Naden, P.S., Calver, A., Reed, D.W., Reynard, N.S. 1993. Rainfall-induced landslides: a hydrological perspective. Report to CEC, EPOCH Contract 0029, November 1993, 63 pp.
This document presents the results of the Institute of Hydrology (IH) contribution to CEC EPOCH Contract 0029 on Rainfall-induced landslides in the Mediterranean mountainous zone of Europe: the preparation of hazard maps in selected areas of Italy, Spain and Greece using a geographic information system.
An initial setting of the IH contribution within the overall aims of the project is provided. The specific hydrological topics covered are the climatological background to the Mediterranean mountainous zone; a statistical analysis of daily rainfall for the Basilicata area of southern Italy; an attempt to derive a trigger model for landslide movements at three sites in Basilicata; and numerical modelling of slope hydrology for a representative Italian site to assess rainfall effects on pore water pressure distributions.
The climate survey is presented for the three Mediterranean countries participating in the project - Italy, Spain and Greece - as a background to the understanding of rainfall in the field areas of particular concern; namely, Basilicata, the Eastern Pyrenees, and the Pindos Mountains.
The analyses of daily rainfall data for Basilicata provide depth-duration-frequency relationships over a wide range of durations and maps of mean annual maximum rainfall for different durations. A trigger model has been explored in an attempt to relate antecedent precipitation to occurrence of slope failure for the three sites of Grassano, Ferrandina and Pisticci.
The detailed modelling of slope hydrology is based on the solution of physical flow equations and investigates effects of rainfall parameters, slope material properties and land use characteristics on pore water pressure distributions since these play an important role in stability analyses. Pore pressures are modelled under current conditions and environmental change scenarios.
The final chapter combines the experience of these studies in suggesting a procedure for assessing rainfall-induced landslide risk on a spatial basis which is suitable for implementation within a geographic information system.