The development of river basins subject to inundation requires a proper method of estimating possible damage resulting from a flood with a given return period.In the present study, a distribution function is developed, with the capability of providing an acceptable estimation of possible damage which may be incurred during a known flood.Based on the theory of extreme values in stochastic processes, a distribution function for the damage suffered is derived, assuming that the values of the extremes of exceedances are independant and identically distributed in the time interval (0, t] for a given year and season.