Alpine rivers are working for us

Study site

The Adige is the second longest river in Italy, rising in the Alps in the Autonomous Province of Bolzano near the Italian border with Austria and Switzerland, flowing 410 kilometers through most of North-East Italy to the Adriatic Sea.

In the territory called “Adige valley” the current river course is the result of heavy anthropic interventions of rectification done in the mid 1800's. This heavy hydromorphological alteration has been implemented to avoid floods, in particular to protect the highly intensive agricultural areas and urban settlements. On the other hand, rectification decreased the morphological and environmental quality of Adige river: artificial embankments and river straightening induced hydraulic and morphological alterations, such as increase of stream velocity and increase of bed erosion processes, and inhibited natural hydromorphological processes.

In 2011 the Province of Trento realized a river restoration intervention on Adige River, directly downstream the Noce confluence (46° 8'24.15"N - 11° 4'33.44"E), in order to re-establish fluvial dynamic. processes The restoration project consisted in a river channel widening involving the floodplain area present in the left river side. This project led to the current configuration of the area of interest, characterized by two distinct parts, a riparian area in the north portion and a secondary channel in the south part. Since 2006 the restoration site is part of the biotope “Foci dell'Avisio” (Site of Community Importance IT3120053), being the northern area border placed on Noce confluence. Monitoring and evaluation of the project results are actually the main objective and they could suggest eventual necessary project revisions. During the restoration activities made in 2011, 70,000 m3 of sediment have been removed and the material has been used for restoration works after landfills.

Another open question is the management of material coming from potential new excavation works in the floodplain. Monitoring results could suggest to re-introduce part of the sediment in the river, that is probably affected by erosion induced by low sediment supply from upstream.

Location and aerial view of project site

Restoration project

Planimetry of the project river reach before and after restoration

The main goal of the restoration interventions carried out was the return to the river part of the territory “stolen” in the past. The location of the widening intervention has been chosen counterbalancing technical feasibility and availability of territory. The project consisted in the demolition of part of the historic embankments of the river and removing and re-modelling the terrain in the nearby floodplain in a river reach 500 meters long. During the restoration works 70,000 m3 of sediment have been removed from the site in order to create a secondary channel that hydraulically activates only with high hydrometric levels in Adige river. Almost 500 meters upstream respect to this work, near Noce confluence, another minor restoration intervention has been implemented with the creation of a 100 meters long and 30 meters wide artificial riparian area connected to Adige river.