Rural Iowa towns often lack flood mitigation because of a lack of resources and inability to compete for federal assistance funds. The Federal Emergency Management Agency relies on a benefit-cost analysis which produces benefit-cost ratios (BCRs) for proposed projects to determine which communities receive funding, with an emphasis on the economic BCR, which compares potential future benefits with estimated capital costs. The FEMA requirement for an economic BCR is at least 0.75. The economic BCRs for mitigation projects in rural towns are often lower compared to those in urban centers due lower potential future benefits from lower building count and potential exposure. Here we use a multijurisdictional approach which analyzes flood mitigation at a watershed scale to join upstream agricultural potential future benefits with downstream potential avoided benefits in rural towns. We predicted BCRs of simulated flood retention wetlands using HAZUS-MH to find the potential future benefits a range of estimated capital costs via a percent reduction approach and a targeted peak flow approach to calculating wetland effects on peak flow. The percent reduction approach generated BCRs of over 0.75 in the Mud Creek watershed for estimated capital costs per wetland up to $177,400. However, the simulated flood retention wetlands did not generate BCRs high enough to meet the minimum requirement in the Hinkle Creek watershed by itself. However, a multijurisdictional approach is not limited to each watershed individually. When the simulated flood retention wetland projects in each watershed were combined, the BCRs were high enough to meet the FEMA requirement. The combined BCRs were over 0.75 for estimated capital costs up to $143,300. The targeted peak flow approach included BCRs which account for dry and wet antecedent soil moisture conditions and minimum, maximum and average peak flow change scenarios. The scenarios with dry antecedent soil moisture conditions created BCRs higher than wet antecedent soil moisture conditions. Further, the maximum peak change scenarios generated BCRs higher than average peak change scenarios, which in turn generated higher BCRs than the minimum peak change scenarios. In the Mud Creek watershed, the only scenario to generate BCRs above 0.75 for any part of the range of estimated capital costs was the maximum peak change scenario under dry antecedent soil moisture conditions. However, the maximum and average peak change scenarios under dry antecedent soil moisture conditions and the maximum peak change scenario under wet soil moisture conditions generated BCRs over 0.75 in the Hinkle Creek watershed. When the simulated flood retention wetland projects for both watersheds were combined, only the maximum peak change scenario under dry antecedent soil moisture conditions generated BCRs above 0.75. We found that a multijurisdictional approach is a viable method for rural watersheds to analyze potential flood mitigation projects to help increase their BCRs.

Currently the Iowa Flood Center (IFC) of the University of Iowa is working in conjunction with the Iowa Department of Natural Resources (IDNR) to create statewide floodplain maps. The IFC has set up a four year plan to construct flood inundation maps for 85 of the 99 counties within the state of Iowa, with the final goal of creating maps acceptable by FEMA. High resolution statewide LiDAR information provides a base dataset from which floodplain maps are produced. Stream centerline data is extracted from a DEM produced by the LiDAR dataset. The centerline information is used in both this project and as a replacement for the USGS NHD streamline for the state. Stream flow estimation for a range of annual exceedance discharges are produced through a USGS recommended combination of regional regression analysis weighted by gage influence. Water surface elevations are produced for each of the annual exceedance discharges through the use of a HEC-RAS one dimensional steady flow model. Flood boundaries are the final product created by HEC-GeoRAS though a comparison of a TIN produced from the water surface elevations and the ground surface DEM. Final FEMA acceptable DFIRM's are produce by the IDNR and submitted to FEMA for adoption into the NFIP.

Pluvial flooding is caused by rainfall events that overwhelm drainage systems and do not allow excess water to be absorbed by soils or water infrastructure. This type of flooding occurs frequently in urban systems and leads to public inconveniences and infrastructure deterioration, which could cost more than fluvial flooding over time. Increased rainfall intensity, which is projected to increase with climate change, could result in increased pluvial flooding. This study aims to examine the vulnerability of pluvial flooding in Portland, OR (2010-2017) by incorporating an interdisciplinary framework that examines the physical and socioeconomic vulnerability of flooding through citizen-reported flooding data. We use a spatially dense network of 5-minute interval rainfall measurement to examine 3-day storm events associated with flooding reports to correlate storm size with the frequency of reports. Additionally, we use a Topographic Wetness Index (TWI) to identify the hotspots of pluvial flooding over space and characterize the sociodemographic and building characteristics of hotspots by performing a spatial analysis using census tract and tax lot level data. We investigate how individual neighborhood characteristics (i.e. ethnicity, education, gender, age, income) and building characteristics (i.e. building type, building age) contribute to reported flooding. This research seeks to identify where pluvial flooding occurs across the city, and how flood management planning can better address flood vulnerability through the biophysical and socioeconomic characteristics that exists amongst communities in Portland.

Extreme flooding of rivers may contribute to increased loading of persistent organic pollutants (POPs) to the Great Lakes, the Mississippi river, and other large lakes and surface waters downstream of industrial and urban areas. This study examines the fate of POPs that were mobilized during heavy flooding of the Cedar River and the small urban city of Cedar Rapids, Iowa during the summer of 2008. This study focuses polychlorinated biphenyls (PCBs). We hypothesize that these PCBs were mobilized by the flood water and that residues remained in the soils and sediments of the residential areas of the city. To test our hypothesis, soil samples were collected from ~200 of residential locations in the downtown Cedar Rapids area and analyzed for the three compound groups. Samples were extracted using an accelerated solvent extraction (ASE 300), and analyzed using GC/ECD, GC/MSD and GC/MS/MS.

Agriculture is one of the major economic drivers and the production is highly dependable on the climatic conditions and very sensitive to the natural hazards like the flood. The Federal Emergency Management Agency (FEMA) of United States developed Hazard-US model (HAZUS), a tool to estimate the loss to several sectors due to natural hazards like floods, hurricanes, and earthquakes. The study assesses the influence of input model parameters for HAZUS flood loss to crops. This thesis analyzes different combinations of input parameters for the Middle Cedar River Watershed in Iowa. The parameters have been modified based on the cropping pattern of the study region and the pricing trends. The results include the computation of the loss distribution and the determination of the most influential parameters. The study has found that some parameters are more influential in the loss estimation. The influence of parameters for the average annual loss (AAL) calculation is similar. Floods at the end of the cropping season are much more severe than floods at the beginning of the cropping season. Corns are more at risk than soybean because of the longer cropping season. Some counties experience more loss than others based on AAL. The results indicate that the agricultural sector is more vulnerable to floods at the end of the cropping season. The estimation of loss can help emergency planning for floods affecting agriculture, and optimize the agricultural resource management. The inclusion of additional parameters like flood velocity and water quality in the model can increase the accuracy of the estimation.

>Magister Scientiae - MSc / The Kars has a well-defined channel along the 62 km stretch from its sources in the Bredasdorp Mountains. After entering the Agulhas plain which has a very low gradient, this river changes into a triangular shaped wetland. This wetland is 7 km in length with no defined channel running through it. The wetland then discharges into another 7 km long channel that joins the Heuningnes River with its mouth at the Indian Ocean. The presence of the wetland causes frequent flooding which affects cultivated lands and a major highway linking towns on the coastal Cape Agulhas area with the rest of the country. Before this study, there was no monitoring of flows along the Kars River including water levels within the wetland. Consequently, the conditions leading to flooding of the wetlands were unknown. This study is aimed at understanding how the combination of local rainfall, Kars River inflow into the wetland, soil characteristics, and the morphology of the wetland influence flooding/inundation. The study monitored river inflows into and outflows from the wetland. A soil survey was conducted within the wetland using the augering method and an infiltrometer to determine soil type and infiltration rates. This was done to assess the hydrological characteristics of the wetland. Using the collected climate data and river flow data, a conceptual model was developed for predicting downstream outflows and possible flood events on a daily timescale. The results indicated that the Kars wetland comprises soil with high silt and clay content, and low infiltration capacity. The wetland causes flood attenuation and diffuse surface flows. Low infiltration rates result in ponding of local rainfall which can contribute to flooding.

>Magister Scientiae - MSc / Improved knowledge is required on the quantity and source of water resources, particularly evident during periods of drought currently being faced in South Africa. There is inadequate knowledge with regards to the flood attenuating properties of wetlands, particularly evident in the ungauged catchments of Southern Africa. This study aims to improve the knowledge on the contribution of flow from tributaries with headwaters in mountainous regions to low lying areas and the effects of wetlands on river flow patterns. Several river flow monitoring sites were established along the major upper tributaries of the Nuwejaars River at which daily water levels were recorded and bi-weekly discharge measurements were conducted. Weather data was collected using four automatic weather stations and three automatic rain gauges’ setup throughout the catchment. Rainfall data coupled with rating curves and daily discharges were used to assess the flow responses of these tributaries to rainfall events. Additionally, stable isotope analysis and basic water quality analysis was used to determine the major sources of flow within the major tributaries. The rainfall and river flow data collected, coupled with the characterization of the wetland was used to determine the flood attenuation capabilities of the wetland. Lastly, a conceptual model based on a basic water balance was developed to further explain the role of the wetland and its effects on river flows. The results showed a 27-hour lag time in peak flows from the upper tributaries at the inflows of the wetland to the outflow. Two of the upper tributaries had flow throughout the year and were fed by springs in the upper mountainous regions of the catchment and all tributaries were largely reliant on rainfall for peak flows. The temporary storage of flows within the wetland occurred as a result of the Nuwejaars River bursting its banks, filling of pools, or ponds and the Voëlvlei Lake. It was concluded that the wetland increased the travel time and decreased the magnitude of flows of the Nuwejaars River. However, due to the fact that wetlands are interlinked on a catchment scale and have a collective effect on flood attenuation this study may be improved by looking at the wetlands within the catchment holistically.

Federal disaster declarations are authorized by the president under the provisions of the Robert T. Stafford Disaster Relief and Emergency Assistance Act of 1988. Prior studies have found varying levels of political influence associated with the declaration process. Factors including electoral votes, reelection years, congressional committee appointments, geographic location, and party favoritism have been implicated in claims of inequity associated with the distribution of federal disaster assistance. Compounding these concerns is evidence of recurring problems associated with disparities in the long-term recovery from disasters based on social and economic factors. This dissertation is a response to the call for further research into the political dynamics of disaster declarations. Multivariate hierarchical analytical techniques and key stakeholder interviews were utilized to systematically investigate perceived inequities in the implementation of federal disaster policy and the consequences of those inequities with respect to health-related recovery in communities that had differential access to federal resources. The research findings counter broad claims of political motive in the distribution of federal resources after disasters. However, the observation of a disproportionate post disaster stress-related disease burden in portions of the study area is indicative of a procedural inequity that must be addressed. The recently enacted Sandy Recovery Improvement Act of 2013 calls for a review of eligibility criteria for disaster declarations. The findings of this research are intended to contribute to the review process and assist in the reformulation of public policy in order to address the unique needs of previously unconsidered at-risk populations.

Masters Research - Master of Science / Recent flash floods and landslides in the Philippines have caused many fatalities, loss of livelihoods; destroyed infrastructures, damaged natural resources and displaced several communities. Investigation of five disaster cases of flash floods and landslides from 1991 to 2006 was undertaken to gain an understanding of the causes, behaviour, distribution and biophysical impacts of these recurrent natural hazards. Sustaining healthy and resilient communities and protecting the ecosystem from natural disasters is a key development goal. Therefore, communities at risk need to adequately prepare for, respond to, and recover from the impacts of these natural disasters. A theory model on community resilience called the Landslip-Disaster Quadrant Model was developed to examine the capacity for resilience and the vulnerability of threatened communities. Six building blocks comprise this Model. A community study of the February 17, 2006 landslides in St. Bernard, Southern Leyte, was conducted to test and refine this Model. Major findings of the study have revealed that flash floods and landslides have been frequent due to changing climatic patterns and greater interaction of natural processes. Extreme weather conditions have resulted in intense rainfall that seeps through fractures and cracks in the ground. Rains saturate and loosen soil particles, weaken slope resistance, triggering landslides that formed natural dams. Failure of these natural dams or log jams caused flash floods and debris flows. The rapidity and destructiveness of these hazards were influenced by the angular position of sliding materials, slope resistance, type of cascading materials caught in the flow, river channel configuration, and human structures that obstruct and/or intensify overflow. These were the physical conditions of vulnerability to disasters in the five cases of natural disaster investigated. Rural livelihoods and the economic base of the local people in Saint Bernard, Southern Leyte, were limited and subsistent. Though the local people have a high literacy rate, they have inadequate understanding of the natural processes associated with landslides. Natural observations such as receding water levels in the river, fractures and cracks in the ground on the mountain, excessive rains and landslides in nearby communities could have been used as early warnings by the local people and authorities for safe evacuation. Many lives in Guinsaugon village could have thus been saved from the deadly landslides of 17 February 2006. Political interests have affected progress of resettlement housing and development projects that obliged many local people to extend the period spent living in the evacuation centres. However, the local people were expressive of their faith and hope to rise from the tragedy. These ‘bouncing back’ attitudes of the local people were indicative of their strong cultural values that formed the core of their coping capacity for natural disasters. The results of the community study tested and refined the Landslip-Disaster Quadrant Model. Among the six blocks for building a disaster-resilient community, cultural values and local norms ranked first. This is followed by ecological security, then livelihood sufficiency and economic base, and further by human health and wellness. The last two blocks were structural networks and institutional arrangements, and political will and priorities. This Model could form the framework for a Comprehensive Landslide and Flash Flood Disaster Risk Assessment in the Philippines. The community assessment toolkit developed in this study could be expanded further into policy and planning guidelines of the National Disaster Coordinating Council of the Philippines.

Abstract not available