Cave volume computed on the behaviour of a blowing well
(Tournai basin, W. Belgium)

Francis Massen1, Michiel Dusar2, Walter Loy3 and Noël Vandenberghe3

1.    Laboratoire de Physique, Lycée Classique de Diekirch, L-9233 Diekirch, Grand-Duché de Luxembourg
2.    Geological Survey of Belgium, Jennerstraat 13, B-1000 Brussels, Belgium
3.    K.U. Leuven, Historical Geology, Redingenstraat 16, B-3000 Leuven, Belgium

TERRA NOVA, 10, 131-135, 1998


It is difficult to measure karst volume but important to do so to assess risk of sinkhole formation. Measurements of airflow and atmospheric pressure pattern on a water well in buried karst of the overexploited Tournai hydrogeological basin (Belgium) show that inflow and outflow are highly correlated to atmospheric pressure and the differences of extenal and internal air densities.The volume of natural voids in connection with the well within the vadose zone can best be estimated by a calculation based on outflow under constant atmospheric pressure, whichsuggests a possible cavity volume of 700 000 m3 indicating the likelihood of sinkhole formation.

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04 Feb 1999