Control of channel bank erosion using permeable groins

An experimental erosion control scheme in the Niger Delta was designed as a permeable groin using timber piles laced with strong cane nets. At the onset of the rains, when external channel water level was only 10 percent of its seasonal peak, a failure of the peripherial groin was recorded, which apparently was due to local sliding in the bank. At peak flood, a timber pile probably buried to a shallow depth failed, making the system of groins ineffective. The failure of the single timber pile resulted in extensive scouring and bed degradation, leading ultimately to the failure of the protective structure. Analyses carried out confirm that depth of embedment of the pile system is the single most important factor ensuring the stability of the groin structure.