Self-affinity in braided rivers

Three braided rivers of different scales and different hydrologic/geomorphologic characteristics (the Aichilik and Hulahula in Alaska and the Brahmaputra in Bangladesh) are analyzed for spatial scaling using a logarithmic correlation integral method developed earlier by the authors. It is shown that the rivers exhibit anisotropic scaling (self-affinity) with fractal exponents nu(x) = 0.72-0.74 and nu(y) = 0.51-0.52, the x axis being oriented along the river and the y axis in the perpendicular direction. The fact that despite large differences in scales (0.5-15 km in braid plain width), slopes (7 x 10(-3) to 8 x 10(-5)), and types of bed material (gravel to sand), the analyzed braided rivers show similar spatial scaling deserves special attention. It might indicate the presence of universal features in the underlying mechanisms responsible for the formation of the spatial structure of braided rivers. Also, comparison of fractal characteristics of braided rivers with those of single-channel rivers and river networks suggests that braided rivers form a class of fractal objects lying between the classes of single-channel rivers and river networks.