A COMPARISON BETWEEN RANDOM AND DETERMINISTIC DYNAMICS OF RIVER DRAINAGE BASINS FORMATION

Resumo

This work contributes to the discussion on how and why tree networks in drainage basin arises in nature. A fully deterministic erosion model recently developed was used to explain the spontaneous origin of river networks, which until then was assumed to be due to the optimal reduction of the flow resistance in a area to point flow. A random evolution model was devised in order to investigate the contribution of two separate features: the relative area size of the network and the structure (configuration) of the network. Two random models were applied, namely, restricted random choosing selection and fully random. Results showed that indeed the mere presence of low flow resistance portions of the basin does improve global performance and that randomness does not create networks. Further gain in performance is given by the network formation by erosion or by optimization. This suggest that local factors also are important to the explanation of the very existence of natural networks.