Using a multiple water balance approach to estimate recharge for the optimum mine, Mpumalanga

[摘要] This dissertation focused on using multiple water balance recharge methods withinrehabilitated opencast mines at the Optimum Coal Mine, Mpumalanga,for the aimthat a combination of water balance methods will yield more conclusive rechargefrom rainfall values within spoil material. It is known that different recharge methodsyield very different results concerning recharge. New recharge methods wereimplemented based on the data received from the mine and compared to therecharge method already developed and proven to work.In the pursuit to solve the complicated issue of calculating recharge from rainfall, fournewly formulated methods were produced, called the Rainfall Infiltrated Volume,Stage Curve Volume, Dry and Wet Calculations and Recharge from Stage CurveVolume. These methods were compared to wellknownrecharge methods whichincluded the Saturated Volume Fluctuation, Cumulative Rainfall Departure andWater Table Fluctuation methods over a fiveyearperiod. These methods, combined,narrowed the range between the minimum and maximum recharge values, usuallyestimated for the study area, and in the process provided a better understanding ofthe water management systems in this area.Pit Volume Calculations yielded a 25% void space for spoils, which were used in therecharge calculations. Each method yielded a minimum and maximum rechargevalue from rainfall, but not all of them produced the results expected from the area.The Zevenfontein opencast rehabilitated pit produced very accurate and believablerecharge from rainfall at 18�?0% for the new recharge methods and 15�?7% for theknown recharge methods. The Optimus opencast rehabilitated pit had numerousproblems, but in the end also produced believable results at 25�?0% for the newrecharge methods and 15�?0% for the known recharge methods.Thus, it was concluded that a combination of recharge methods yielded moreconclusive recharge values.

[发布机构] University of the Free State