Green River Levee Removal and Floodplain Connectivity Evaluation
Author: Levee Removal Evaluation Group
Publisher:
Published: 1998
Total Pages: 201
ISBN-13:
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Author: Levee Removal Evaluation Group
Publisher:
Published: 1998
Total Pages: 201
ISBN-13:
DOWNLOAD EBOOKAuthor:
Publisher:
Published: 1997
Total Pages: 96
ISBN-13:
DOWNLOAD EBOOKAuthor: Committee on Levees and the National Flood Insurance Program Improving Policies and Practices
Publisher: National Academies Press
Published: 2013-08-01
Total Pages: 249
ISBN-13: 0309282918
DOWNLOAD EBOOKThe Federal Emergency Management Agency's (FEMA) Federal Insurance and Mitigation Administration (FIMA) manages the National Flood Insurance Program (NFIP), which is a cornerstone in the U.S. strategy to assist communities to prepare for, mitigate against, and recover from flood disasters. The NFIP was established by Congress with passage of the National Flood Insurance Act in 1968, to help reduce future flood damages through NFIP community floodplain regulation that would control development in flood hazard areas, provide insurance for a premium to property owners, and reduce federal expenditures for disaster assistance. The flood insurance is available only to owners of insurable property located in communities that participate in the NFIP. Currently, the program has 5,555,915 million policies in 21,881 communities3 across the United States. The NFIP defines the one percent annual chance flood (100-year or base flood) floodplain as a Special Flood Hazard Area (SFHA). The SFHA is delineated on FEMA's Flood Insurance Rate Maps (FIRM's) using topographic, meteorologic, hydrologic, and hydraulic information. Property owners with a federally back mortgage within the SFHAs are required to purchase and retain flood insurance, called the mandatory flood insurance purchase requirement (MPR). Levees and floodwalls, hereafter referred to as levees, have been part of flood management in the United States since the late 1700's because they are relatively easy to build and a reasonable infrastructure investment. A levee is a man-made structure, usually an earthen embankment, designed and constructed in accordance with sound engineering practices to contain, control, or divert the flow of water so as to provide protection from temporary flooding. A levee system is a flood protection system which consists of a levee, or levees, and associated structures, such as closure and drainage devices, which are constructed and operated in accordance with sound engineering practices. Recognizing the need for improving the NFIP's treatment of levees, FEMA officials approached the National Research Council's (NRC) Water Science and Technology Board (WSTB) and requested this study. The NRC responded by forming the ad hoc Committee on Levee and the National Flood Insurance Program: Improving Policies and Practices, charged to examine current FEMA treatment of levees within the NFIP and provide advice on how those levee-elated policies and activities could be improved. The study addressed four broad areas, risk analysis, flood insurance, risk reduction, and risk communication, regarding how levees are considered in the NFIP. Specific issues within these areas include current risk analysis and mapping procedures behind accredited and non-accredited levees, flood insurance pricing and the mandatory flood insurance purchase requirement, mitigation options to reduce risk for communities with levees, flood risk communication efforts, and the concept of shared responsibility. The principal conclusions and recommendations are highlighted in this report.
Author:
Publisher:
Published: 1980
Total Pages: 64
ISBN-13:
DOWNLOAD EBOOKAuthor: United States. General Accounting Office
Publisher:
Published: 1995
Total Pages: 84
ISBN-13:
DOWNLOAD EBOOKAuthor: Green River Basin Program (Wash.)
Publisher:
Published: 1986*
Total Pages: 88
ISBN-13:
DOWNLOAD EBOOKAuthor: Timothy Modde
Publisher:
Published: 1998
Total Pages: 68
ISBN-13:
DOWNLOAD EBOOKAuthor: Ashley N. Adams
Publisher:
Published: 2015
Total Pages: 60
ISBN-13:
DOWNLOAD EBOOKLevee vegetation management has been a challenge in King County due to conflicting federal mandates. Since the early 1990s King County has been incorporating bioengineering techniques into levee repairs. These techniques entailed the use of vegetation to not only provide bank stability but to also improve conditions for salmon as required under the Endangered Species Act. However, the U.S. Army Corps of Engineers required the removal of any vegetation over two inches in diameter to remain eligible for federal emergency funding under Public Law 84-99, hypothesizing that it compromised levee stability as well as hindered inspections. While there have been many studies on vegetation's effect on stability in natural systems, less information is available on the effect of vegetation on the structural stability of levees and revetments This research investigates the effect of vegetation on levee structural integrity on the Green River in King County, Washington State. Initially, the investigation set out to compare levees repaired using bioengineering techniques with levees repaired using traditional rock. However, no digital information was available on bioengineered levee projects on the Green River that could be used to develop a study plan. The first project task involved organizing files and documenting the institutional knowledge at King County on the levee projects along the Green River. Fifty-four bioengineered repairs on the Green River were visited and geo-referenced. Based on information gleaned from the data mining and mapping exercises, it became clear that comparisons of stability of bioengineered versus non-bioengineered levees could not be made. As such, a retrospective pilot study was undertaken to directly address the issue of the role of vegetation in levee stability. Using a case control method, 12 documented levee sites that incurred damage during November 2006 flooding were matched with undamaged sites on a one to one basis. Basic land cover type (trees, shrubs, grass, bare ground, impervious surfaces) was delineated through aerial photography taken prior to the flooding and percent cover of each type was calculated from these measurements. Study results reveal the paired differences between percent cover of trees, impervious surfaces, and bare ground were not statistically significantly different between damaged and control sites. However, of the paired sites where trees were present on both the case (damaged site) and the control, the control generally had more tree cover than the case. Shrub cover was statistically higher on damaged sites than on control sites. but it was not possible to determine if shrub cover was native or non-native. Post-hoc power analysis indicates that a much larger sample size of at least 54 matched cases and controls would be needed to determine a more scientifically defensible and statistically robust result for the effect of tree cover on levee damage. The steps taken for the pilot study could be duplicated in any larger study. However, it is unlikely that all damages could be satisfactorily matched with bioengineered sites on the Green River given the number of variables to be considered when matching. The results from this study show the complexity of trying to isolate a single factor contributing to levee stability.
Author: Katia Perini
Publisher: John Wiley & Sons
Published: 2017-02-06
Total Pages: 235
ISBN-13: 111924496X
DOWNLOAD EBOOKUrban Sustainability and River Restoration: Green and Blue Infrastructure considers the integration of green and blue infrastructure in cities as a strategy useful for acting on causes and effects of environmental and ecological issues. River restoration projects are unique opportunities for sustainable development and smart growth of communities, providing multiple environmental, economic, and social benefits.This book analyzes initiatives and actions carried out and developed to improve environmental conditions in cities and better understand the environmental impact of (and in) dense urban areas in the United States and in Europe.