Analysis of Runoff Aggregation Structures with Different Flow Direction Methods under the Framework of Power Law Distribution

Abstract

The main purpose of this study is to evaluate the performances of different flow direction methods (FDM) in affecting the runoff aggregation structures within a watershed under the framework of power law distribution. To this end, SFD (single flow direction method), MFD (multiple flow direction method) and IFD (Infinite flow direction method) were applied for determination of flow direction for water particles in Susu river basin, and consequently assessed with respect to the variation of flow accumulation. The results indicate that different patterns of flow accumulation were observed from each flow direction method. Effect of flow dispersion on DEM is strongest with ascending order of SFD, IFD, MFD. However, contribution of individual pixels into outlet follows descending order of SFD, IFD, MFD. Notably MFD and IFD tend to make additional hydrologic abstraction from rainfall excess due to the flow dispersion within the flow paths generated on DEM. This study also investigated the size distribution of flow accumulation which is equivalent to the drainage area generated from the selected FDM. They were fitted to the power law distribution and flow accumulation was recognized as a scale invariance factor based on the parameter estimation for power law distribution by maximum likelihood. It was also noticed that FDM affects the parameter estimation of power distribution where highest exponent was estimated for MFD following by IFD and SFD. © 2018, Springer Nature B.V.