Valuing floodplain protection and avoidance in a coastal watershed.

Flood-related losses in the United States are increasing despite large-scale mitigation efforts. To offset the rising cost of floods, the US Congress passed legislation in 2014 that will augment insurance premiums to make the National Flood Insurance Program more actuarially sound. Consequently, there is interest in lowering flood-related costs to the homeowner, both in terms of premiums and damage. This study addresses the issue by integrating premium savings and damages avoided based on several mitigation scenarios. Specifically, it examines how much policyholders within a watershed near Houston, Texas, could have saved between 1999 and 2009 had their communities introduced specific avoidance-based mitigation activities. The results indicate that homeowners and communities can offset premium rises and a majority of the damage suffered through marginal expansions of such initiatives. However, the costs associated with their implementation could counter some of these savings, and hence they need to be considered in future work.

Household adjustment to flood risk: a survey of coastal residents in Texas and Florida, United States.

Individual households have increasingly borne responsibility for reducing the adverse impacts of flooding on their property. Little observational research has been conducted, however, at the household level to examine the major factors contributing to the selection of a particular household adjustment. This study addresses the issue by evaluating statistically the factors influencing the adoption of various household flood hazard adjustments. The results indicate that respondents with higher-value homes or longer housing tenure are more likely to adopt structural and expensive techniques. In addition, the information source and the Community Rating System (CRS) score for the jurisdiction where the household is located have a significant bearing on household adjustment. In contrast, proximity to risk zones and risk perception yield somewhat mixed results or behave counter to assumptions in the literature. The study findings provide insights that will be of value to governments and decision-makers interested in encouraging homeowners to take protective action given increasing flood risk.

Hurricane Recovery and Ecological Resilience: Measuring the Impacts of Wetland Alteration Post Hurricane Ike on the Upper TX Coast.

Recovery after hurricane events encourages new development activities and allows reconstruction through the conversion of naturally occurring wetlands to other land uses. This research investigates the degree to which hurricane recovery activities in coastal communities are undermining the ability of these places to attenuate the impacts of future storm events. Specifically, it explores how and to what extent wetlands are being affected by the CWA Section 404 permitting program in the context of post-Hurricane Ike 2008 recovery. Wetland alteration patterns are examined by selecting a control group (Aransas and Brazoria counties with no hurricane impact) vs. study group (Chambers and Galveston counties with hurricane impact) research design with a pretest-posttest measurement analyzing the variables such as permit types, pre-post Ike permits, land cover classes, and within-outside the 100-year floodplain. Results show that permitting activities in study group have increased within the 100-year floodplain and palustrine wetlands continue to be lost compare to the control group. Simultaneously, post-Ike individual and nationwide permits increased in the Hurricane Ike impacted area. A binomial logistic regression model indicated that permits within the study group, undeveloped land cover class, and individual and nationwide permit type have a substantial effect on post-Ike permits, suggesting that post-Ike permits have significant impact on wetland losses. These findings indicate that recovery after the hurricane is compromising ecological resiliency in coastal communities. The study outcome may be applied to policy decisions in managing wetlands during a long-term recovery process to maintain natural function for future flood mitigation.

Predicting peak inundation depths with a physics informed machine learning model.

Timely, accurate, and reliable information is essential for decision-makers, emergency managers, and infrastructure operators during flood events. This study demonstrates that a proposed machine learning model, MaxFloodCast, trained on physics-based hydrodynamic simulations in Harris County, offers efficient and interpretable flood inundation depth predictions. Achieving an average R 2 of 0.949 and a Root Mean Square Error of 0.61 ft (0.19 m) on unseen data, it proves reliable in forecasting peak flood inundation depths. Validated against Hurricane Harvey and Tropical Storm Imelda, MaxFloodCast shows the potential in supporting near-time floodplain management and emergency operations. The model's interpretability aids decision-makers in offering critical information to inform flood mitigation strategies, to prioritize areas with critical facilities and to examine how rainfall in other watersheds influences flood exposure in one area. The MaxFloodCast model enables accurate and interpretable inundation depth predictions while significantly reducing computational time, thereby supporting emergency response efforts and flood risk management more effectively.

Examining the 100-year floodplain as a metric of risk, loss, and household adjustment.

An understudied, but central aspect in understanding flood impacts is the way we conceptualize, identify, and delineate risk. The 100-year floodplain is the longstanding metric in the United States for determining and acting upon the possibility of an area being inundated. This spatial delineation guides local planning and development decisions, triggers insurance purchases and other household adjustments, and serves as the fundamental indicator for whether it is safe to build a structure on a particular site. However, increasing evidence suggests that the 100-year floodplain is neither accurate nor sufficient in guiding communities and household decisions to mitigate the adverse economic impacts of floods. In this perspective, we examine the effectiveness of the 100-year floodplain as an appropriate marker of risk. First, we review existing studies on location and flood damage. Next, we apply these concepts to repetitive flood losses data in Harris County, Texas. We conclude that the apparent inability of the floodplain designation to effectively capture the likelihood of property damage and potential loss of human life in coastal areas has left potentially millions of property owners unaware of the flood risk and unprepared to mitigate their adverse impacts. Relying on traditional 100-year floodplain boundaries, local decision makers are hampered in their ability to ensure community development occurs in a resilient manner. Finally, we set forth an agenda for future research to better capture the conditions associated with flood risk and account for the large percentage of damage outside the designated floodplain.

Policy learning for flood mitigation: a longitudinal assessment of the community rating system in Florida.

Floods continue to inflict the most damage upon human communities among all natural hazards in the United States. Because localized flooding tends to be spatially repetitive over time, local decisionmakers often have an opportunity to learn from previous events and make proactive policy adjustments to reduce the adverse effects of a subsequent storm. Despite the importance of understanding the degree to which local jurisdictions learn from flood risks and under what circumstances, little if any empirical, longitudinal research has been conducted along these lines. This article addresses the research gap by examining the change in local flood mitigation policies in Florida from 1999 to 2005. We track 18 different mitigation activities organized into four series of activities under the Federal Emergency Management Agency's (FEMA) Community Rating System (CRS) for every local jurisdiction in Florida participating in the FEMA program on a yearly time step. We then identify the major factors contributing to policy changes based on CRS scores over the seven-year study period. Using multivariate statistical models to analyze both natural and social science data, we isolate the effects of several variables categorized into the following groups: hydrologic conditions, flood disaster history, socioeconomic and human capital controls. Results indicate that local jurisdictions do in fact learn from histories of flood risk and this process is expedited under specific conditions.

Repurposing Vacant Land through Landscape Connectivity.

Storm surge protection systems have proven effective in protecting populations in developed areas and can allow for development in otherwise potentially flood-prone areas. Resultant intensification of land conversion can result in large scale habitat fragmentation. Simultaneously, urbanized areas worldwide are increasingly accumulating large amounts of vacant land, creating an unprecedented opportunity to improve green space networks and natural systems. This article describes creation of a regional growth framework that balances the need to repurpose vacant lots with the provision of ecosystem services. The analysis seeks to maximize the structural connectivity of the landscape by using high ecological potential of vacant lands as a device for linking existing habitat patches, wildlife conservation areas, wetlands, riparian corridors, and small-scale green spaces. The research uses raster-based suitability models generated in ArcGIS to determine development potential and ecological values of vacant land parcels. Vacant lands having low development potential and high ecological value are linked spatially to create ecological corridors among patch areas using a least cost path connectivity model generated with Linkage Mapper software. Results indicate that vacant land can connect existing ecological patch and core areas with relatively minimal negative impact on development potential while simultaneously enhancing provision of ecological services. The approach provides a model for an ecological based solution to repurposing vacant urban land.

Understanding the Notion between Resiliency and Recovery through a Spatial-Temporal Analysis of Section 404 Wetland Alteration Permits before and after Hurricane Ike.

Historically, wetlands in the United States have been lost due to agriculture, anthropogenic activities, and rapid urbanization along the coast. Such losses of wetlands have resulted in high flooding risk for coastal communities over the period of time. In addition, alteration of wetlands via the Section 404 Clean Water Act permits can increase the flooding risk to future hurricane events, as the cumulative impact of this program is poorly understood and under-accounted. Further, recovery after hurricane events is acting as an encouragement for new development and reconstruction activities by converting wetlands under the wetland alteration permitting program. This study investigates the degree to which hurricane recovery activities in coastal communities are undermining the ability of these places to absorb the impacts of future storm events. Specifically, this work explores how and to what extent wetlands are being affected by the federal permitting program post-Hurricane Ike in 2008. Wetland alteration patterns are examined across three counties (Harris, Galveston, and Chambers County) along the Texas Gulf Coast over a 10-year time period, from 2004-2013 (five years before and after Hurricane Ike) by conducting descriptive spatial analyses. Results indicate that after Hurricane Ike, the number of permits substantially increased in Harris and Chambers County. The vast majority of individual and nationwide type permits were issued within the 100-year floodplain, storm surge zones, and areas damaged by Ike flooding, suggesting that recovery after the hurricane is compromising the ecological resiliency on which coastal communities depend. The authors expect that the findings of this study can increase awareness to policy makers and hazard mitigation planners regarding how to manage wetlands during a long-term recovery process to maintain their natural functions for future flood mitigation.

The contribution of mangrove expansion to salt marsh loss on the Texas Gulf Coast.

Landscape-level shifts in plant species distribution and abundance can fundamentally change the ecology of an ecosystem. Such shifts are occurring within mangrove-marsh ecotones, where over the last few decades, relatively mild winters have led to mangrove expansion into areas previously occupied by salt marsh plants. On the Texas (USA) coast of the western Gulf of Mexico, most cases of mangrove expansion have been documented within specific bays or watersheds. Based on this body of relatively small-scale work and broader global patterns of mangrove expansion, we hypothesized that there has been a recent regional-level displacement of salt marshes by mangroves. We classified Landsat-5 Thematic Mapper images using artificial neural networks to quantify black mangrove (Avicennia germinans) expansion and salt marsh (Spartina alterniflora and other grass and forb species) loss over 20 years across the entire Texas coast. Between 1990 and 2010, mangrove area grew by 16.1 km(2), a 74% increase. Concurrently, salt marsh area decreased by 77.8 km(2), a 24% net loss. Only 6% of that loss was attributable to mangrove expansion; most salt marsh was lost due to conversion to tidal flats or water, likely a result of relative sea level rise. Our research confirmed that mangroves are expanding and, in some instances, displacing salt marshes at certain locations. However, this shift is not widespread when analyzed at a larger, regional level. Rather, local, relative sea level rise was indirectly implicated as another important driver causing regional-level salt marsh loss. Climate change is expected to accelerate both sea level rise and mangrove expansion; these mechanisms are likely to interact synergistically and contribute to salt marsh loss.

Identifying the impact of the built environment on flood damage in Texas.

Floods continue to pose the greatest threat to the property and safety of human communities among all natural hazards in the United States. This study examines the relationship between the built environment and flood impacts in Texas, which consistently sustains the most damage from flooding of any other state in the country. Specifically, we calculate property damage resulting from 423 flood events between 1997 and 2001 at the county level. We identify the effect of several built environment measures, including wetland alteration, impervious surface, and dams on reported property damage while controlling for biophysical and socio-economic characteristics. Statistical results suggest that naturally occurring wetlands play a particularly important role in mitigating flood damage. These findings provide guidance to planners and flood managers on how to alleviate most effectively the costly impacts of foods at the community level.

Social vulnerability and the natural and built environment: a model of flood casualties in Texas.

Studies on the impacts of hurricanes, tropical storms, and tornados indicate that poor communities of colour suffer disproportionately in human death and injury.(2) Few quantitative studies have been conducted on the degree to which flood events affect socially vulnerable populations. We address this research void by analysing 832 countywide flood events in Texas from 1997-2001. Specifically, we examine whether geographic localities characterised by high percentages of socially vulnerable populations experience significantly more casualties due to flood events, adjusting for characteristics of the natural and built environment. Zero-inflated negative binomial regression models indicate that the odds of a flood casualty increase with the level of precipitation on the day of a flood event, flood duration, property damage caused by the flood, population density, and the presence of socially vulnerable populations. Odds decrease with the number of dams, the level of precipitation on the day before a recorded flood event, and the extent to which localities have enacted flood mitigation strategies. The study concludes with comments on hazard-resilient communities and protection of casualty-prone populations.

Identifying potential conflict associated with oil and gas exploration in Texas state coastal waters: A multicriteria spatial analysis.

Recent interest in expanding offshore oil production within waters of the United States has been met with opposition by groups concerned with recreational, environmental, and aesthetic values associated with the coastal zone. Although the proposition of new oil platforms off the coast has generated conflict over how coastal resources should be utilized, little research has been conducted on where these user conflicts might be most intense and which sites might be most suitable for locating oil production facilities in light of the multiple, and often times, competing interests. In this article, we develop a multiple-criteria spatial decision support tool that identifies the potential degree of conflict associated with oil and gas production activities for existing lease tracts in the coastal margin of Texas. We use geographic information systems to measure and map a range of potentially competing representative values impacted by establishing energy extraction infrastructure and then spatially identify which leased tracts are the least contentious sites for oil and gas production in Texas state waters. Visual and statistical results indicate that oil and gas lease blocks within the study area vary in their potential to generate conflict among multiple stakeholders.

Evaluating ecosystem management capabilities at the local level in Florida: identifying policy gaps using geographic information systems.

Because ecosystem approaches to management adhere to ecological systems rather than human-defined boundaries, collaboration across jurisdiction, agencies, and land ownership is often necessary to achieve effective management of transboundary resources. Local natural resource and land use planners increasingly recognize that while ecosystem management requires looking beyond specific jurisdictions and focusing on broad spatial scales, the approach will partly be implemented at the local level with the coordination of local policies across larger landscapes. This article evaluates the collective capabilities of local jurisdictions to manage large transboundary ecological systems in Florida. Specifically, it combines plan evaluation with geographic information systems (GIS) techniques to map, measure, and analyze the existing mosaic of management across selected ecosystems in the southern portion of the State. Visual and statistical results indicate significant gaps in the management framework of southern Florida that, if filled, could achieve a greater level of consistency and more complete coverage of ecosystem management policies. Based on the spatial distribution of 58 ecosystem management indicators, notable gaps persist in the southwest coast, southeast coast, and central Everglades ecosystems, particularly for wildlife corridors and collaboration with neighboring jurisdictions. We also test for spatial autocorrelation of ecosystem planning scores and find that local jurisdictions with strong ecosystem management capabilities tend to cluster within specific ecosystems. Based on the findings, we make recommendations on how and where local plans can be strengthened to more effectively attain the objectives of ecosystem approaches to management.

Examining localized patterns of air quality perception in Texas: a spatial and statistical analysis.

Environmental and human health issues associated with outdoor air pollution, such as ozone, sulfur dioxide, and other pollutants in metropolitan regions, are an area of growing concern for both policy officials and the general public. Increasing attention from the news media, new health data, and public debate over the effectiveness of clean air regulations have raised the importance of air quality in the public consciousness. While public perceptions of air quality have been studied thoroughly dating back to the 1960s, little empirical research has been conducted to explain the spatial aspects of these perceptions, particularly at the local level. Although recent studies suggest characteristics of local setting are important in shaping perceptions of air quality, the roles of proximity, neighborhood characteristics, and location have not been clarified. This study seeks to improve understanding of the major factors shaping public perceptions of air quality by examining the spatial pattern of local risk perception, the role of socioeconomic characteristics in forming these perceptions, and the relationship between perceived and scientifically measured air pollution. First, we map the spatial pattern of local air quality perceptions using Geographic Information Systems (GIS) across the Dallas and Houston metropolitan areas. Next, we explain these perceptions through local contextual factors using both bivariate correlations and multivariate regression analysis. Results indicate that perceptions of air quality in the study areas are not significantly correlated with air quality based on readings of air monitoring stations. Instead, perceptions appear to be influenced by setting (urban vs. rural), state identification, access to information, and socioeconomic characteristics such as age, race, and political identification. We discuss the implications of the findings and provide direction on how further research can provide a deeper understanding of the local contextual factors influencing public perceptions.

Conflict on the coast: using geographic information systems to map potential environmental disputes in Matagorda Bay, Texas.

The sustainable management of coastal natural resources inevitably involves identifying stakeholder conflicts and developing planning processes that prevent these conflicts from becoming intractable disputes. This study links environmental conflict to specific areas within a large ecological system. Specifically, we use Geographic Information Systems (GIS) to map potentially competing stakeholder values associated with establishing protected areas in Matagorda Bay, Texas. By overlaying multiple values associated with a range of stakeholders across space, we are able to identify hotspots of potential conflict as well as areas of opportunity for maximizing joint gains. Mapping stakeholder conflict is an approach to proactively locate potential controversy in response to a specific environmental management proposal and guide decision makers in crafting planning processes that mitigate the possibility of intractable disputes and facilitate the implementation of sustainable coastal policies. Results indicate that under different management scenarios, protected area proposals will generate more conflict in specific areas. Most notably, regulated uses would produce the greatest degree of conflict on or near shore, particularly at the mouth of the Colorado River. Additionally, of all the management scenarios evaluated, the prohibition of coastal structural development would generate the overall highest level of conflict within the Bay. Based on the results, we discuss the policy implications for environmental managers and provide guidance for future research on location-based conflict management within the coastal margin.