Study of spatial scaling in braided river patterns using synthetic aperture radar imagery

Abstract

Synthetic aperture radar (SAR) imagery offers an appealing way of remotely monitoring the complex and rapidly changing forms of braided rivers. These rivers are often found in scarcely inhabited regions and are so dynamic that in situ measurements are almost impossible. In this paper, SAR imagery was used to extract braided river patterns such that their spatial scaling characteristics could be studied. From analysis of several reaches of a braided river in Alaska (the Tanana River), self-affine spatial scaling of the river patterns was found to be present under different flow rates and in different seasons when the river was undisturbed (free of external topographic controls). In regions where predominant geologic controls (i.e., mountains) or predominant flow paths (several tens of times the size of the other channels) were present, no spatial scaling was found. When scaling was found, the values of the anisotropic scaling exponents ν(x) and ν(y) had very similar values to those found by Sapozhnikov and Foufoula-Georgiou [1996] from traced and digitized aerial photographs of several braided rivers.