OPTIMAL CHANNEL NETWORKS - A FRAMEWORK FOR THE STUDY OF RIVER BASIN MORPHOLOGY

Optimal channel networks (OCNs) are dendritic structures obtained by m inimizing the local and global rates of energy dissipation in a contin uously fed (in space and time) plane aggregation system reminiscent, a nd based on the properties, of the planform of three-dimensional natur al drainage networks. Geomorphological and fractal properties of OCNs are known from earlier studies by the authors. This paper explores fur ther the structures derived by optimization of energy dissipation rate s. Optimality of subnetworks and of basin shapes is investigated as a by-product of competition for drainage. A new perspective on the possi ble prediction of the width function of a basin network, and hence of its hydrologic response, is obtained by exploiting OCN techniques, req uiring only the definition of the outer boundaries of the basin. The i nterplay between hillslope processes and the development of drainage n etworks is addressed, aiming at the relative role and the mutual inter relations of geology and optimal organization in the structure of matu re river basins. Also addressed is the issue of multiscaling and multi fractality in the spatial organization of the network. It is concluded that OCN approaches provide a comprehensive framework for the study o f the morphology of geophysical structures.