Anaerobic conditions resulting from flooding often lead to enhanced release of phosphorus (P) to overlying water. This study examined the effect of flooding and anaerobic conditions on soil P dynamics. A field ponding study using Scanterbury heavy clay soil (unamended, inorganic fertilizer- or manure-amended), and a laboratory incubation study using 12 soils (unamended or manure-amended) from Manitoba showed that P release to flood water under reduced conditions varied substantially. In the field ponding study, flooding and development of anaerobic conditions did not enhance P release into surface flood or soil pore water. In the incubation study, the response to flooding and anaerobic conditions ranged from a small decrease to a 15-fold increase in dissolved reactive P concentration (DRP) in flood water. Partial least squares analysis indicated that measures of degree of P saturation in soils can effectively predict DRP concentration changes in surface flood water under anaerobic conditions.

The purpose of this research is to adapt and improve existing two-dimensional numerical tidal models so that they can cope with regions where the tide falls and rises to uncover and cover inter-tidal banks without incurring numerical shocks which may be caused by the discretization of time and space. This thesis presents a review of current practices in the numerical modelling of flooding and drying banks in two dimensions. A two-dimensional depth-averaged numerical model has been written and is presented. It is used as a tool with which to investigate various existing algorithms which represent the physical process of the wetting and drying of intertidal zones. An alternative method with which to represent the moving boundary has been developed. This method is free from disturbances usually caused by the implementation of a moving boundary in such a numerical scheme. A 2NM numerical model of the Wash, U.K., is run to provide hind-cast tidal data pertaining to a particular site and period. A field programme is established to provide validation data for the model. Finally, conclusions from the programme of research are drawn.

The shoreface, the 'buffer zone' between the land and sea, is one of the most important coastal regions directly influencing the coastal sediment budget through its role as a sediment sink or source. It therefore has a potentially significant impact upon large-scale (10 km; decades) shoreline movement. However, knowledge of shoreface activity over the medium- (I km; years) and, more particularly, the large-scale remains scarce, primarily as a consequence of data limitations. This empirical thesis extends existing knowledge to the large-scale through the observation of the temporal and spatial characteristics of shoreface morphodynamic behaviour over a 32 year period. It takes a data-orientated approach using the unique JARKUS data set which is composed of cross-shore bathymetric profiles covering the entire Holland coast to a maximum offshore distance of 3 km (approximately 16 m depth). The observations made are also used to i) evaluate the ability of existing models to predict shoreface morphodynamic behaviour; and ii) examine the evolution of shoreface activity beyond the data limits. It is shown that not only is there a cross-shore limit to significant depth change on the upper shoreface (as previously observed in short-scale studies), but over the longer temporal periods (2: 10 years), the middle and lower shoreface typically undergoes significant erosion. These observations are forthwith named the 'shoreward depth of closure' and 're-opening zone', respectively. The observed shoreface activity has also been classified as a function of the cross-shore extent of the activity as either 'non-', 'partially-' or 'fully-active'. Shoreface activity is strongly spatially- and temporally dependant, such that i) the Holland coast can be divided into two longshore provinces of similar morphodynamic characteristics; and ii) after 100 years, the north Holland shoreface is predicted to become fully active i. e. there is no cross-shore limit to the activity. Shoreface processes are under the control of internal dynamics e. g. the nearshore bar system, and external forcing e.g. hydrodynamics. The relative significance of these forcings is temporally dependent; for example the nearshore bar system has a greater relevance on the upper shoreface activity over the shorter time periods. Although most readily applicable to wave-dominated coastlines with similar characteristics to the Holland coast e.g. a near shore bar system, the fundamental ideas arising from this work could also be applied to coasts with different environmental conditions e.g. tidally dominated. Essentially this study shows that shoreface activity is more widespread in the cross-shore than previously appreciated. One consequence is that there will be a greater sediment volume in transport than formerly acknowledged and accounted for in, for example, sediment budgets.

A counter current annular flow experiment was performed to determine flooding conditions for varying degrees of subcooling using steam and water. The findings can be used in reactor safety codes to provide an improved model of flooding during accident analysis. The test section is a stainless steel tube which is approximately a 5/16 scale version of a pressurized water reactor (PWR) surge line. The water flows in an annular film down the inside of the tube and steam flows upward through the annulus. Flooding is the point at which the water film reverses direction and begins to travel upward. Flooding tests were conducted at atmospheric pressure for water flow rates between 3.5 gallons per minute (GPM) and 11 GPM and water inlet temperatures between 35 degrees C and 97 degrees C. The data obtained at high water subcooling indicate a significant departure from accepted flooding correlations developed for air-water systems which is expected because vapor condensation alters the steam inlet flow rate needed to induce flooding. The data more closely follow air-water data at low subcooling. Such data has not been seen in the literature for steam-water flooding experiments in a large diameter vertical tube and will serve as an important benchmark.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Mountain snowline is important as it is an easily identifiable measure of the phase state of water in the landscape. However, frequent observation of the snowline in Scotland is difficult as reduced visibility is common, obscuring ground based and remotely sensed methods. Changes in seasonal snowline elevation can indicate long-term climate trends. Snow cover influences local flora and fauna, and knowledge of snowline can inform management of water and associated risks. Complete Scottish Snow Survey of Great Britain (SSGB) records were transcribed and form the primary snow cover dataset used for this work. Voluntary observers collected the SSGB between 1945 and 2007. Other snow cover data used includes remotely sensed (Moderate-resolution Imaging Spectroradiometer: MODIS) and Met Office station observations (as point observations and interpolated to form UK Climate Projections 2009, UKCP09). I present a link between the North Atlantic Oscillation (NAO) index and days of snow cover in Scotland between winters from 1875 to 2013. Broad (5 km resolution) scale datasets (e.g. UKCP09) are used to extract nationwide patterns, supporting these findings using SSGB hillslope scale data. The strongest correlations between the NAO index and snow cover are found in eastern and southern Scotland; these results are supported by both SSGB and UKCP09 data. Correlations between NAO index and snow cover are negative with the strongest relationships found for elevations below 750 m. A degree-day snow model was developed using daily precipitation and temperature data to derive snow cover and melt. This model was run between 1960 and 2011 using point data from five Met Office stations and data on a 5 km grid (UKCP09 temperature and CEH GEAR precipitation) across Scotland. Due to CEH GEAR data underestimating precipitation at higher elevations, absolute values of melt are uncertain. However, relative correlations are apparent, e.g. the proportion of precipitation as melt and number of days with snow cover each year are generally decreasing through time, except around Ben Nevis. Notably, this increase correlates with positive NAO, and it is thought Ben Nevis remains cold enough to accumulate lying snow in the face of a warming climate. Snowmelt rates were found to annually exceed the maximum snowmelt rate used for fluvial impoundment structure design, but this was only at the highest elevations in areas like the Cairngorms.

Due to rapidly changing climate and socio-economic conditions, many coastal areas are becoming increasingly vulnerable to internal and external risks of flooding. Low-lying coastal mega-cities in Southeast Asia are widely recognized as hotspots of flood risk. The Bangkok Metropolitan Region is one of the largest coastal megacities in Southeast Asia that is challenged by the potential impacts of climate change and human activities expected over coming decades. The overarching aim of this research is to evaluate present and future flood risks due to the combined impacts of climate (sea-level, rainfall regime and storm surge) and human (land subsidence and drainage capacity) factors in Bangkok Metropolitan region, Thailand. To design plausible future scenarios, flow and precipitation records were examined using the Log Pearson Type III frequency analysis approach. Land subsidence (LS) and sea level rise (SLR) scenarios were derived from historical records and published studies. Future flood risks (fluvial, surface water, and coastal) were modelled under various combinations of key drivers (SLR, storm surge, LS and increased river flow). The October 2011 flood in Thailand was used as a baseline event for coastal and fluvial flood modelling. Scenarios were designed with projections of LS and SLR to 2050, 2080, and 2100. A two-dimensional flood inundation model (FloodMap) was used to derive coastal inundation depth, velocity and extent associated with each scenario. Coupled modelling of one-dimensional river flow (HEC-RAS) and two-dimensional flood inundation (FloodMap) was undertaken. Surface water flood modelling simulated the 2015 event in model calibration. A two-hour rainfall event that occurred in 2011 was used as the baseline to derive future scenarios with increased precipitation of various return periods and topographies accounting for land subsidence. For each type of flood modelling, sensitivity analysis was first conducted to investigate the effects of mesh resolution and roughness parameters on model predictions. Results indicate that the model is sensitive to both resolution and roughness, but to various degrees, depending on the metrics used in the evaluation. Spatial metrics such as the Root Mean Standard Error, F and point depth are able to distinguish between model predictions and reveal the spatial and temporal derivations between simulations. The impacts of flood risk on critical infrastructure nodes (e.g. power supply, transportation network, rescue centres, hospitals, schools and key government buildings) were then evaluated under various scenarios. Overall, results suggest progressively increased risks of coastal, surface water, and fluvial flooding to critical infrastructures over time from 2050, 2080 to 2100. Flood modelling of coastal and fluvial inundation processes suggests that the combined impacts of individual risk drivers is, in most cases, far greater than any of the individual factors alone. This study demonstrates that flood risks in coastal mega-cities like Bangkok must be evaluated in a holistic manner, taking into account multiple key risk drivers and considering the potential joint-occurrence of various types of flooding. Moreover, where numerical modelling was undertaken and infrastructure data are available, local hotspots of flood risks under various scenarios can be identified, allowing potential adaptation measures to be evaluated within the modelling framework developed. This research is the first to consider multiple flood risk drivers and interacting flood risks within a single modelling framework in the Bangkok Metropolitan Region. It will have long lasting legacy for flood risk management in the region and beyond, enabling more effective adaptation in a changing climate through: (i) raised awareness of multiple risk drivers and interacting flood risks for both the public and policy makers; (ii) further and more complete assembly of various data sets when they become available based on the template demonstrated in this study; and (iii) identification of hotspots of critical infrastructure and communities at risk using refined and alternative modelling approaches within the modelling framework developed in this study.

This study examines historical variations in flood frequency and magnitude in the Yorkshire Ouse basin, northern England, over the last 900 years. The causes of temporal and spatial variations in flooding are evaluated through investigation o f climatic and land-use controls. Documentary evidence o f flooding and climate suggests that a series of large floods between 1263 and 1360 were associated with climatic deterioration from the Medieval Optimum. A shift to generally milder conditions between 1361 and 1549 resulted in no floods being documented in the Ouse basin The frequency o f large magnitude floods increased dramatically between 1550 and 1680, as a result o f low temperatures, increased surface wetness, more frequent snowfall and a southward shift of prevailing storm tracks over middle latitudes, associated with the onset of the "Little Ice Age’. In contrast, during a wanner phase of the Little Ice Age, between 1681 and 1763, the frequency of localised summer flooding increased in the Ouse basin due to more frequent high intensity, short duration convective storms. Extensive lowland flooding became more common between 1764 and 1799 due to an increase in heavy rainfall, followed by a 50-year period characterised by relatively moderate flood frequencies and magnitudes. The later half of the nineteenth century experienced high flood frequencies and magnitudes, particularly in the 1870s and early-1880s, coinciding with high rainfall totals and a high incidence of cyclonic flood generation. Gauged flood and climate data, and land-use records indicate that the period between 1900 and 1916 was characterised by very low flood frequencies and magnitudes, associated with low rainfall, warm temperatures, and an increase in westerly flood generation. Between 1916 and 1943 there were marked variations in flood magnitude between the rural northern rivers and southern industrialised rivers. Magnitudes generally increased on northern rivers, whilst on some southern tributaries of the Ouse, flood magnitudes declined as a result of widespread channel improvement and flood defence schemes. Around 1944 a marked and sustained increase in flood frequency on northern rivers was associated with an increase in the incidence of heavy daily rainfall, greater westerly flood generation and large-scale upland and lowland drainage. Very low flood frequencies and magnitudes between 1969'and 1977 resulted from extremely low rainfall totals. Whereas the most recent period, between 1978 and 1996 has experienced some of the highest flood frequencies and magnitudes on record, associated with an increase in the frequency of floods generated under cyclonic and south-westerly synoptic situations, and a number of land-use changes promoting more rapid runoff including, large increases in upland livestock numbers, an increase in the area under winter-cereals and the cumulative effects of moorland gripping.

Flood waters will penetrate the wall cavities of a home and the wall materials then serve as a substrate for mold development. This study measured the effect of flooding and subsequent drying on the extent and type of mold on different residential wall materials. Wet and dry wall samples were analyzed by cloning and sequencing and twenty-one mold species were identified from above and below the water line. Real-time PCR quantitated selected species on fiberglass batt insulation, gypsum wallboard, wood stud, plywood panels, vinyl siding, and house wrap. The mold species found in the highest concentration were Aspergillus fumigatus, Paecilomyces variotii, Chaetomium globosum, and Stachybotrys chartarum. The batt insulation supported the highest concentration of mold, followed by the wood stud, sheathing and gypsum wallboard. The high level of Aspergillus fumigatus and Stachybotrys chartarum on the wall materials seven months after flooding is a cause for concern.

No description available.