Thesis--Wisconsin. / Includes bibliographical references (leaves 136-143).

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The aim of the research was to evaluate the processes that determine P stability in riparian floodplain soils, with emphasis on chemical transformations in flood-drained calcareous soil. Flooding of soil columns showed an increase in P solubility (from 0.01 to 1.2 μg ml-1) largely due to the reductive dissolution of Fe minerals (solution Fe increased from < 0.05 to > 50 μg ml-1) and increased solubility of Ca-P minerals (solution Ca increased from < 100 to > 1000 μg ml-1). The periodic drainage of the flooded soil exported the equivalent of approximately O.l5 kg ha-1 (over six flood-drain cycles). Exported P correlated with soil solution P immediately before drainage (r2 = 0.99; P < 0.001). After drainage, there was a reversal of the reactions described above, with solution Fe, Ca and P returning to preflooding levels. Over the course of the 6 flood-drain cycles inorganic P became more stable, with Ca-P and Fe-P pools increasing (from 9 and 11 % respectively both to 14 % of TP) at the expense of labile pools. Similar patterns of P release and retention were observed during batch incubation studies of aerobic - anaerobic cycles using moist soil samples. Solution P and Fe were strongly correlated in both non-calcareous (r2 = 0.96) and calcareous (r2 = 0.73) soils. The role of Ca-P mineral solubility was disguised by the dissolution of calcium carbonate. Drying of the soil can lead to P release on re-wetting (up to eight-fold). This is most likely due to a release of P from ruptured microbial cells and transformations of Fe mineral surfaces. Monitoring suggested that all of these processes were active in the field, as the water table advanced and receded, though more slowly than in the laboratory. Over a four month flood-drain cycle losses of dissolved P from the floodplain were estimated at 0.034 kg ha-1. It is unlikely that this is significant relative to upstream inputs of P to the river from point sources and other types of agricultural land in the River Thames catchment.

Thesis (Doctorial)--Universität Leipzig.

The objective of this thesis is to explore the relationship between street patterns and floodplains. Although some researchers have written about the relationship between land use and floodplains in The Woodlands, few have discussed how the city form was designed around the hydrological system. This thesis will focus on one aspect of the city form, the street pattern, to determine the effectiveness of street designs' response to floodplains. Unlike the grid-like pattern advocated by the New Urbanists, street patterns in The Woodlands are loops and cul-de-sacs -- a typical suburban pattern at the time it was developed; however, street patterns adapt to the boundaries of floodplains and protect them very well. Using a GIS tool to overlay 100-year floodplains on the street layer, it is clear to see that there are low percentages of streets in the 100-year floodplains. Thus, The Woodlands employed nonstructural techniques to mitigate flood hazard, which minimize the development in floodplains. Flood control in The Woodlands is much better than other places in the Houston area. From flood control and the protection of the natural environment standpoints, the nonstructural techniques are advocated more than structural techniques for floodplains in the development management. Therefore, the design of street patterns in an area is determined by both the aim of convenient transportation and the aim of hazard mitigation.

A study was supported by SUS/STAR to investigate the fate of heavy metals in bridge runoff which are received by surrounding floodplains. Three bridge sites in Central Florida were selected and various locations in each site were sampled. Soil, plant, and water samples were analyzed for Cd, Zn, Cu, Fe, Pb, Ni and Cr. Statistical analysis of results for heavy metal content of plants and soils at control versus bridge sampling areas were conducted. In agreement with other investigators, Pb was found to be a good indicator of highway pollution in soil, plants and water. Possible mechanisms for metal sorption were developed from laboratory sorption experiments. Soil capacities for lead increased with increasing pH, organic content, and soil buffering capacity. Also, information about the types of heavy metal compounds in a floodplain was obtained using various extraction solutions.

Tennessee has a long history of floods that have caused property damage and loss of life. In the face of climate change and variability, it is imperative to look at trends to ascertain if there is a significant change in current flood regimes versus past flood events. Trend Analysis and Emerging Hotspot Analysis are useful geospatial tools that can effectively display changes over time and space. This study aims to evaluate the history of flood events in Tennessee to identify spatiotemporal trends and hot spots. A total of 902 flood events from 1996-2021 recorded in the National Oceanic Atmospheric Agency (NOAA) storm events database were analyzed using the number of events per county and the total damages per county at an annual time step. Two 26-year space-time cubes were built in ArcGIS Pro (version 3.0) for flood events and damages using an annual time step, with counties as the spatial unit. GeoGa software (version 1.20.0.22) was used to weight the distance between Tennessee counties to define a statistically significant neighborhood distance at 37km fixed distance. Trend Analysis and Emerging Hotspot Analysis was conducted to assess spatiotemporal trends in flooding events and damages (in dollars). Trend analysis revealed an increasing trend of flood events in eleven counties in middle Tennessee (Davidson, Wilson, Rutherford, Coffee, Marion, Putnam, Overton, Maury, Lawrence and Dickson counties) and Carter county in east Tennessee. Decreasing trends were observed in two counties (Lake and Bradley), all at a 90% or greater confidence level. Increasing trends in flood damages were identified in Cumberland, Putnam, Lawrence, Blount, Sullivan and Green counties, all in east and middle Tennessee. Decreasing trends were identified in Lake, Obion, Dyer, and Tipton, all in west Tennessee. East Tennessee was identified as a sporadic flooding hot spot (Hawkins, Green and Washington counties) with no significant hot spots in middle and west Tennessee. There were no hot spots nor cold spots in flood-related damages across Tennessee. The results indicate that flood events and related damages are decreasing in west Tennessee while parts of middle Tennessee and east Tennessee are experiencing increased flood events. This study is an important step to better understand spatiotemporal trends in flooding and flooding damages and will be useful in hazard mitigation planning in Tennessee at both state and county levels.

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No description available.