THE APPLICATION OF CELLULAR AUTOMATA TO INVESTIGATE RUNOFF ON SURFACEOF COMPLEX TOPOGRAPHY UNDER DIFFERENT RAINFALL SCENARIO

Abstract

Overland flow development on a steep slope area is the major source of non-point pollution from rainfall event to receiving surface water bodies. The mechanism of runoff is a complex and non-linear system that can be influenced by infiltration excess, saturation excess, and subsurface flow. Because of these limitations of hydrological measurement techniques, the true complexity and heterogeneity of the hydrological process in the fields, the quantities of overland flow under rainfall are not fully to define despite their importance. In this research, we present an application of Cellular Automata (CA) in a computation model to simulate surface runoff on the complicated shape of the hillslope. The first contribution of research was applying the wall boundary and flooded condition into CA method to ensure the accuracy of the method physically. Besides, modified CA-rules were also developed to correct and speed up the implementation. In addition, these factors that effect to the behavior of runoff such as rainfall regime, an interception from covered vegetation (plant, tree, grass, bush), infiltration based on soil characteristic, and roughness of surface were also considered in the CA rules of computation model. The output of the mathematical model succeeded could be promising to treat rainfall-runoff on the real field. The accuracy of CA runoff method is also investigated and proved through convergence study.