Authors : Sasmito , B. Triatmodjo, J. Sujono and Br. Sri Harto
Abstract: Unit Hydrograph (UH) is a popular method for predicting flood caused by rainfall in a catchment. This method has little flexibility to different storm, consequently the unit hydrographs produced differ considerably from storm to storm. This is partially due to the unit hydrograph method ignores the influence of Antecedent Soil Moisture Condition (AMC) on runoff generating processes. This paper presents the research result on the characteristics of unit hydrograph with different scale of AMC. In this research the AMC was approached by parameter of Antecedent soil Moisture Deficit (AMD) which has opposite meaning with the AMC. The AMD was represented by the dependent variable of Sc (Storage capacity) that is the space volume remaining the soil moisture evaporated. The research was conducted using hydrologic data (rainfall, discharge and evaporation) assembled from four catchments. The characteristics of unit hydrograph were presented by peak discharge (qp) and time to peak (tp) of unit hydrograph. The research experiment were performed using three parallel tanks and one serial tank model of Yue and Hashino. The research result are concluded; the unit hydrographs derived with base-flow separation using tank model (HSsim) show more consistent than the unit hydrographs calculated by conventional method HScol; AMC influences the effective rainfall as the AMC becomes bigger than so do the effective rainfall as the AMC trends to smaller than the peak discharge (qp) becomes smaller; the influence of AMC to time to peak (tp) cannot detected by this model.
Sasmito , B. Triatmodjo, J. Sujono and Br. Sri Harto, 2016. The Characteristics of Unit Hydrographs with Different Scale of Antecedent Soil Moisture Condition. Journal of Engineering and Applied Sciences, 11: 2594-2601.