Sediment Budget Analysis for Sustainable Shoreline Protection and Management

摘要

An intensive field investigation on the application of sediment budget analysis for sustainable shoreline protection and management was carried out at the updrift and downdrift shoreline adjoining Qua-Iboe River estuary, south-east coast of Nigeria. The study employed variations in beach volumes within a 500m-littoral cell of sediment compartment, based on daily beach profile surveys, measured over a neap-spring tidal cycle at the shoreline, as the fundamental tool for the analysis. A comparative analysis of the results of short- term beach profile morphologic changes at the shoreline depicted the updrift beach as the sediment source and the downdrift counterpart as the sink. A sediment budget deficit of 1498 m3 per day with an annual sediment budget of 546770 m3 estimated for beach nourishment, due to erosion traced to storm surge incident at the shoreline in 2011, and was recorded at the updrift beach. However, result of the downdrift shoreline which revealed a budget surplus of 11190 m3 per day with an annual budget estimate of 4084350m3 was attributed to massive deposit of sediment at the beach. The estimated volumes of sediment in this report were calculated based on a new sediment budget equation: -[( [ ΣA(1,2,…)] –[ ΣE(1,2,…) ]) - (Rv x L)]t=Residual. One of the benefits of the new equation is the inclusion of sustainability factor (Rv x L) for efficient and sustainable shoreline protection and management.