Browsing by Subject "Flooding"

Now showing 1 - 5 of 5

Open Access
A Perfect Storm: The Effect of Natural Disasters on Child Health
(2022-08-01) Quijano, Cheyenne
Typhoons have destructive effects on child health, particularly by increasing the risk of waterborne disease, a leading source of illness and one of the foremost causes of death in children under age 5. To quantify this phenomenon, I examine the health effects of flooding after Typhoon Labuyo in the Philippines, a country at the center of the Pacific Typhoon Belt, the area most vulnerable to severe typhoons and flooding. I use a spatial regression discontinuity design, comparing children living in a flooded barangay (town) to children living just outside of a flooded area. Results do not show any significant relationship between flooding and incidence of waterborne disease. However, my specifications confirm previously established relationships between controls and incidence of disease. Because health and flood data were collected the day after Typhoon Labuyo left the Philippines, I am able to examine differences between the short-term and medium-term impact of flooding on child health. Subgroup analyses show that flooding decreases waterborne disease incidence, in contrast to my predictions, and that the effect is more pronounced in the medium-term than in the short-term. Discrepancies between my predictions and results may be due to the limited resolution of my flooding data, harming my ability to identify which children truly experienced flooding. This paper also introduces a flood measure that accounts for incidence and intensity using NASA satellite data. Overall, my research provides insight into the global effect of typhoons. Understanding the detrimental health effects of flooding is critical as climate change exacerbates natural disaster events, disproportionately affecting the most vulnerable.
Open Access
Building Social Equity into Floodplain Buyouts
(2021-04-30) Lipuma, Sarah
Increasingly frequent flood events have generated greater attention to voluntary floodplain buyouts, a tool to mitigate flood hazards by permanently moving people and properties out of harm’s way. While buyouts hold the promise of reducing flood risk by allowing the land to be used to store stormwater, they can also repeat inequitable practices of the past that have displaced vulnerable communities. Through a literature review, this study discusses the knowledge to date at the nexus between flood risk, social equity, and buyouts. The study uses geospatial tools to identify possible parcels for buyouts in a North Carolina town by focusing on the level of flood risk and proximity to natural areas. The resulting buyout scenarios are compared using a social vulnerability index and physical risk factors. The study concludes with recommendations to land use planners and floodplain managers at the state level for buyout decision-making. Incorporating social vulnerability information into buyout criteria will be valuable to administrators of buyout programs to identify the most at-risk populations, prioritize equity, and direct government funding to buyouts that benefit the entire community.
Open Access
Deforestation and Flooding in the Lower Roanoke River Basin
(2022-04-22) Zeng, Yingfan
The large natural forest ecosystems in the Lower Roanoke River Basin, in northeast North Carolina, are home to numerous and diverse plant and animal species. However, these unique and precious forest ecosystems have been progressively threatened by deforestation and flooding in recent decades. Logging, agriculture, development, recreational use, and reservoir construction all could cause direct loss of floodplain forests. Changes in landscape, especially deforestation, conducted on the floodplains can cause indirect impacts on the floodplain hydrology. For example, flood events may occur with greater frequency in some areas due to increased upstream impervious surfaces and loss of vegetation buffers. At the same time, dams altered the natural flow, and in particular, have impacted the timing and intensity of overbank flow into the floodplain. This change in hydrology and flooding may lead to consequences for the floodplain plant and animal communities. The objectives of this project are to deepen the understanding of the 2 interacted factors of deforestation and flooding concerning the Roanoke River Basin by 1). investigating the deforestation trends in the past 20 years, 2). analyzing the flood frequencies and duration in recent years, and 3). mapping the flood extents by a remote sensing model. Temporal and spatial trends of deforestation in the Lower Roanoke River were analyzed by the forest loss data from the Global Forest Change database accessed on Google Earth Engine, and the vegetation species of the removed forests were investigated. Over the past 20 years, there were about 1290 km2 of forest loss happened in the Lower Roanoke River Basin, of which 610 km2 in 2001-2010 and 680 km2 in 2011-2020. Over the same 10-year period, forest loss increased by 11.5% after 2010. Spatially, deforestation was mainly distributed on the downstream banks and increased in these areas after 2011. In the past 2 decades, 8.1% or 48 km2 of deforestation occurred in the 100-year floodplain. Similar to the total deforestation, the forest loss areas in floodplains also increased after 2011 but at a higher increase rate of 18.8%. The largest loss of vegetation species in deforestation areas was hardwood. Oak - Sweetgum Floodplain Forest was the most removed vegetation type in both the floodplains and it was also the second-largest vegetation type of the deforestation areas in the whole basin before and after 2010. The flow in the Lower Roanoke River Basin is heavily dominated by 3 upstream dams. Given the dam capacity and empirical observations, a flood event was defined as a continuous period of that discharge of the Roanoke Rapids Dam above 20,000 cfs in this study. All such periods from 2016 to 2021 were screened, and there were 25 flood events in total. During the 6 years, the number of flood events ranged from 1 to 6, showing a seasonal trend of more flood events in winter and spring, and less in summer and autumn. In addition to flood frequency, the inundation time in the floodplain forests was studied by the continuous water level data from 14 monitoring sites along the Roanoke River. For all the flood events, the time required for the forest to dry out varied widely, with an average of 25 days to 40 days. For the monitoring sites, the upstream monitoring ones were underwater for a longer time, the downstream sites needed a medium time, and the sites in the middle basin went back dry the most quickly. Another important finding was the inundation in the forests needed a long time to recede. Even though the dam discharge periods were only about 1-2 weeks, the water remained on the floodplain for up to 57 days. In summary, the floodplain forests were under serious flooding pressure because of the long inundation time, which varied a lot, depending on location, flood events, topography, land cover, and other factors. It is very necessary to understand where the inundated forests are during flood events to study how forest ecosystems respond to flooding stress. A remote sensing model using Sentinel-1 radar data was built to identify the flood extent of a specific flood event by a random forest machine-learning algorithm. The flood extents of 2 flood events in March 2019 and March 2021 were mapped. The resulted flood extent maps had high accuracies. The overall accuracy for March 2019 was 85.6% and that for March 2021 was 89.7%. The most common misclassification was between dry forest and flooded forest due to their similar remote sensing signatures in the predictor composites. Both flood extents overlapped well with the 100-year floodplain in the middle and lower basin, validating the 100-year floodplain was a good predictor of flood extent in this area. But there were areas flooded in both events but not on the floodplain, which needed special attention to flooding. In conclusion, forest loss was accelerating in the Lower Roanoke River Basin, especially on the floodplains. The basin was still at high risk of flooding in winter and spring, and the floodplain forests would be under high flooding pressure because of the long time for water to recede. Remote sensing, in particular with radar data, had been proven as a feasible way to map the flood extent of a specific flood event, which can be a good reference for forest management and dam management. With deforestation and flooding both considered, the 100-year floodplain should be the focus of forest management and conservation work in the Lower Roanoke River Basin. Increased knowledge about shifts in forest practices, water flow responses, and flood extents may inform and benefit future land, forest, and dam management in the Lower Roanoke River Basin.
Open Access
Flooding outside the floodplains: Evaluating pluvial flooding in the Ellerbe Creek Watershed
(2017-04-28) Rao, Mahima Ramakant; Weidenbach, Mikia
Flood-related policies and programs have historically focused on riverine and coastal flooding, overlooking the potential impact of pluvial flooding. Pluvial flooding occurs when the rainfall rate exceeds the capacity of the ground to absorb water and/or drainage systems’ ability to carry away water. This process is exacerbated in our increasingly urban landscapes where impervious surfaces preclude infiltration of rainfall into the ground. This project aims to encourage stakeholders to invest in studying and managing pluvial flooding through two objectives: 1) Identifying areas prone to pluvial flooding in the Ellerbe Creek Watershed using EPA’s Stormwater Management Model (SWMM) and 2) integrating the pluvial flood map into the ongoing watershed protection projects of our client, the Ellerbe Creek Watershed Association (ECWA), by building a GIS-based Strategic Planning Tool using R software. This work reflects ECWA’s mission statement to move Durham to be an example for proactive urban stormwater management.
Open Access
In the News: Discourses of Climate Change East of I-95 in North Carolina
(2023-04-28) Mackinson, India; Ballardo, Gabriella; Halbert, Corey
For coastal North Carolinians, the names Matthew and Florence conjure memories of water, wind, and destruction. These deadly hurricanes will be far from the last – eastern North Carolina faces projections of increasingly severe hurricanes and coastal flooding due to climate change. In a state famous for its division on climate change science and action, we ask how significant events in the 2010s, such as natural disasters and political moments, shaped climate discourse in its flood- prone eastern counties. We chose four North Carolina local newspapers for our analysis, as research shows local media sources present useful information on community perceptions and experiences. These newspapers represent a varied set of counties based on socioeconomic and geographic indicators, allowing us to create a more nuanced picture of the discourse over temporal, spatial, and social scales in a diverse region. The results of this work will aim to better understand what factors influence the evolution of climate change discourse over time.