River Roe Feasibility Study, Co. Londonderry

Doran Consulting was commissioned by DRD Rivers Agency to undertake a feasibility study which considered the condition of the manmade floodbanks adjacent to the River Roe and its tributaries for 12.7km from Limavady Roe Bridge to Lough Foyle.  A topographical survey (including an aerial survey), a site investigation and a condition inspection with photographic record were conducted for over 30km of floodbank.  These surveys were used to analyse the slope stability and water levels within the River Roe, to estimate flooded areas and to determine the overall condition of the current floodbanks.

A computer based mathematical model of the river system was created which included several bridges and weirs.  The influence of sea level was considered and the lengths and position of floodbank that needed to be raised to prevent future flooding from different return periods were presented.  A range of design options was considered to repair or strengthen the existing floodbanks.  The provision of a flood warning procedure was also examined.  The different design options were then evaluated against environmental scoping and an economic appraisal.

The proposed design option concentrates on protecting the large area of land adjacent to the left floodbank.