engleski

The Influence of Heavy Rainfall on the Landslide Initiation

Combined use of engineering geological and hydrogeological data with meteorological information is of great interest in investigation of landsliding. Landslide can be caused by several factors, including geological, morphological, physical and human, but only one trigger usually initiates landsliding. By definition, a trigger is an external stimulus, such as an intense rainfall, that causes a near-immediate response in the form of a slope failure. The requisite short time frame of cause and effect is the critical element in the identification of a landslide trigger. In this paper a compilation was made of geological, morphological, hydrogeological and meteorological data, in order to illustrate their combined influence to landsliding. As an interesting example from Croatia, a recent slope failure, activated in the period of a heavy rainfall during winter 2000/2001 was chosen. Preparatory causal factors of this slope failure were illustrated on engineering geological model where the following ground conditions were shown: slope geometry, different lithological units derived on the basis of their physical-mechanical properties and hydrogeological conditions. Adverse human activity in the form of excavation in the landslide area were treated only as additional preparatory causal factor, because the slope was in stable condition until the period of heavy rainfall. In the focus of this paper was the comparison of meteorological data (daily precipitation) and slope failure initiation in a short time frame. On the basis of the rainfall intensity for the period of interest and relevant IDF curves, the return period of critical rainfall was determined as considerably lower than 2-years return period. The selected example illustrated the necessity of comprehensive use of field information, which encompasses geological, hydrogeological, geomorphological and meteorological data in the investigation of landslide causes.

landslide trigger; storm; ITP curve; landslide frequency analysis; Croatia

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