ABSTRACT
Cellular automata are discrete and dynamical systems that are divided up into small cells with each cell taking a certain state. The basic idea of cellular automata is to reduce a complex system of complex rules into something simpler. In the study of cellular automata, some scholars have done the following works: Simulations of the Armaconi Basin, Calabria, Italy showed encouraging results which were in agreement with the findings of other studies (Ambrosio & Gregorio 2001). The cellular model of river avulsion highlights the need to develop models of floodplain evolution at large time and space scales to complement the improving models of river channel evolution (Jerolmack & Paola 2007). The cellular model of braided rivers suggests that the only factors essential for braiding are bedload sediment transport and laterally unconstrained free-surface flow (Murray & Paola 1994). The simulation of braided river flow using a new cellular routing scheme represents a small and ongoing contribution to the field of numerical simulation of braided river processes (Thomas & Nicholas 2002). The modeling of hillslope runoff and soil erosion at rainfall events suggested that the CA model was an applicable alternate for simulating the hillslope water flow and soil erosion (Ting & Hu 2009).
In this study a novel numerical cellular automata model for riverbed evolvement process was developed. The model was applied to one part catchment of the Wei River the largest tributary of the Yellow River which part is a typical type wandering stream. The dynamics of wandering stream are complex; channels migrate laterally, split, rejoin and develop bars, with the flow shifting unpredictably from one part of the network to another. This model we describe here is a simple, deterministic numerical model of water flow over a cohesionless bed that captures the main spatial and temporal features of real wandering rivers. It involves a number of states including altitude, water depth, total head, infiltration, erosion, sediment transport and deposition. The impact of factors like size of the spatial cell, hydraulic parameters, and the setting of time step and iteration times on the model accuracy was discussed. The comparison of the simulated and measured data suggested that the cellular automata model was an applicable alternate for simulating riverbed evolvement process.
