Section 404 permitting in coastal Texas from 1996 - 2003: patterns and effects on streamflow

This study explores the spatial-temporal patterns of Section 404 permitting program under the Clean Water Act and examines its impact on mean and peak annual streamflow. The study area consists of 47 sub-basins that are delineated based on USGS streamflow gauges. These sub-basins span from the southern portion of coastal Texas to the easternmost portion of coastal Texas. Descriptive, spatial and spatial-temporal statistical methods are used to explore patterns in Section 404 permitting between 1996 and 2003. The effects of Section 404 permit types on mean and peak annual streamflow over the same 8 year period are also statistically modeled with a host of other relevant control variables. Exploratory analyses of Section 404 permits demonstrated characteristics that were indicative of suburban and, to a larger extent, exurban development. Explanatory analyses of the effects of Section 404 permitting on mean and peak streamflow showed that Section 404 permits increase both measures. These increases were minimal on a per-permit basis but have the ability to accumulate over time and result in much larger increases. Section 404 permits also displayed an ordered effect based on the permit type. Permit types that represent larger impacts had larger effects. The effects of permits of streamflow followed a descending pattern of Individual permits, Letters of Permission, Nationwide permits, and General permits. This “type of permit impact” supports the use of this measure as an indicator of wetland impact and loss and corroborates previous studies that have incorporated this measure

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 km2, a 74% increase. Concurrently, salt marsh area decreased by 77.8 km2, 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.The open access fee for this work was funded through the Texas A&M University Open Access to Knowledge (OAK) Fund

A spatial-temporal analysis of section 404 wetland permitting in Texas and Florida: Thirteen years of impact along the coast

Over the past 200 years, an estimated 53% (about 47 million ha) of the original wetlands in the conterminous United States have been lost, mainly as a result of various human activities. Despite the importance of wetlands (particularly along the coast), and a longstanding federal policy framework meant to protect their integrity, the cumulative impact on these natural systems over large areas is poorly understood. We address this lack of research by mapping and conducting descriptive spatial analyses of federal wetland alteration permits (pursuant to section 404 of the Clean Water Act) across 85 watersheds in Florida and coastal Texas from 1991 to 2003. Results show that more than half of the permits issued in both states (60%) fell under the Nationwide permitting category. Permits issued in Texas were typically located outside of urban areas (78%) and outside 100-year floodplains (61%). More than half of permits issued in Florida were within urban areas (57%) and outside of 100-year floodplains (51%). The most affected wetlands types were estuarine in Texas (47%) and palustrine in Florida (55%). We expect that an additional outcome of this work will be an increased awareness of the cumulative depletion of wetlands and loss of ecological services in these urbanized areas, perhaps leading to increased conservation efforts

Uncertainty in Flood Mitigation Practices: Assessing the Economic Benefits of Property Acquisition and Elevation in Flood-Prone Communities

Adopting effective flood mitigation practices for repetitive flood events in the United States continues to play a prominent role in preventing future damage and fostering resilience to residential flooding. Two common mitigation practices for reducing residential flood risk consist of raising an existing structure to or above base flood elevation (BFE) and acquiring chronically damaged properties in flood prone areas and restoring them back to serve their natural functions as green open spaces. However, due to data accuracy limitations, decision makers are faced with the challenge of identifying the financially optimal approach to implementing mitigation measures. We address this problem through the following research questions: What does the optimal allocation of flood mitigation resources look like under data uncertainty, and what are the optimal methods to combining mitigation measures with consideration for the best economic benefits? Using a robust decision making (RDM) approach, the effects of uncertainty in property values, construction and demolition costs, and policy implementation options such as structure selection and budget allocation were measured. Our results indicate that the amount budgeted for mitigation and how those funds are allocated directly influence the selection of the most economically viable mitigation practices. Our research also contributes to the growing need for evaluating specific flood mitigation strategies

Planning at the urban fringe: an examination of the factors influencing nonconforming development patterns in southern Florida

Although the components of plan quality are well defined, little empirical research has been conducted to understand the degree to which policies are being implemented after plan adoption and the factors contributing to the variation in plan implementation. The authors test the efficacy of land-use planning and plan implementation in Florida by measuring the degree to which wetland development over a ten-year period conforms to the original design of adopted comprehensive plans. First, they spatially identify concentrated areas of wetland alteration permits and compare these locations with the adopted future land-use maps for county and city jurisdictions in the southern portion of the state. Second, they examine the major factors influencing nonconforming development patterns across the study area. Results indicate a well-defined spatial pattern of nonconforming wetland development and isolate specific socioeconomic, demographic, and geographic variables impacting these deviations from the original spatial intent of local plans.

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

Modeling national flood insurance policy holding at the county scale in Florida, 1999-2005

We analyze household flood insurance purchases in Florida from 1999 to 2005, and the extent to which household insurance purchases correspond with flood mitigation activities by local governments involved in the Federal Emergency Management Agency's (FEMA) Community Rating System (CRS). Regression results indicate that household flood insurance purchases correlate strongly with local government mitigation activities, adjusting for hazard experience, hazard proximity, and community demography. Policy implications of this observed relationship are discussed, assuming four temporal order and floodplain development scenarios, with particular attention to the congruence of outcomes relative to policy objectives.National Flood Insurance Program Florida Flood mitigation Community rating system Flood risk Moral hazard

Confusion matrices depicting the accuracy of coastal Texas land cover classification in 2010 and 1990.

<p>Confusion matrices depicting the accuracy of coastal Texas land cover classification in 2010 and 1990.</p

The minimum recorded temperature (°C) at weather stations along the Texas coast, with the number of days with minimum temperatures below -6.7°C in parentheses.

<p>- indicates that data were not available. Weather data were obtained from the NOAA National Climatic Data Center (<a href="http://www.ncdc.noaa.gov/" target="_blank">http://www.ncdc.noaa.gov/</a>).</p><p>The minimum recorded temperature (°C) at weather stations along the Texas coast, with the number of days with minimum temperatures below -6.7°C in parentheses.</p