Scenario-based inundation risk analysis of potential ship lock gate failure at Kaunas hydropower plant

A new ship lock through Kaunas hydropower plant is currently at the design stage. It will be the largest construction of this type in Lithuania. During exploitation, a navigation lock might be affected by numerous risk factors, such as structural deterioration, technical equipment failures, changes in environmental conditions, and human factors. In this paper the potential ship lock failure and resulting inundations when gates become misaligned due to asymmetrical pressure, jammed due to accumulated garbage or ice, or mechanical failure were investigated. The following scenario was adopted: ship lock experience failure during high probability (10%) spring flood, resulting in the total discharge of 2,729 m3·s-1. The inundations of the consequential increase of the water level in the Kaunas city were modelled using HEC-RAS software and the digital river channel relief model that combined bathymetric data with laser scanning (LiDAR) data. The results showed that most of the River Nemunas in Kaunas remains within its banks, but inundation becomes significant in some places. It is particularly noticeable near Nemunas Island, where the water could completely inundate the building of the Science Island. A total of 27 buildings would be affected in the analysed area.