138 A new concept of karst development based on hydrogeology and geophysics The logs from borehole M11 (Fig. 5) are of particular interest because a large cavity encountered between 86.3 and 88.4 m depth results in a significant enlargement of the borehole diameter. In the open-hole section, the temperature log shows two variations at 74 m and 95 m, corresponding to cooler water inflows, but no anomaly is observed within the cavity between 86.3 and 88.4 m. In contrast, the flow log is disturbed between 86 and 88 m due to the enlarged borehole diameter. Water inflows therefore appear to occur around 90–92 m, within a dolomitized and vuggy level, and also between 72 and 74 m, within another dolomitized interval located below a discontinuity. In borehole M12 (Fig. 6), the logs are affected by the presence of the screen (from 69.9 to 105 m) and by changes in borehole diameter. The temperature log indicates cooler water between 90 and 104 m (13.4 °C). On the flow log, velocity increases at 104 m near the bottom of the screen, an effect attributed to the change in borehole diameter. At the top of the screen, the diameter change also causes a decrease in Figure 5 M11 Flowmeters log with pumping in M11. Figure 6 M12 Flowmeters log with pumping in M12.
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