Flooding is a major threat to coastal and inland communities in the state of Florida. There are a variety of reasons for the increasing risk of flooding, such as hurricanes, torrential downpours, sea level rise, and storm surge/tides. This paper will focus on Nassau County, the most northeastern county in the state. While the area is affected by most of the aforementioned flood become more prominent over the years and will continue to impact the safety and well-being of coastal communities. In this context, planning for the future entails conducting multi-hazard analysis of risks posed by current and future storm events. This study undertakes a comprehensive analysis of flood risks in Nassau County, Florida, and examines current and future zoning and land use plans and buildings codes to provide science-based recommendations for addressing these risks. / Includes bibliography. / Thesis (MURP)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Paleoflood data are restrictive reflections of climatic conditions, representing one component of a region's climate; high rainfall intensity storms. In regions with a fairly simplistic, uniform hydroclimatological setting (floods above a given magnitude threshold are caused by predominantly one type of atmospheric circulation pattern), the temporal distribution of floods reflects that of the causal circulation pattern. Slackwater-deposit-based paleoflood reconstructions for three rivers in northern Australia cover an aggregate of 1200 years. Slackwater deposits (SWD) are fine-grained sediments which settle from suspension in low velocity areas during floods. These deposits approximate the flood's high water level, and allow reasonably accurate estimation of discharge. Radiocarbon dating of associated organics, and thermoluminescence (TL) dating of the 90-125 μm quartz fraction of the sediments, produce a paleoflood chronology. In this study, radiocarbon ages on SWD ranged from 1200 yr BP to modern, while TL ages on SWD and other fluvial sediments ranged from 2.6 to 60 ka. TL dating appears to have a large temporal range (1-100 ka) and a restricted spatial range (the lower reaches of a basin), while radiocarbon dating has a more restricted temporal range (0-35,000 yr BP) and a large spatial range (anywhere in the basin). The northern Australian paleoflood data formed clusters at 300-440 yr BP and 160 yr BP-present. This distribution is attributed to variations in the intensity of the El Nino/Southern Oscillation (ENSO) circulation (which prevents floods from occurring in northern Australia), and the anti-ENSO circulation (which is associated with large floods).

Flooding in semi-arid streams is highly variable but distinguished from its humid counterpart in terms of forcing conditions, landscape response, flood severity, and stream-aquifer connectivity. These floods have the potential for great benefit in a water-limited environment, but also great devastation when powerful floods encounter human infrastructure. This dissertation employs an integrative approach to address several facets of flooding in semi-arid streams. In particular, information from field sampling during flood events combined with modeling are used to evaluate the processes of post-disturbance sediment transport, flood routing, transient bank storage, and stream disconnection. The major findings show: (1) Suspended sediment composition in floods following wildfire depends on the number, timing, and intensity of preceding storms and flood events, implicating overland flow hillslope processes as a dominant mass wasting mechanism (2) Isotopic chemographs for two representative intense convective storm events demonstrate that the flash flood bore develops from predominantly high elevation event water that overcomes, incorporates, and pushes baseflow to the front of the hydrograph peak (3) Isotope information combined with a plug-flow model can simulate this flood bore mixing process simultaneously in two separate canyons in the basin in order to calculate the timing and quantity of flow; this could be a useful tool for watersheds that are not extensively instrumented, or for calibrating a more complex or distributed model, (4) For a stream connected to an underlying aquifer, a circulation pattern develops at the onset of flooding that causes an upwelling of antecedent water into the unsaturated zone, challenging the assumptions of one dimensional, lateral flow and transport into the streambank, and (5) For small stream-aquifer disconnections, large increases in infiltration, large decreases in seepage, and a dominantly vertical profile for floodwater were observed. This implies that a stream that supports a wide riparian corridor may be in danger of vegetation die-offs with even shallow depletions of the groundwater table.

This thesis examines household behaviour at the intersection of natural disasters and conflict. I structure this research around four distinct analytical chapters that use empirical microeconomic analysis to study household-level decisions and outcomes in the year following the 2010 floods in Pakistan. I first examine how does conflict affect household access to cash transfer programmes, and what mechanisms explain such effects. Using IV estimation to overcome endogeneity of conflict exposure and cash transfer receipts, I find that conflict reduces household and community level access to two large cash transfer programmes in Pakistan. The effects are driven by the likely presence of armed rebel groups who possibly resent state-led efforts to win legitimacy through social protection programmes. Next, I examine the effect of conflict on household access to remittances. I use IV estimation to overcome the endogeneity of conflict and remittance receipts and find that conflict exposure reduces household remittance receipts. This effect is driven by security threats associated with armed group presence, which threatens the operations of informal money transfer agents. Further, I find evidence for conflict negatively affecting investment-focused remittances as the effects of conflict are strongest among households more likely to use remittances for investment, than for consumption. These findings are in contrast to the macro literature that tend to view conflict as a factor that affects altruistic motives of remittances but has not examined investment motives in detail. In my third analytical chapter I examine the unintended effects of household aid receipts on violence through a mechanism that has not been studied in much detail: civilian militarisation through the purchase of guns. Using propensity score matching to overcome selection bias, I find that overall, flood relief cash transfers did not lead to any increases in household gun ownership. However recipients who own large tracts of land and live in conflict-affected areas were 8.3% more likely to acquire a gun, compared to a matched group of non-recipient households. The effects are driven by households that lived in displacement camps, which may have enhanced security concerns and the need for guns. This suggests that for groups that have low material but high security needs, exogenous increases in cash, through cash transfers, can increase the likelihood of acquiring guns for use, or for signalling, as a safety good. Finally, I examine the under-studied role of uncertainty of disasters in affecting post-disaster short-term migration decisions. I find that while flooding exposure increases the propensity to migrate, a higher level of uncertainty, represented by more anomalous floods (compared to recurring floods), decreases migration. I also develop a measure of flooding anomaly, based on the likely past exposure to floods at the community level, using satellite data on long term precipitation levels, and distance to the nearest rivers. My research examines important, but hitherto under-studied and challenging relationships that play out in complex emergencies, where many households simultaneously face flooding and violent conflict shocks. The findings are relevant for economic theory, empirical analysis and for policy.

Thesis (M.S.)--University of Delaware, 2007. / Principal faculty advisor: Brian Hanson, Dept. of Geography. Includes bibliographical references.

Interdisciplinary and unconventional research methods offer important insights into geomorphic, hydrologic and hydroclimatologic characteristics of large floods that are often difficult or impossible to resolve in the framework of conventional flood analysis. Four detailed studies of modern floods, historical floods, and paleofloods in western and central Arizona demonstrate the benefits of analyzing recent and historical extreme floods within the conceptual framework of paleoflood hydrology and flood hydroclimatology. Analysis of the hydroclimatological and paleohydrological context of extreme flooding in Arizona during the winter of 1993 provides a detailed analog to the likely climatic, meteorologic, and hydrologic conditions associated with the largest events in the regional paleoflood record. Investigation of the distribution of relict high-water evidence from extreme floods on the lower Verde River in 1993 improves the accuracy of the river's paleoflood record and reveals interesting hydrological phenomena of extreme floods in the Verde River Basin. A multidisciplinary study of the extraordinarily large Bronco Creek, Arizona, flood of August 1971, shows the original estimate to be significantly overestimated because of complex flow behavior of an extreme flood and the related dynamic morphological response of a high-gradient alluvial channel. The approach to this study is a template for similar analyses of extreme floods and extraordinary flood discharge estimates. A similar, more comprehensive application of paleoflood research methods is demonstrated by the compilation of a detailed regional chronology of flash-flooding in small desert drainage basins (7-70 km²) in western Arizona. The occurrences of large, recent and historical floods were documented with nearly annual resolution, and a 1200-year regional paleoflood record was compiled. Comparison of these records to conventional regional flood-frequency relations indicates that the regional equations are probably inaccurate because of data limitations. The study presents a viable approach to developing a quantitative assessment of regional flood frequency in areas with no conventional data on real floods. The results of each of these studies extend the spatial and temporal scope of the paleoflood and historical flood record of the lower Colorado River Basin and provide further support for the concept of a regional upper limit to flood peak magnitudes.

In the United States, the flood frequency analysis guidelines described in Bulletin 17B are followed to provide reliable flood discharge magnitude estimates for urban floodplain planning and flood insurance studies. The statistical analysis in Bulletin 17B has various assumptions, including that floods are generated by the same type of atmospheric mechanism (flood homogeneity). However, these assumptions should be carefully assessed before proceeding since they might not always be valid and could increase the potential for flood risk. This study focuses on flood frequency analysis from the perspective of flood heterogeneity, the hydrometeorological genesis of each flood event, in Arizona. This was done by analyzing the occurrence and magnitude of individual flood events, which were classified by their flood-producing atmospheric mechanism. Flood frequency curves were derived for each mechanism and combined using a new approach involving the Partial Duration Series peaks. The combined frequency curves were then compared to curves derived from the standard Bulletin 17B method. Results showed that in southern Arizona, the dominant flooding mechanism is characterized by brief, intense, and localized convective precipitation in the summer. However, the dominant flood-producing mechanism in the central Arizona topographic transition zone and at higher elevations is characterized by prolonged and widespread precipitation from synoptic activity in the winter. Tropical cyclone-enhanced precipitation is also an important, but infrequent, flood-producing mechanism throughout the state. Overall, the dominant mechanism does not necessarily produce the largest floods. In such cases flood heterogeneity can have a strong influence on the discharge estimates for the most extreme upper tail probabilities calculated from the flood frequency analysis. Thus, the most frequent floods may impose very little risk of flooding while uncommon floods can impose a much larger one. These results suggest that the flood homogeneity assumption is not valid in many Arizona watersheds. To produce the most accurate discharge estimates possible, it is critical that both analysts and flood managers become aware of the potential repercussions if these details are overlooked.

No description available.

Thesis (Ph.D.)--Tufts University, 2002. / Adviser: Richard M. Vogel. Submitted to the Dept. of Civil and Environmental Engineering. Includes bibliographical references (leaves 95-105). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.