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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.
311

A study of flash flood potential in western Nevada and eastern California to enhance flash flood forecasting and awareness

Brong, Brian S. January 2005 (has links)
Thesis (M.S.)--University of Nevada, Reno, 2005. / "December 2005." Includes bibliographical references (leaves 77-78). Online version available on the World Wide Web.
312

Water Storage Capacity and Flow Dynamics in a Papyrus Wetland, Uganda : Implications for Studies of Water Treatment Effects

Asp, Karl January 2009 (has links)
<p><!--[if !mso]> <object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object><mce:style><! st1\:*{behavior:url(#ieooui) } --></p><p>Hydrological investigations were performed in the Lubigi papyrus wetland in suburban Kampala, Uganda, impacted by human encroachment for settlement and agriculture. The first aim was to investigate the water flow variations and the dampening effect of the wetland. A second aim was to estimate the effective wetland volume and area, and relate this to the wetland function for treatment of the suburban runoff. A study site with well defined inflows and outflows was chosen, and three transects were cut through the papyrus to be able to study the water movement beneath the floating papyrus mat. Water flow measurements showed a flow dampening effect of the wetland on peak flows after rains, and the water balance revealed that the precipitation on the wetland was only 4 % of the inflow during the study. The tracer added at the inlet was rapidly detected downstream in the canal in the middle of the wetland, indicating a strong short-circuiting effect of the human made canal. At the outlet the tracer concentration was lower than the detection limit, suggesting a good mixing in the downstream part of the wetland, which was also supported by other water quality measurements in the transects. Ammonium-N concentrations at the inflow and outflow indicated a net export of ammonium-N, but the observed flow variations suggest that intensive water sampling campaigns are necessary for a proper evaluation of the water treatment function. The calculated effective volume and area amounted to 74 and 46 %, respectively, of the theoretically estimated, with a corresponding loss in the flow dampening and water treatment function of the wetland.</p><p> </p> / Rapporten är ett resultat av ett Minor Field Study stipendium finansierad av Sida.
313

Patterns of River Breakup Timing and Sequencing, Hay River, NWT

Kovachis, Nadia 06 1900 (has links)
River ice breakup and associated flooding are realities for many northern communities. This is certainly the case in Hay River, NWT, which is located at the junction of the Hay River and Great Slave Lake. Hay River experiences a wide range of spring river ice scenarios; from docile thermal melt outs, to severe ice jams resulting in life-threatening, disastrous flooding. This study involved the analysis of five seasons of aerial and time-lapse photographs, water level measurements and hydrometeorologic data. This work also compiled an extended historical record of breakup in the Hay River delta, which was compared against the field data gathered for this study; combining local, experiential knowledge with scientific observation into a cohesive description of breakup. This will be used to advise the non-technical flood watch community on the patterns of timing and sequencing of breakup, which is critical for evacuation planning. / Water Resources Engineering
314

Predictability of hydrologic response at the plot and catchment scales: Role of initial conditions

Zehe, Erwin, Blöschl, Günter January 2004 (has links)
This paper examines the effect of uncertain initial soil moisture on hydrologic response at the plot scale (1 m2) and the catchment scale (3.6 km2) in the presence of threshold transitions between matrix and preferential flow. We adopt the concepts of microstates and macrostates from statistical mechanics. The microstates are the detailed patterns of initial soil moisture that are inherently unknown, while the macrostates are specified by the statistical distributions of initial soil moisture that can be derived from the measurements typically available in field experiments. We use a physically based model and ensure that it closely represents the processes in the Weiherbach catchment, Germany. We then use the model to generate hydrologic response to hypothetical irrigation events and rainfall events for multiple realizations of initial soil moisture microstates that are all consistent with the same macrostate. As the measures of uncertainty at the plot scale we use the coefficient of variation and the scaled range of simulated vertical bromide transport distances between realizations. At the catchment scale we use similar statistics derived from simulated flood peak discharges. The simulations indicate that at both scales the predictability depends on the average initial soil moisture state and is at a minimum around the soil moisture value where the transition from matrix to macropore flow occurs. The predictability increases with rainfall intensity. The predictability increases with scale with maximum absolute errors of 90 and 32% at the plot scale and the catchment scale, respectively. It is argued that even if we assume perfect knowledge on the processes, the level of detail with which one can measure the initial conditions along with the nonlinearity of the system will set limits to the repeatability of experiments and limits to the predictability of models at the plot and catchment scales.
315

Feasibility research of sewage disposal planning of initial stage of Stormwater of community's drainage system

Kuo, Chin-Ching 27 July 2007 (has links)
This research is based on the plan and design of Datang constructed wetland as a storm water wetland system. Qantity of the discharges from Datan community drainage system including its branches surround Dapeng Bay National Scenic Area are estimated. The objectives of this research is to study the possibilities of using the concept of stormwater wetland system for including the Datan constructed wetland and Lin-Bian right-bank wetland as flood detention wetland system and treatment wetlands during the dry season. Generally, flood detention ponds are not functioning except during storm seasons. Rainfall are mostly concentrated from June to September in southern Taiwan (mainly due to southwest monsoon and typhoon), the Datan wetland has therefore planned to treat the domestic sewages and the disposal from aquaculture farms during the dry season, and first flushing drainage during storm season. Besides the flood detention volume, Datan wetland has been designed into four major sections, a) primary settling for settle part of the suspended particles and aeration; b) bio-filtration through 2 sets of bio-filter using crushed bricks and oyster shells as filter media, mainly designed for BOD removal and partly early denitrification; c) followed by shallow weeds pond for reaeration and nutrients uptake by plantation; d) entering a series of open water ponds for stabilization. Landscape has been take good care for recreative function and habitat reserved for variety of birds. Due to the flood detention function will flood the basin few times a year, variable depth environment and plantations are designed. Wetland maintains ordinary water level at EL=-1.1m, maximum flood detention can go as high as EL=+1.5m. The wetland has effective surface approximately 5.5 ha., maximum flood detention quantity approximately 130,000 cubic meters. Since the area is tidally affected, influents contain different levels of salinities. Plantation becomes a difficult issue for the Datan wetland, due to the saline waters. Mangrove is the best choice, so far, for this situation. The mangrove forest has the richest productivity on wetland ecosystem, and can carry on the physical biology multistage degeneration to the sewage and absorb various pollutants. Hydraulic analysis estimates the peak discharge of Datan drainage system¡¦s 10 year flood frequency is 20.17cms, Datan constructed wetland and Linbian right bank constructed wetland can reduces the peak rate of 8.06cms and 4.38 cms, respectively. In addition, most of the branches of the Datan drainage system are thus achieve the ten year return period bench mark from the HEC-RAS evaluation The water quality monitoring results after one month of operation have shown the average elimination rates, TOC=-10%, BOD5=53%, TKN=71%, NH3-N=88%, NO3-N=65, NO2-N=90%, TN=70%, TP=52%, OP=56%, Chl.a=-61%, SS=4%, the turbidity (NTU)=70%. BOD and nutrients are shown effective reductions, while the SS and the chlorophyll-a are correlated mainly due to the plankton growth in the open waters. Long-term monitoring is continuing for the evaluation of the water quality purification function and the operational management model.
316

Analyses Of Flood Events Using Regional Hydrometeorological Modeling System

Onen, Alper 01 January 2013 (has links) (PDF)
Extreme rainfall events and consequent floods are being observed more frequently in the Western Black Sea region in Turkey as climate changes. In this study, application of a flood early warning system is intended by using and calibrating a combined model system. A regional-scale hydro-meteorological model system, consisting of Weather Research and Forecasting (WRF) model, NOAH land surface model and fully distributed NOAH-Hydro hydrologic models, is used for simulations of 25 heavy-rainfall and major flooding events observed in the Western Black Sea region between years 2000 and 2011. The performance of WRF model system in simulating precipitation is tested with 3-dimensional variational (3DVAR) data assimilation scheme. WRF-derived precipitation with and without data assimilation and Multi Precipitation Estimates (MPE) are used in NOAH-Hydro model to simulate streamflow for flood events. Statistical precipitation analyses show that WRF model with 3DVAR improved precipitation up to 12% with respect to no-assimilation. MPE algorithm generally underestimates rainfall and it also showed lower performance than WRF model with and without data assimilation. Depending on reliability of precipitation inputs, NOAH-Hydro model produces reasonable flood hydrographs both in structure and volume. After model calibration is performed using assimilated precipitation inputs in Bartin Basin, NOAH-Hydro model reduced the average error in streamflow by 23.24% and 53.57% with calibration for testing events. With calibrated parameters, NOAH-Hydro model forced by WRF non-assimilated precipitation input also reduced the error in streamflow but with lower rates (16.67% and 40.72%). With a proper model calibration and reliable precipitation inputs, hydrologic modeling system is capable of simulating flood events.
317

Citizen participation in post-disaster flood hazard mitigation planning: Exploring strategic choices in Peterborough, Ontario

Oulahen, Gregory Stephen January 2008 (has links)
This thesis explores the role of citizen participation in a post-disaster flood hazard mitigation planning program in Peterborough, Ontario. Recognizing that citizen participation is an integral element of hazards mitigation planning, a review of the relevant literature identifies six strategic planning choices that should be considered in the design of a citizen participation program. The study applies this framework to the Flood Reduction Master Plan (FRMP) study and planning process in Peterborough, undertaken following the July 2004 flood event, to analyze citizen participation in hazard mitigation planning practice. Existing documentation, including the FRMP, and fifteen key informant interviews provided the main sources of research data. Data were analyzed in terms of the framework and other hazards mitigation theory found in the literature to produce the findings of the study. There existed many strengths and several weaknesses of the citizen participation aspect of the planning program. Many of the decisions made regarding citizen participation in the FRMP process can be considered successful by the standards set in the literature.
318

Citizen participation in post-disaster flood hazard mitigation planning: Exploring strategic choices in Peterborough, Ontario

Oulahen, Gregory Stephen January 2008 (has links)
This thesis explores the role of citizen participation in a post-disaster flood hazard mitigation planning program in Peterborough, Ontario. Recognizing that citizen participation is an integral element of hazards mitigation planning, a review of the relevant literature identifies six strategic planning choices that should be considered in the design of a citizen participation program. The study applies this framework to the Flood Reduction Master Plan (FRMP) study and planning process in Peterborough, undertaken following the July 2004 flood event, to analyze citizen participation in hazard mitigation planning practice. Existing documentation, including the FRMP, and fifteen key informant interviews provided the main sources of research data. Data were analyzed in terms of the framework and other hazards mitigation theory found in the literature to produce the findings of the study. There existed many strengths and several weaknesses of the citizen participation aspect of the planning program. Many of the decisions made regarding citizen participation in the FRMP process can be considered successful by the standards set in the literature.
319

Water Storage Capacity and Flow Dynamics in a Papyrus Wetland, Uganda : Implications for Studies of Water Treatment Effects

Asp, Karl January 2009 (has links)
<!--[if !mso]> <object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object><mce:style><! st1\:*{behavior:url(#ieooui) } --> Hydrological investigations were performed in the Lubigi papyrus wetland in suburban Kampala, Uganda, impacted by human encroachment for settlement and agriculture. The first aim was to investigate the water flow variations and the dampening effect of the wetland. A second aim was to estimate the effective wetland volume and area, and relate this to the wetland function for treatment of the suburban runoff. A study site with well defined inflows and outflows was chosen, and three transects were cut through the papyrus to be able to study the water movement beneath the floating papyrus mat. Water flow measurements showed a flow dampening effect of the wetland on peak flows after rains, and the water balance revealed that the precipitation on the wetland was only 4 % of the inflow during the study. The tracer added at the inlet was rapidly detected downstream in the canal in the middle of the wetland, indicating a strong short-circuiting effect of the human made canal. At the outlet the tracer concentration was lower than the detection limit, suggesting a good mixing in the downstream part of the wetland, which was also supported by other water quality measurements in the transects. Ammonium-N concentrations at the inflow and outflow indicated a net export of ammonium-N, but the observed flow variations suggest that intensive water sampling campaigns are necessary for a proper evaluation of the water treatment function. The calculated effective volume and area amounted to 74 and 46 %, respectively, of the theoretically estimated, with a corresponding loss in the flow dampening and water treatment function of the wetland. / Rapporten är ett resultat av ett Minor Field Study stipendium finansierad av Sida.
320

Hochwassersituation im Grundwasser 2010/2011

Wendel, Sibylle, Pöhler, Hannaleena, Scherzer, Jörg 31 July 2012 (has links) (PDF)
Starke Niederschläge im Sommer 2010 führten in Sachsen nicht nur zu regional bedeutsamen Hochwassern, sondern auch zu flächendeckend stark erhöhten Grundwasserständen. Der Bericht dokumentiert die Analyse der Grundhochwassersituation im Winter 2010 bis zum Frühjahr 2011 für den Freistaat Sachsen. Dabei wurden neben Niederschlags-, Abfluss- und Temperaturdaten auch Ganglinien von 126 weitgehend anthropogen unbeeinflussten Grundwassermessstellen des staatlichen Messnetzes statistisch ausgewertet. Mit Hilfe hydrogeologischer Karten wurden regionale Besonderheiten und der Einfluss von Braunkohlenbergbau und Wasserschutzgebieten betrachtet. Die daraus abgeleiteten Grundwasserstandsentwicklungstypen konnten hydrogeologischen Teilräumen zugeordnet werden.

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