Characterization of drainage system of four watersheds in Java a validation of fractal drainage networks

Bifurcation and length ratios of streams in a watershed havebeen reported b man researchers to be approximately constant. Four watershed in Java be Kali Garang in Central Java Closeh, Cisangkuy and Cikeruh in wester Java were characterized according toStrahler's order using Digital Elevation Model [DEM]. The DEM was de­ veloped from topographic maps of I: 25,000 scale. Kali Garang has bi­ fuurcation ratio that varies from 2 to 5 and relative length ratio of 1,9 to 3,66. While the rivers of the watersheds in western Java have bifurca­ tion ratios that varied from 3 to 6,31 and relative length ration of 1,38 to 3,57 The computed fractal dimension of the drainage network are 1,54: 1,74 : 1,55 and 1,73, respectively for Kali Garang Closeh, Cikeruh, and Cisangku. From these data, values and time of peak discharge can be calculated. These results confirm the fractal nature of the drainage networks as preionsl reported in man parts of theworld. This method can be applied in unscaling and downscaling vari­ ous existing hydrological characteristics of watersheds with different scales, and to simulate discharge characteristics from ungauged wa­ tershed. This indicates that hydrological researches shold minimize unnecessary works and focused on the essential tasks. The result uill facilitate watershed characterization and formulation of strategy on watershed management.