Intervention to Reduce Hydraulic’s risk along the Nera River-Terni-Narni Section

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Client Consorzio di Bonifica del Tevere Nera

Location Umbria

Status in corso

Intervention to reduce the hydraulic risk along the Nera River in the Terni/Narni section

Topographic surveys, hydraulic study-Technical-economic feasibility  and final design aimed at reducing hydraulic risk and the protection of areas at hydraulic risk R3 (high) and R4 (very high).

The project involves the reduction of the hydraulic risk along the Nera river in the Terni-Narni section, between the bridge connecting Maratta and the E45 highway and the Augusto bridge (Narni). On the design flood flow, the value of 620 mc/s (QTr = 200 years) was assumed to be constant along the entire stretch under consideration. In particular, the planned interventions concerned the hydraulic safety of the areas classified as R3 or R4 at risk by the Tiber River Basin Authority. Specifically, they are: the industrial area of Narni (Carbon Spa and Tarkett Group), the SS.3 road and surrounding areas for a development of about 2.5 km and the areas with production activities adjacent to the SP 24 (Maratta Bassa).

The aim of the project: reducing hydraulic risk in the areas potentially flooded by the Nera river and characterized by the presence of private, commercial, industrial buildings and infrastructures. The hydraulic study concerned the simulations of the flood runoff concerning the stretch of the Nera River between the center of Terni and the industrial area of Narni on the basis of hydrological studies and was drawn up on the basis of a digital terrain model (DTM) reconstructed using the available topographic surveys and appropriately integrated with  appropriate topographic campaign. The assessment of flood areas was carried out using the HEC RAS 6.1 calculation code, developed by the US Army Corps of Engineers by applying an integrated 1D – 2D model, i.e. consisting of a one-dimensional (1D) model in the riverbed and a two-dimensional (2D) model in flood areas.

Intervention Planning:

  1. New earth embankments and reinforced embankments
  2. Upgrading of existing embankments
  3. embankment in reinforced earth, replacing the existing earth embankments
  4. reinforced concrete retaining wall, with foundation piles;
  5. Armed Lands
  6. reinforced concrete retaining wall (without foundation piles)
  7. Asphalt road elevation
  8. Elevation of a dirt road