Predicting the site water balance of a phytocapped landfill using HYDRUS 1D

Abstract

An alternative landfill capping technique called 'Phytocapping' was trialled in Rockhampton, Australia. In this technique, trees were used as 'bio-pumps' and 'rainfall interceptors' and soil cover as the 'storage' of water. The performance of this system was measured based on its ability to minimise water percolation into waste. The percolation rate was modelled using HYDRUS 1D for two main scenarios (with and without vegetation) for the thick and thin caps respectively. Results from the measurements and modelling showed that percolation rates of 16.7 mm/year in thick cover and 23.8 mm/year in thin phytocaps are markedly lower than those expected from a clay cap. Both scenarios point to one direction stating the efficiency of phytocaps in restricting water percolation into the buried waste.