| Abstract: | This paper describes the formulation and application of a coupled unsaturated/saturated model framework developed to investigate the impact of mining on catchment water yield and groundwater dynamics. The model conceptualization was implemented in both a finite‐element (SUSCAT) and finite‐difference (WEC‐C) solution scheme and found to give similar results. The model framework simulates a coupled surface‐water and groundwater system in which a physically based solution scheme was used to simulate one‐dimensional movement through the unsaturated zone, and a distributed model was used to simulate two‐dimensional saturated groundwater flow. Each soil column comprises a series of layers, each layer being connected to adjacent cells. Subsurface lateral flow is considered when any cell within a layer develops a saturated thickness. Simulation results presented are based on a catchment in the Darling Range, Western Australia that was progressively mined and subsequently rehabilitated. The results predicted the groundwater system beneath the mine areas to have a peak rise owing to mining of between 2 and 4 m. Six years after mining, and following vegetation rehabilitation, the groundwater rise had reduced to 1 m above simulated unmined levels. The corresponding streamflow increase as a result of mining was estimated to peak at 21 mm/year and declined to 7·4 mm/year eight years after revegetation of the mined areas. The simulated groundwater response and streamflow results derived from both models were found to be consistent with observed data. Copyright © 2002 John Wiley & Sons, Ltd. |
