Turbidity mechanism of water from a karstic spring: example of the Ain Asserdoune spring (Beni Mellal Atlas, Morocco)

To understand the turbidity phenomenon that occurs during floodwater periods in the water of some karstic aquifers, a study was carried out on the Ain Asserdoune spring in the Beni Mellal Atlas. The application of correlation and spectral analyses to turbidity, rainfall and discharge rate with a daily sampling for three hydrological cycles showed that the Ain Asserdoune turbidity corresponded to the beginning of the unclogging of the karstic conduits affecting the saturated area. The appearance of turbidity during the increased flow rate was due to instability in the chaotic regime that was represented by suspended matter, which was evacuated independent of the discharge rate. This phenomenon only appears in polyphase karst, which is frequently found, and thus must be taken into account when karstic water is used for drinking as it could become unfit for human consumption. (C) 2002 Elsevier Science B.V. All rights reserved.