Catchment hydrology
Understanding catchment hydrology is key to understanding water in the Copperbelt. This understanding is critical to efficient production.
DHI has developed a series of physics-based catchment hydrology models at this mine site using MIKE SHE. Physics-based models provide clear insight into the complex relationships and feedbacks between rainfall, infiltration, evapotranspiration, groundwater flow, runoff and stream flow.
The water balance is driven by the physical characteristics of the hydrology, the geology and the mine. Simple, lumped conceptual models that ignore the spatial and temporal relationships of these components are at serious risk of failing.
The MIKE SHE models of the catchment and the mine areas are able to capture the dynamics and spatial distribution of the groundwater recharge, by calculating actual evapotranspiration from available water and measured rainfall. This eliminates the need to make questionable guesses about groundwater recharge – the most critical boundary for a groundwater model. The integrated groundwater-surface water models provide a sound basis for the specialised, detailed groundwater dewatering models, as well as support decisions related to disposal of dewatering water, stream diversions and flood control.
Pit dewatering
The Copperbelt is notorious for very wet mines. High groundwater levels in the mine floor can hinder production and significantly increase blasting costs. Efficient dewatering is critical to maintaining production volumes and minimising costs. Yet, the vagaries of rural Central Africa and the complexity of the deposits mean that drilling dewatering wells is both expensive and time-consuming. Planning must be early, yet remain flexible. A detailed, accurate groundwater model is an important tool for mine managers in this process. DHI has developed a series of detailed groundwater models at this mine site using FEFLOW.
The FEFLOW dewatering models at this mine are being used in operations to plan for and locate new dewatering wells, as well as optimise pumping rates at existing wells. The subsurface geology is extracted directly from MineSight™ and Leapfrog™ geologic models delivered by the exploration group.