Preliminary numerical study on groundwater system at the Hong Kong International Airport

Abstract

The Hong Kong International Airport was built on a man-made island. The groundwater head of the deep basal sand and gravel aquifer remains high several years after the land reclamation. The heads in different aquifers indicate an upward groundwater flow. The aim of this study is to understand the abnormally high pore water pressure in the basal aquifer. The most plausible explanation for the abnormal pressure distribution is that the groundwater flow below the airport is probably a part of the regional groundwater flow system of the Lantau Island. The airport is located at the upward discharge zone of the Lantau groundwater flow system. Based on groundwater level measurement in the airport site, a multi-aquifer model is used to simulate groundwater flow in the regional flow system. Simulation results illustrate that the high pore pressure in the basal aquifer can be generated by the regional flow system in the Lantau Island and the pore pressure is strongly affected by the seasonal variation in rainfall recharge and the hydraulic conductivity of the alluvial clay.