Investigate the possible reduction of mine water ingress by introducing tree plantations

Abstract

Continuous influx of groundwater into underground mine workings requires significant financial investment in terms of high pumping costs associated with the pumping of large volumes of water ingress, that could eventually render a mine unprofitable. An innovative alternative to pumping methods with the purpose to reduce water volumes, is the establishment of deep rooted, high water-use vegetation covers to act as “artificial pumps”. Hydraulic control is one of the leading applications of plant-based strategies for remediating and managing groundwater systems by introducing plantations in selected areas with high ingress potential. This study investigated the impact of plantation introduction on the reduction of effective groundwater recharge. A temperature-based field model was formulated to determine daily Evapotranspiration (ET) from measured and observed leaf and air temperature. Results were compared to the FAO Penman-Monteith reference crop ET model and the Shuttleworth-Wallace model in order to validate the predictions of the field model. The developed field model was then used to predict monthly ET values for the Cooke 4 study area (Gemsbokfontein West compartment) to determine the possible reduction of pumping volume. The area selected for the proposed plantation was selected based on groundwater levels and the agricultural potential. A water balance for the study area was developed through the use of the Saturated Volume Fluctuation (SVF) method and inflows to the study area were modelled as head dependent through the use of a conductance term