MODELING AND FORECASTING OF TIME-SERIES - APPLICATION TO THE TEMPORAL EVOLUTION OF MINING EXHAUST IN THE LORRAIN FERRIFEROUS BASIN

A systematic study of the monthly data of mining water exhaust in the Lorrain mining basin has been performed on 24 mines during the period 1945-1985. The study shows the existence of two types of mines: stationary mines and non stationary mines. Such heterogeneity in space is related to the geological, topographical and structural conditions. A general model relating the exhaust (Q(t)) proportioned by the cumulative extraction of mineral (S(t)) to the effective rainfall (E(t)) is proposed. This model can be written in the form of a convolution equation: Q(t)/S(t)beta = C + phi(tau)E(t-tau) + epsilon(t) (1) The exponent beta depends on the exploitation methods, local geological conditions and the thickness of the exploited layer (beta = 0 for the stationary and 0 < beta less-than-or-equal-to 1 for the non-stationary mines). The model may be used to evaluate the water resources for an under-exploited basin or for an exploited basin such as those of the Lorrain mining basin.