The Impact of Deep-Seated Landslides on Reservoirs and Rivers in Vrancea Seismic Region

Abstract

The impact of deep-sated landslides on reservoirs and river network has a long history within Vrancea Seismic Region. During the last 100 years, tens of such landslide cases were noted, blocking valleys and forming temporary and permanent lakes. Also, the reservoirs built for complex purposes are affected by deep-seated landslides, causing major disturbances in their activity, especially due to an accelerated silting process. Several case-studies were considered, among which Siriu landslide (250,000 m², more than 2 mill.m³; blocked Siriu reservoir) and Zăbala landslide (1,900 m long; blocked Zăbala River). The study emphasize the role of earthquakes, long-lasting autumn rains and spring showers overlapping snowmelt in preparing and triggering such phenomena and also the role of reservoir level variations, as a result of inflow-outflow variability. The study represents an important step in understanding the behaviour of old, peri-glacial landslide reactivations and also a progress towards a better hazard assessment.