FLOOD 1. Final Report

The FLOOD 1 project was carried out by the French Geological Survey (BRGM), the University of Brighton and the British Geological Survey from April 2004 to June 2008 inclusive. It was carried out under the INTERREG IIIA initiative of the European Union which provided 50% of the funding, the remainder coming from the three project partners and a number of industrial partners who also formed the Project Advisory Group. The project was set up to develop appropriate early warning systems for groundwater flooding in Chalk catchments following the particularly severe groundwater floods during the winter of 2000-01. It focussed on flooding in the Patcham area of Brighton and in the Somme Valley of northern France. Research sites were set up to the north of Brighton and in the Hallue sub-catchment of the Somme. An additional site was established at East Ilsley in the Pang Valley of the Berkshire Downs; a Chalk catchment that suffers from groundwater flooding, has been extensively studied and within which there are a number of research sites which were established for the LOCAR thematic research programme. Three main objectives were addressed by the project, namely: (i) To understand the hydraulic behaviour of water flow in the unsaturated zone which leads to triggering of groundwater flood events. (ii) To develop unsaturated zone monitoring techniques, including non-intrusive ones such as Magnetic Resonance Sounding (MRS), to reduce cost and environmental impact, and to improve areal representation of the data. (iii) To produce more appropriate methodologies and tools for forecasting groundwater flood events capable of operating within a much longer timescale than is currently possible (i.e. days and weeks rather than hours). Whilst FLOOD 1 was a joint project, this report only covers the work carried out by the BGS. Separate reporting procedures will be followed by the other two partners and a joint report prepared for the INTERREG authorities by the overall project leader (BRGM) will contain each partner’s technical report as annexes. During the life of the project a number of joint meetings were held to discuss progress and various issues in the development of our understanding of the processes involved in groundwater flooding in the Chalk. The only project staff working full time on the project were two Research Assistants based at the University of Brighton. The detail of their work will appear as their PhD theses in due course. The project succeeded in addressing all three of the objectives outlined above and has without doubt increased our knowledge of the unsaturated zone of the Chalk, not least because it provided unique observations of water movement in this zone.