 The worst floods were in 1971, when 51 of the 54 districts of the state were affected — an area of nearly 52,000 square kilometres.The eastern districts are the most vulnerable to floods, the western districts slightly less and the central region markedly less.The eastern districts susceptibility to floods is ascribed, among other things, to heavy rainfall, low flat country, high subsoil water level and the silting of beds which causes river levels to rise.