Fractal Characteristic Analysis of Watershed as Variable of Synthetic Unit Hydrograph Model

Abstract

Fractal characteristic of watershed is an important parameter which influences the formation of synthetic unit hydrograph. Based on a previous study, hydrology response of watershed expressed in hydrograph form could be well presented by hydrology network characteristic as a form of fractal characteristic of watershed [1]. Fractal characteristic of watershed was stated as fractal dimension which was presented in three parameters i.e. river branch ratio (RB), river length ratio (RL) and watershed river area ratio (RA). The purpose of this research was to analyze fractal characteristic and to verify its fractal dimension stability as preliminary research to prepare variables which would be used to develop synthetic unit hydrograph model in the future. Analysis was undertaken using two methods i.e. Horton’s Coefficient Ratio and Box Counting Dimension. Analysis result revealed that fractal dimension of river network from 8 watersheds calculated using those two methods could give almost the same result, ranged from 1 to 2. Fractal dimension from calculation also showed similarity with study conducted by Tarboton et al. [2], Balkhanov et al. [3], Khanbabaei et al. [4], obtaining that fractal dimension of river network is generally in the range of 1 to 2.