Shoreline Change Caused by Sea Level Rise Over the Next 100 Years –Predictions, Economics, and Policy: Broward County, Florida

Defense Date

11-2012

Document Type

Capstone

Degree Name

M.S. Coastal Zone Management

First Advisor

Kenneth Banks

Second Advisor

Steffen Schmidt

Abstract

Global warming is contributing to sea level rise, which is creating concern for coastal communities. The beaches of Broward County, Florida have been designated as critically eroding and they are a particular topic of concern as published sea level scenarios project a continued rise during the next century. Beach erosion is the result of many factors including rapid coastal development, coastal structures, and sea level rise. In order to compensate for the rapid beach loss, nourishment projects, using offshore sand, have been used in Broward County since 1970, and these have had less erosion effects to neighboring beaches, when compared to other stabilizing methods such as groins. Funding to continue frequent nourishment projects will become more difficult to achieve as the cost of sand increases due to limited offshore compatible resources. Current upland sediment source costs were estimated at $26.75/m3 compared to the previous (1970- 2011) costs of $11.50/m3 using offshore sand sources. Due to limited offshore compatible sand sources, estimates herein have been based on the use of upland sand source for future beach nourishment projects. Upland sand source costs are higher due to greater transportation costs to the beaches of Broward County. In order to estimate sand loss due to future sea level rise projections, Bruun developed an equation to quantify shoreline recession resulting from sea level rise. This (1962) was used to calculate resultant shoreline change. Beach erosion surveys previously conducted along Broward County’s coastline were evaluated to determine historical shoreline and volume change rates. The resulting data were used to project minimum and maximum published sea level rise projections for the years 2030, 2060, and 2100. The costs to mitigate the resultant beach erosion was extrapolated from current costs with a discount rate applied and used to determine future costs of sea level rise-induced erosion. In order to understand the policy impacts of sea level rise along southeast Florida’s coastline, an interview was conducted with local coastal planning managers. Responses indicated that coastal managers are concerned with the impacts of rising sea levels and suggest the use of both hard and soft stabilization structures in order to deal with increased beach erosion. As the cost for nourishment projects increases in Broward County, development regulations including adjusted flood zones for the future impacts will be required in order to reduce the upland pressures on the eroding beach as sea level rises.

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