Detailed design of flood control and environmental restoration measures, in the Serpis River Basin (Spain)

ACUAMED - Water Authority of Mediterranean Basins

The proposed actions in Gandia are as following:

• Defence against floods:
  • Stretch III y IV: Concrete wall coated of left bank, shallow water channel
  • Stretch V: Combination of wall concrete and flood protection dam in the left bank. Concrete wall in the right bank for protection of the slope and walls in the shopping areas.
  • Stretch VII: Regrowth of existing dams in both banks to its mouth.
• Environmental adaptation
  • General cleaning of the area.
  • Treatments on the existing vegetation in the area that is affected by the works
  • Channels of shallow waters in stretch III, IV and V in order to create a sheet of standing water next to the town of Gandia.
  • Treatments of new vegetation through planting, hydro seeding and plantations to facilitate the environmental integration of walls, dams, channel of shallow water, roads and restore areas affected by the works.
  • Pedestrian walkway along the different stretch of performance, taking advantage of the terraces of the river and the work of defence against floods.
  • Environmental adaptation of the Park of the Ambrosías on the left bank of the stretch I and II.

Terrateig:

Terrateig Weir. The project calls for the construction of a concrete weir, which will remain empty under normal operating conditions, and whose purpose is to abate flooding from the Rambla Vernissa intermittent stream. It is 422.80 m long and 3.00 m wide. It has surface spillways for a total length of 60 m. The maximum height of the weir over its foundation is 26.50 m, and 22.50 m over the bed.
Protection against erosion in Llocnou de Sant Jeroni. The right bank of the River Vernissa, in the stretch passing through the town of Llocnou de Sant Jeroni, is affected by erosion problems. The construction of a rubblework wall, built in two sections, is planned to resolve this problem.
Protection against flooding in Rótova. This consists of the construction of a reinforced concrete wall that replaces an existing concrete block wall in the area of the Rótova sports centre, on the left bank. The wall will prevent the flooding problems that currently arise in this area.
New Rótova bridge. The bridge is intended to connect the banks of the river, even in the event of flooding, and will be an extension to Les Planes Street on the right bank in Rótova.
Protection against erosion in Rótova. The construction of a rubblework wall is planned, which will be an extension of an existing cemented rock fill wall on the left bank.
Demolition of a walkway in Beniarjó. This walkway is a serious obstacle to water flow. The detail design calls for its demolition in order to improve the hydraulic capacity of the watercourse.
Protection against erosion in Beniarjó. In this area, the watercourse becomes more sinuous; therefore, riprap protection has already been installed. The planned work pursues the same objective, to ensure that the terraces on the right bank and the dwellings on the left bank are protected against possible erosion. Because of the characteristics of the bed, it was found that riprap could be put in place, which would also afford the best environmental integration. This type of protection is also consistent with the existing riprap on the right bank.
Piles – Serpis diversion. To prevent flooding in the Piles ravine downstream of the AP-7 motorway, part of the flow from the ravine is diverted to the River Serpis. This diversion takes place by means of a canal with a rectangular cross-section (10.50 m wide and 5 m deep). The headworks include a diversion weir. Delivery is through a stepped chute that returns the water to the River Serpis.