Capability of Cellular Automaton in Simulation of Evolution and Erosion in river Systems (Case Study: Lighvan Catchment)

Catchments and river systems altered in response to changes of internal and external factors. Hence, several techniques have been proposed to simulate these changes and Evolution of the river systems. Cellular Automaton is one of the newest river cellular models that define the catchment landscape with a grid of cells, and development of this landscape is determined by the interactions between cells (for example fluxes of water and sediment) using rules based on simplifications of the governing physics.This method is used for simulation of Lighvan catchment with 20 m cell size and 10 years precipitation data (1380 to 89). Simulation results evaluated in two qualitative and quantitative methods, So that the relative changes in the catchment and spatial distribution of erosion and aggradation value in the entire catchment and each cell was identified on Digital Elevation Model map and also, values of different particle size distribution ​​in different discharges showed that with the increasing discharge, and amounts of sediment increased and among this coarse sand have the highest value and very fine sand, clay and silt particles have the lowest value. Also investigation of longitudinal and latitude profile show that Lighvan river is in mature stage and Lighvan channel has been underwent aggradation due to climate changes and increasing catchment precipitation in last decade that causes hillslope erosion and channel aggradation. Finally, Since certainty of Cellular Automata results is difficult and CAESAR is sensitive to input parameters but comparing the results with previous investigation and field observation shows that Cellular Automata has acceptable results.