the theory that levees have little impact on groundwater flooding and stresses the importance 0f surveying and understanding the governing processes in the inundation of a floodplain when planning which type of flood protection scheme to use. / Översvämning utmed vattendrag, så kallad fluvial översvämning, har länge varit känd som en av de vanligast förekommande naturkatastroftyperna världen över, med konsekvenser i form av stora ekonomiska förluster, skador på infrastruktur och jordbruk samt allvarlig påverkan på människors hälsa. En mindre känd och utforskad översvämningstyp är grundvattenöversvämning. En typ av översvämning som kan uppstå i svämplanet längs ett vattendrag då grundvattennivån går upp i markytan till följd av förhöjda nivåer i vattendraget. Trots att grundvattenöversvämning generellt sett är ett outforskat fenomen har det blivit mer uppmärksammat sedan det inkluderades i det europeiska översvämningsdirektivet (2007/60/EG) som antogs 2007. I Sverige har man dock valt att exkludera renodlade grundvattenöversvämningar ur sin tolkning av direktivet och sagt att sådana inte förekommer i Sverige. Istället ser man grundvattnet som en av delarna i ett samverkande system, där det tillsammans med markvatten och ytvatten kan ha påverkan då ett vattendrag översvämmas. En svårighet med grundvattenöversvämningar som inträffar i anslutning till vattendrag är att de kan vara svåra att skilja från översvämningar med fluvialt eller pluvialt ursprung. Det är dock viktigt att uppmärksamma grundvattnets roll i den här typen av översvämningar då traditionella åtgärder som sätts in mot översvämningar, såsom invallningar, kan kringgås av flöden genom marken. Syftet med den här studien har varit att undersöka grundvattnets roll vid en översvämning utmed ett vattendrag genom att konstruera en grundvattenmodell i det integrerade hydrologiska modellverktyget MIKE SHE och koppla denna till en befintlig MIKE 11 vattendragsmodell, utvecklad av DHI. Modellområdet som studerats är beläget längs Silverån, ett av biflödena till Emån i sydöstra Sverige. Genom att undersöka fyra olika delscenarion, avseende initial grundvattenyta och nederbördsmängd, har översvämningsutbredning samt grundvattnets bidrag till översvämningen utvärderats för olika vattenflöden. Ett scenario där invallningar konstruerats längs delar av vattendraget har också undersökts, eftersom invallningar visat sig ha begränsad effekt på grundvattenöversvämningar. Eftersom modellen utgör en förenklad och generaliserad representation av verkligheten har den flertalet osäkerheter, något som även gäller för modellresultaten. Sammanfattningsvis kan sägas att resultaten är i linje med den svenska tolkningen av det europeiska översvämningsdirektivet. Det har inte varit möjligt att påvisa renodlade grundvattenöversvämningar. Däremot pekar resultaten på att en förhöjd grundvattennivå under inledningen av ett översvämningstillfälle kommer att bidra till en ökad översvämningsutbredning, samt ett större bidrag av grundvatten till den totala mängden översvämningsvatten. Detta indikerar att det i vissa fall skulle kunna finnas en mening i att inkludera grundvattenprocesser vid översvämningskartering. Något som inte finns med i de konventionella hydrauliska 1D- och 2D-modeller som traditionellt används vid översvämningskarteringen. Som väntat visar resultaten på att grundvattnet står för en mycket liten del av det vatten som totalt översvämmar det undersökta svämplanet, och att de främsta källorna är vatten från vattendraget tillsammans med ytavrinning. Längs en avgränsad sträcka av svämplanet som undersöktes mer i detalj, då ett ökat flöde från grundvatten till vatten på markytan påträffades längs denna, återfanns dock ett större bidrag från grundvattnet. Denna del av svämplanet var mindre känsligt för fluvial översvämning, något som på det hela taget resulterade i en mindre allvarlig översvämning, men också tillät en större mängd grundvatten att tränga upp på markytan. Dessa förhållanden ledda också till att den aktuella delen av svämplanet kom att få en förvärrad översvämning då vallar konstruerades för delscenariot med hög nederbörd och initialt hög grundvattenyta. Detta till följd av att en stor mängd ytavrinning, som tidigare kunnat dräneras till den här delen av vattendraget, fastnade utanför vallarna istället för att avledas till vattendraget eller infiltrera den mättade marken. Dessa resultat kan sägas stödja teorin kring att invallningar har liten påverkan på grundvattenöversvämningar och visar på vikten av att undersöka och förstå styrande processer kring översvämningen av ett svämplan då åtgärder mot översvämning planeras.
153

Modeling Flood Reduction Scenarios for a Small Coastal Community

Perez, Evan J. 01 March 2013 (has links) (PDF)
The Arroyo Grande Creek Watershed, an approximately 170 mi2 watershed located on the central coast of California, drains to the Pacific Ocean via the Arroyo Grande Creek that passes through several coastal cities including the community of Oceano. At the mouth of the Creek is the Arroyo Grande Lagoon, which is connected to another lagoon known as the Oceano Lagoon, by a tidal flap-gate whose hydraulics is a function of water levels in the two lagoons. Historically the Oceano Lagoon has played a part in floods that have occurred in the community of Oceano. The most recent flooding occurred in 2010 when a storm with about a10-yr frequency caused flooding that led to an estimated property damage of about two million dollars. This study was conducted to understand hydrology of the Arroyo Grande watershed that also feeds Lopez Lake, a reservoir that provides water for drinking, agriculture, and environmental flows; to characterize hydraulics of the Oceano Lagoon; and to explore scenarios for flood mitigation. Objectives of the study are to provide a better understanding of the causes of the historical floodings; map the extent of floodings for various storm events including 10 year, 50 year, and 100 year under current conditions; and examine potential solutions to reduce future floodings. Surface water hydrology of the Arroyo Grande Creek Watershed was studied using HEC-HMS to quantify runoff specifically into the Oceano Lagoon. HEC-HMS was calibrated using known streamflow to improve the accuracy of the model. The HEC-HMS model was developed using spatial data that was organized in ArcMAP. Data such as elevation, land use, soil type, and impervious surface were processed using HEC-GeoHMS and exported to HEC-HMS. Mitigation measures were simulated in HEC-HMS by adjusting parameters such as the outlet configuration and the increased volume in Oceano Lagoon. Each mitigation measure delivered varying effectiveness. Results show that while the peak flow and volume in the lagoon can be reduced, larger design storms will continue to inundate the area unless drastic steps are taken. The findings could assist local flood control agencies by evaluating the risks of continuing to use the existing drainage system, and identifying opportunities available to reduce those risks.
154

Framework for better Routing Assistance for Road Users exposed to Flooding in a Connected Vehicle Environment

Hannoun, Gaby Joe 01 November 2017 (has links)
Flooding can severely disrupt transportation systems. When safety measures are limited to road closures, vehicles affected by the flooding have an origin, destination, or path segment that is closed or soon-to-be flooded during the trip's duration. This thesis introduces a framework to provide routing assistance and trip cancellation recommendations to affected vehicles. The framework relies on the connected vehicle environment for real-time link performance measures and flood data and evaluates the trip of the vehicle to determine whether it is affected by the flood or not. If the vehicle is affected and can still leave its origin, the framework generates the corresponding routing assistance in the form of hyperpath(s) or set of alternative paths. On the other hand, a vehicle with a closed origin receives a warning to wait at origin, while a vehicle with an affected destination is assigned to a new safe one. This framework is tested on two transportation networks. The evaluation of the framework's scalability to different network sizes and the sensitivity of the results to various flood characteristics, policy-related variables and other dependencies are performed using simulated vehicle data and hypothetical flood scenarios. The computation times depends on the network size and flood depth but have generally an average of 1.47 seconds for the largest tested network and deepest tested flood. The framework has the potential to alleviate the impacts and inconveniences associated with flooding. / Master of Science
155

The role of roads on hydrological response : Modeling and assessment for Swedish watersheds

Nickman, Alireza January 2014 (has links)
Understanding the role of road networks in alteration of hydrological responses is crucial for maintaining the accessibility and durability of road infrastructures. Road construction is one of the most common man made disturbances to a landscape. However, still the quantitative role of road topographical and geo-morphological properties on the hydrological response of storms in catchments is only partially understood. The aim of this study was to use new methods to estimate and quantify the flood hazard probability with reference to the most influential physical catchment descriptors and road characteristics. In addition physical based modelling was used to estimate the effect of road topography on the hydrological responses of watersheds to storms with different intensities. A simple method was developed and discussed to address the most susceptible locations to flooding along the roads. Multivariate statistical analysis (PLS) employed to quantify the flood risk probability in the road-stream crossings concerning the correlation between the quantities of the physical catchment descriptors and occurrence/absence of flooding. The most influential factors in describing the probability of flooding along the roads were topographic wetness index, soil properties, road density and channel slopes. A detailed study of simulated flow duration curves showed differences between 20 watersheds for three different storms based on a digital elevation data with and without roads. An increase in peak flow and reduced delay occurred with increased storm intensity. However, the impact of the roads was much smaller and only possible to identify by detailed examination of statistical descriptors. / <p>QC 20140214</p>
156

Timescales of Global Tidal Flooding

Bower, Maria 01 January 2019 (has links)
Millions of people in low-lying areas are already affected by flooding, and the number will increase substantially in the future. Tidal flooding, the form of flooding caused by a combination of high tides and sea level rise to overcome protection levels, can cause damage and inconveniences such as road closures, overwhelmed drainage systems, and infrastructure deterioration from water damage. Tidal flooding already occurs annually in cities along the U.S. east coast, most notably Miami. However, the time it will take for other regions globally to begin to experience tidal flooding has not yet been assessed. Therefore, there is a limited understanding of how and when human populations will be exposed to this type of flooding. Tide gauge data from the GESLA-2 data base are used to obtain information about the highest astronomical tide (HAT) and extreme value statistics for 571 locations globally. For a complete spatial analysis, modelled water levels from the Global Tide and Surge Reanalysis (GTSR) are also used. Estimated protection levels are extracted from the DIVA database and translated to absolute heights based on the extreme value statistics of high water levels. This analysis is based on calculating the difference between the existing protection level and HAT, which indicates how much sea levels can rise before tidal flooding occurs, and evaluating in what decade this is expected to happen under different sea-level rise (SLR) scenarios. Tidal trends from the nodal and perigean are also taken account and used to modify 1000 different sea level rise scenarios to provide a more comprehensive analysis of possible tidal flooding years. Our results indicate that tidal flooding may occur within a few decades in many locations (under the assumption that no adaptation will take place), and therefore awareness should be heightened so that actions can be taken to minimize the impacts.
157

Characterizing flooding regimes in the lower Mississippi Alluvial Valley over recent two decades

Zhou, Xichun 06 August 2021 (has links)
The Lower Mississippi Alluvial Valley (LMAV) was once the largest floodplain in the United States. Flooding regimes in the LMAV have strong impacts on the soil biogeochemical processes, nutrient cycling, forest species distribution, agricultural production, and wildlife habitat. This study characterized the LMAV flooding regimes using the 8-day-composite Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance product from 2001 - 2018. The results showed significant spatial variations in the annual flooding duration in the LMAV, and the flooding area showed remarkable seasonal variations in the northern and central LMAV with the peak flooding area in winter and early spring. Digital Elevation Model (DEM) and slope were identified as the two major factors in determining the spatial pattern of flooding regimes. The LMAV flooding regimes dataset provides a scientific basis for the governments to design forest, agriculture, and wildlife management policies to enhance ecosystem services. Landowners also can use this information to make decisions for cropland retirement and tree plantation.
158

Before the Deluge

Sodo, Mark 01 September 2015 (has links)
No description available.
159

Collective Potential: A Network of Acupuncture Interventions for Flood Resiliency

Wickramanayaka, Sachini H. K. 28 September 2018 (has links)
No description available.
160

People’s Perception of Channelization of the Hocking River, Southeastern Ohio

Gómez Pezzotti, Fausto January 2005 (has links)
No description available.

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