DEMO 3
Ljubljana, Slovenia

The City of Ljubljana as the Slovenian Capital (280,000 population) is one of the most flood-prone areas in Slovenia, especially its SW part, flooded by the Gradaščica River – hence, flood protection works were (are) foreseen which include NbS. Until now, 7.5 km of the Gradaščica River and Mali Graben channel were revitalised (Phase I), enlarged, and locally NbS elements were applied (channel widening, islands, side channels, fish refugia, bank vegetation – trees and bushes). The average annual damages are estimated at 5 Mio EUR/y. In 2025/26 the Phase II of the flood protection works will be executed, using various NbS.

As a part of the demonstration site is already constructed (Phase I), the DEMO3 will focus on continuous monitoring to gain insight into its functioning and to develop science-based guidelines on how to implement such measures including NbS elements elsewhere (important for replicators seeking flood risk management solutions in urban environments). The monitoring will be in the direction of hydromorphological changes (versatile hydraulic conditions during low-flows, bank erosion, local channel incision/aggradation, bed changes), vegetation dynamics, flow dynamics at low and high flows using fixed and field instrumentation for flow discharge, flow depth (water stage), and sporadic suspended load measurements during high flows.