The Blumau Aquifer Southeastern Austria

This complex has been intensively studied (Andrews et al., 1984). Drastic discontinuities were reported for groundwater properties passing from the phreatic part of the aquifer to the confined part. The transition is observed between two wells, about 400 m apart. For example, 14C drops from 114 pmc to 48pmc, tritium drops from 49 TU to 0.8 TU, d18O drops from —8.6% to —9.3%, and bicarbonate rises from 100mg/l to 320mg/l.

Fig. 11.28 14C values (pmc) in wells of the Sokoto basin, northern Nigeria. The arrow denotes the orginally suggested groundwater flow direction. The phreatic aquifer (A) coincides with the rock outcrops (stippled) and has high 14C values. An abrupt drop in 14C values is observed in the adjacent confined section of the system (B). (Data from Geyh and Wirth, 1980.)

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