Coastal inundation due to sea level rise in the Pearl River Delta, China.

Abstract

This paper examines the increased potential risk of tidal inundations in the Pearl River delta, China, due to future rises in sea level. The research is based on tidal records of 54 tide gauges distributed across the delta plain, and employs mathematical calculations to predict potential rises of water level in different parts of the delta under a number of flood scenarios. After assessing a 72-year tidal record of Hong Kong and factors such as estuarine backwater effects and long-term geological subsidence,it suggests that a 30 cm rise in relative sea level at the mouth of the estuary is possible by 2030. Based on the prediction and five freshwater discharge scenarios, the potential impacts on water levels across the delta plain are calculated. Three zones are identified as least affected, heavily affected and severely affected. The impacts are also translated into return periods of water level. It is suggested that in a large part of the delta plain, return periods will be shortened and hence will be increasingly vulnerable to tidal inundation. Finally, management implications are discussed along with assessment of the adequacy of the existing tidal flood defences, as well as evaluation of the cost implications if they are to be improved.