LOCALIZATION OF UNSTABLE ZONES FOR DRAWING UP A ZERMOS MAP. "GEODYNAMIC" MAPPING METHOD IN THE CALVADOS

THE SOUTH AND WEST SLOPES OF THE SAINT-GATIEN PLATEAU WERE MAPPED BY THE "GEODYNAMIC" METHOD AT THE 1/10000 SCALE WITH A VIEW TO DRAWING UP A MAP OF THE ZONES SUBJECT TO SOIL MOVEMENTS (ZERMOS) AT 1/25000. AFTER EXPLAINING THE REASONS FOR SELECTING THIS REGION, THE AUTHORS STUDY THE EVOLUTION OF THE SLOPES, WHICH FOLLOWS THE "MORPHODYNAMIC" MODEL OR IS THE RESULT OF THREE DYNAMICS: CUTS ORIGINATING FROM CONCENTRATED RUN-OFF, ACTION OF WATERTABLES AND SURFACE CREEPING ASSOCIATED TO THE SLOPE. EACH DYNAMIC ASPECT IS ASSOCIATED TO A COLOUR WHICH CAN BE COMBINED TO TWO OTHERS (RED, BLUE, YELLOW), THUS ENABLING THE ESTABLISHMENT OF ZONES INTEGRATING ALL POSSIBLE COMBINATIONS. HYDROLOGICAL DATA ARE ALSO INCLUDED (STREAMS, SOURCES) TOGETHER WITH MORPHOLOGICAL DETAILS (SHAPE OF VALLEYS, RUPTURE OF SLOPES). THE 1/10000 MAP FORMS THE CONCLUSION OF AN ANALYTICAL PHASE, IT FACILITATES THE DEFINITION AND LOCALIZATION OF THE MODE OF EVOLUTION OF SLOPES ELIMINATING THE NOTION OF RISK.