Matrix and fissure water movement through unsaturated calcareous sandstone

Evaluation of pollution endangering groundwater resources beneath fractured sediments may be achieved by estimating the transport rates and recharge amounts of both the matrix and the fissure components. This study examines the transport of water by matrix and fissure flow in the unsaturated zone using environmental tritium as a natural tracer. A 35-year record of tritium concentration along 40 m calcareous sandstone column was reconstructed. It was found that on the average, 40 mm yr¹ (8% of the yearly rain) percolated downward through the matrix pores at a velocity of 1.1 m yr¹. An additional amount of more than 20 mm yr¹ (more 4% of the rains) percolated rapidly through fissure network. These field data fit and support the model proposed by Wang and Narashimham (1985) that the bulk of the water movement under unsaturated conditions occurs through interconnected pores in the matrix.