Self-organized critical drainage networks

We introduce time-dependent boundary conditions in a model of drainage netw ork evolution based on local erosion rules. The changing boundary condition s prevent the model from becoming stationary; it approaches a state where f luctuations of all sizes occur. The fluctuations in the sizes of the draina ge areas show power law behavior with an exponent that differs significantl y from that of the static distribution of the drainage areas. Thus, the mod el exhibits self-organized criticality and proposes a novel concept for pre dicting fractal properties of drainage networks.