After the floods in 1995, 1999 and 2000 many houses and public facilities on the Saâne River watershed in northern France were damaged. During the following years the Saâne River water authority implemented approximately 40 water retention installations in order to protect the territory from flood hazard.

The related studies enabled to update the existing knowledge of the Saâne valley watershed, particularly regarding the water management facilities. The studies also enabled to assess the economic impact of the floods and develop a water management network masterplan.


o State of play (surveys, on-site investigations, documentation collection…)
o Hydrological analysis and classification of flood types
o Design floods
o Hydrological and hydraulic modelling
o Flood risk areas and flood duration mapmaking
o Hydrological and hydraulic impact assessment of each simulation
o Drafting and feasibility of the different hydraulic development layouts
o Cost estimate of the damages for each simulation
o Detailed calculation of the cost of works
o Drafting of a long-term action plan for the project completion
o Results reporting meetings with the local authorities


Saâne River water authority

Key figures

Period of services

September 2010 - February 2013

Key challenges

Among 5 evaluated scenarios, the selected development program comprises:
o Development of 6 dynamic flood retention zones (dams),
o Securing of 6 existing retention structures,
o Natural flood management measures: recovery and expansion of flood plains by removing embankment in the valley,
o lowering of 5 former thresholds.
This masterplan was subject to a financial estimate and detailed planning.