A process based assessment of engineered structures on reef islands of the Maldives

Kench, Paul, Parnell, Kevin, and Brander, Rob (2003) A process based assessment of engineered structures on reef islands of the Maldives. In: Coasts and ports Australasian conference 2003. From: Coasts and ports Australasian conference 2003, 9-12 September 2003, Auckland, New Zealand.

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Abstract

This paper examines the use and environmental consequences of engineered structures on reef platform islands in the Maldives. The Maldives comprises 1 500 islands which are mostly low-lying sand cays. These cays are inherently unstable, changing their size, and position on reef platforms in response to short-term and seasonal adjustments in wind, wave and current patterns. Island instability combined with high population densities has resulted in the proliferation of engineered structures to combat erosion and to provide boat access. In many instances introduction of hard engineered structures has exacerbated island erosion and degraded reef productivity. Reasons for the negative environmental consequences are twofold. First, the design, materials used in construction and the mode of construction contravene most standard measures of sound engineering design. Constraining sound design is a total lack of environmental information, particularly wave and current data. Second, structures are often inappropriate with respect to natural coastal processes. This is illustrated by wave and current measurements on Hulhudhoo Island in Baa Atoll. Results show the nearshore process regime is dominated by strong alongshore current gradients. Furthermore, seasonal shifts in monsoon winds produce reversals in wave, current and sediment transport patterns. The unique circulatory nature of coastal processes around islands has a number of implications for use of engineered structures. First, conventional engineering practices resulting from an understanding of onshore/offshore and alongshore processes are not necessarily appropriate. Second, it requires reconsideration of notions of passive erosion and placement loss. Effects of structures that are usually transferred alongshore are contained within the 360o island coastline and act to compound island instability and erosion.

Item ID: 1031
Item Type: Conference Item (UNSPECIFIED)
Keywords: reef islands, Maldives, hydrodynamics, alongshore drift, island stability engineering structures
Date Deposited: 03 Nov 2006
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 100%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960301 Climate Change Adaptation Measures @ 100%
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