Interdisciplinary Planning of Nonstructural Flood Hazard Mitigation
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Interdisciplinary Planning of Nonstructural Flood Hazard Mitigation B. D. Hayes, P.E., A.M.ASCE1 Abstract: An interdisciplinary team consisting of representatives from state government and academia has developed an innovative flood risk management plan that combines a large-scale ‘‘nonstructural’’ hazard mitigation plan with portions of a federally authorized plan previously developed by the U.S. Army Corps of Engineers. Separate elements of the federally authorized plan were considered for inclusion in the alternative plan based on the estimates of each element’s marginal benefit/cost ratio, potential environmental impacts, and level of consistency with current policy. The plan involves retrofitting approximately 1,500 residential and nonresidential structures in the 100-year floodplain and requires development of a structure-by-structure flood proofing benefit/cost analysis computer program. At less than half the cost, the alternative plan achieves flood risk management goals in a significantly more cost-effective manner for an environmentally sensitive area. DOI: 10.1061/͑ASCE͒0733-9496͑2004͒130:1͑15͒ CE Database subject headings: Flood damage; Remedial action; Risk management; U.S. Corps of Engineers. Introduction Institute ͑UHI͒ at the University of Massachusetts and the five departments of EOEA met weekly during the early development In 1989, the New England Division of the U.S. Army Corps of process. The participants came from the Metropolitan District Engineers completed a flood damage reduction plan for a region Commission ͑MDC͒, which assumed sponsorship for the Corps’ north of Boston, including portions of Saugus, Lynn, Revere, and project in 1987; the Department of Environmental Management Malden. The Corps’ floodgate plan relies heavily on flood control ͑DEM͒, which has primary responsibility for managing flood haz- structures, most notably, a 1,290-ft-long ͑393-m-long͒ floodgate ards in the state; the Department of Environmental Protection across the mouth of the Saugus River as well as 3.5 mi ͑5.6 km͒ ͑DEP͒, which is responsible for administering environmental of new seawalls and dikes ͑USACE 1989͒. Because of policy, regulations; Massachusetts Coastal Zone Management ͑MCZM͒; environmental, and financial issues, the Executive Office of En- and the Department of Fisheries, Wildlife and Environmental Law vironmental Affairs ͑EOEA͒ of Massachusetts decided to explore Enforcement ͑DFWELE͒. The participation of DEP, MCZM, and whether an alternative plan using a wider variety of techniques DFWELE was of key importance because of their roles in the including non-structural approaches, such as elevating or remov- regulatory and permitting process as well as their ability to articu- ing structures in flood-prone areas, could be developed. Develop- late environmental concerns. MCZM is a state policy develop- ment of an alternative plan required several innovations in flood ment agency that advises the Secretary of EOEA on coastal policy risk management planning. First, an interdisciplinary approach and long-range planning and has veto power over federal actions was taken that involved the cooperative efforts of individuals in the coastal zone. A representative from the Division of Marine from various state environmental agencies and academia. Second, Fisheries ͑DMF͒, a branch of DFWELE, also participated in the the plan was reviewed by an external academic review commit- development process. tee. Third, less established methods of reducing potential damages Together, the individual representatives of the five departments through ‘‘nonstructural’’ hazard mitigation were used. Finally, of EOEA provided valuable insight into the process. Besides the benefit/cost analysis for the plan as a whole required the devel- expertise each of these representatives brought when completing opment of a computer program to establish flood-proofing recom- the many tasks associated with the project, the group provided mendations on a structure-by-structure basis for a large inventory advice and direction for the developing plan. As a result, current of structures in the floodplain. trends toward fiscal responsibility via cost-sharing agreements The interdisciplinary approach taken in this work involved with municipalities were incorporated into the project. Similarly, government directly in the planning process for an alternative the goal of avoiding variances in the permitting process is incor- plan. A team consisting of individuals from the Urban Harbors porated directly into the development process. In addition, peer review was sought for the plan. The Academic Review Commit- 1PhD, Senior Project Manager, Sadat Associates, Inc., 1545 Lamber- tee provided comments on the plan both during the conceptual ton Road, PO Box 4129, Trenton, NJ 08610. E-mail: [email protected] phase and later. Note. Discussion open until June 1, 2004. Separate discussions must Within the study area are 1,660 acres ͑672 ha͒ of productive be submitted for individual papers. To extend the closing date by one salt marsh that provide diverse habitat critical to migratory water- month, a written request must be filed with the ASCE Managing Editor. ͑ ͒ The manuscript for this paper was submitted for review and possible fowl and marine life Fig. 1 . The commonwealth’s interest in a publication on January 30, 1997; approved on February 24, 2003. This flood hazard mitigation plan that relies more extensively on non- paper is part of the Journal of Water Resources Planning and Manage- structural techniques in this area was largely for concerns regard- ment, Vol. 130, No. 1, January 1, 2004. ©ASCE, ISSN 0733-9496/ ing impacts on the estuary. Nonstructural approaches minimize 2004/1-15–25/$18.00. impacts on environmentally sensitive areas and reduce the likeli- JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT © ASCE / JANUARY/FEBRUARY 2004 / 15 Fig. 1. Study area hood of further encroachment on areas such as the estuary of the associated with sea level rise has not been consistent nor has a Saugus and Pines Rivers. Potential long-term environmental im- comprehensive national policy been developed ͑Platt et al. 1992͒. pacts on the estuary are difficult to evaluate because of uncertain- Growing trends in coastal flood risk management on national, ties related to the rate of sea level rise and the lengthy 100-year state, and local levels currently favor softer approaches such as life expectancy of the Corps’ floodgate plan. In light of these beach renourishment. The NRC has stated that plans that can be uncertainties, nonstructural techniques and their associated envi- expected to perform well under existing and future uncertain con- ronmental conservativeness are preferable for this exceptional and ditions should be preferred ͑NRC 1987͒. vulnerable ecological resource. The 100-year floodplain in the study area is heavily developed Flood risk management in an urban coastal setting is by nature and includes approximately 2,000 residential structures and 585 a complex, multiobjective problem. Efforts to minimize natural nonresidential structures. The study area experiences frequent hazards to the population and potential damage to property and coastal storms and some flooding almost yearly. The storm of infrastructure are constrained by a variety of factors. Significant record occurred in February of 1978. Corps’ estimates of total engineering resources are required for analysis of the hydrologic direct and indirect damages and costs for all of Lynn and Revere forces that drive the problem and for the design, analysis, and including parts not in the study area were $52,402,500 in 1994 comparison of potential solutions. Management of coastal flood dollars ͑USACE 1979; Hayes 1995͒. Saugus and Malden experi- risks is similar to flood risks in rivers, excepting two major fac- enced relatively little damage because of their lack of exposure to tors. First, coastal wave action adds complexity to the analysis of direct wave and wind effects from the ocean. potential damages. Second, a more complicating factor is the issue of sea level rise. A coastal flood plan must address an in- creasingly discouraging scenario of increased frequency and se- Previous Efforts by Corps of Engineers verity of flooding in future years because of sea level rise. Unfor- tunately, the actual future rate of relative sea level rise is highly In 1985, the Corps of Engineers was asked to develop a regional uncertain. The historic rate in Massachusetts has been 0.3 m every flood damage reduction plan by officials of the state and the four 100 years; however, estimates of an increase as high as1mbythe communities in the study area ͑USACE 1989͒. Three alternative year 2075 are accepted by many experts ͑USACE 1989͒. Federal plans were formulated. Two of these plans relied heavily on ar- response to the issue of shoreline recession and coastal erosion mament. Option 1 relied on armament of both the seacoast and 16 / JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT © ASCE / JANUARY/FEBRUARY 2004 borders of the estuary. Option 3 relied on armament of only the year during the years leading up to the end of the 35-year life seacoast combined with the construction of a floodgate across the span͒ do not appear to have been reviewed with regard to envi- Saugus River. These two plans ͑Options 1 and 3͒ had comparable ronmental impact nor the ability to receive permits or variances costs and benefits and received extensive analysis. The third al- associated with increased floodgate closure duration and fre- ternative ͑Option 2͒, consisting purely of nonstructural