Mine flooding is a serious problem in the Enugu Coal Mines and has led to the abandonment of two of the four mines. About 1800 m3 of water is pumped out daily from the mines into the nearby streams. The source of this enormous volume of water has been established based on the hydrodynamics and hydrology of the area. It is shown that although two prolific aquifers—an unconfined and a confined system—overlie the mines, the mine water is derived principally from the unconfined aquifer. The pathway of flow is, however, provided by the numerous fractures connecting the two aquifers and the mine tunnel.
The major hydrochemical activity resulting in pollution of the mine water occurs within the sumps in the floor of the longwalls. These sumps act as oxidation chambers where groundwater from the fractures is mixed and subsequently reacted with sulfur-rich solutes released by coal mining.
Contrary to general belief, the mine drainage has not seriously degraded the chemistry of receiving streams. The pH, electric conductivity and, thus, the dissolved ions were increased less than 10% of the values in the unaffected region.
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- Bear, J., 1972, Dynamics of fluid flow in porous media: New York, Elsevier.Google Scholar
- Bear, J., 1980, Hydraulics of groundwater: Israel, McGraw-Hill.Google Scholar
- Benkhelil, J., 1988, Structure and geodynamic evolution of the intercontinental Benue Trough, Nigeria: Bull. Centre Rech. Explor-Prod. Elf-Aquitaine, v. 12, p. 29–128.Google Scholar
- de Swardt, A. M. J., and O. P. Casey, 1961, The coal resources of Nigeria: Geol. Surv. Nig., Bull. no. 28.Google Scholar
- Egboka, B. C. E., and K. O. Uma, 1985, Acid mine drainage problems in the Enugu Coal Mines of Anambra State, Nigeria: Proc. Int. Mine Water Congress, Granada-Spain, v. 1, p. 1–11.Google Scholar
- Egboka, B. C. E., and K. O. Uma, 1986, Comparative analysis of transmissivity and hydraulic conductivity values from the Ajali aquifer system of Nigeria: J. Hydrol., v. 83, p. 185–196.Google Scholar
- Ezeanyim, B. N., 1988, Hydrogeology of Enugu and environs: Unpublished MSc thesis. University of Nigeria, Nsukka, Nigeria.Google Scholar
- Freeze, R. A., and J. A. Cherry, 1979, Groundwater: Englewood Cliffs, NJ, Prentice-Hall.Google Scholar
- Freeze, R. A., and P. A. Witherspoon, 1966, Theoretical analysis of regional groundwater flow: 1. Analytical and numerical solutions to the mathematical model: Water Resour. Res., v. 1, p. 641–656.Google Scholar
- Logan, J., 1964, Estimating transmissivity from routine production tests of wells: Groundwater, v. 2, p. 35–37.Google Scholar
- Lohman, S. W., 1972, Groundwater hydraulics: U.S. Geol. Surv. Prof. Paper 708.Google Scholar
- Llyod, J. W., and J. A. Heathcote, 1985, Natural and inorganic hydrochemistry in relation to groundwater: Oxford, U.K., Clarendon Press.Google Scholar
- Okagbue, C. O., and V. O. Onuoha, 1886, Environmental problems related to coal mining in Enugu area: Proceedings, 1st Annual Conference of the Nigerian Water and Sanitation Association, Lagos, p. 233–256.Google Scholar
- Piper, A. M., 1944, A graphic procedure in the geochemical interpretation of water analyses: Trans. Am. Geophys. Union, v. 25, p. 914–923.Google Scholar
- Toth, J., 1963, A theoretical analysis of groundwater flow in small drainage basins: J. Geophys. Res., v. 68, p. 4795–4812.Google Scholar
- Uma, K. O., and B. C. E. Egboka, 1988, Three cheap methods of determining groundwater recharge in the rain forest belt of Nigeria,in I. Simmers, ed., Estimation of natural groundwater recharge: Dordrecht, D. Reidel, p. 435–447.Google Scholar