Reconstruction of an 8,000-year record of typhoons in the Pearl River estuary, China

Abstract

An 8,000-year record of typhoons in the Pearl River Estuary is reconstructed through the study of offshore boreholes, beach-dune barriers, historical record and instrumental documentation. In 5 offshore boreholes, a maximum of 17 siliciclastic-dominated storm beds and/or shell-dominated storm beds was identified since about 8,000 calendar years BP. Holocene beach-dune barriers in the vicinity of the estuary were used to study the distribution of landfalling typhoons assisted by radiocarbon and archaeological ages. The pattern found is consistent with multiple typhoons making landfall. Historical record for the period AD 700-1883 has revealed 161 typhoons with reported damage out of which the typhoons of AD 957, 1245, 1862 and 1874 were the most disastrous. During the Little Ice Age, the frequency of typhoons was found to decrease. Only three typhoons in the instrumental documentation period from AD 1884-2000 exceeded the Saffir-Simpson hurricane intensity scale of 3. The frequency of typhoons with paths falling within the South China Sea was found to decrease and increase during El Niňo years and La Niňa years respectively. Since the mid-1970s, the frequency of typhoons in the South China Sea was found to show a decline probably due to a northerly shift of typhoon paths during El Niňo years. However, whether this shift is the result of climate change or natural multidecadal oscillations will require further investigation. Instrumental documentation is concluded to provide the best record of typhoons followed by historical record, beach-dune barriers and offshore boreholes. This is attributed to the inadequate sensitivity of radiocarbon and archaeological ages in distinguishing typhoons and the discontinuous sedimentary record provided by beach-dune barriers and offshore borehole. The degree of damage by typhoons in the historical record is influenced by subjective interpretation.