Study Of Flood Using GR4J Rainfall-Runoff Model At Citarum Hulu Watershed

• Main Author: MUHTAJ MUNAJAT (NIM : 95007004); Pembimbing : Dr.Ir. Dhemi Harlan, CECEP
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/15218
• Institution: Institut Teknologi Bandung

This thesis recites rainfall-runoff modelling using GR4J at Citarum Hulu. The input of the model are daily precipitation and potensial evapotranspiration which the result are calibrated with observed inflow. In this model we look for optimum value of four free parameter GR4J model which produces minimum error. There are two phase in the modeling, i.e. calibration model and validation model. Calibration model use five year data in the begining and validation data use the last five year of data. We use Nash-Sutcliffe Coefficient method and Relative Volume Error method (RVE) to counting error. This study is started by developed program GR4J model use software Matlab 7.0. The input for modeling are regional precipitation which counted by using Polygon Thiessen method and potential evapotranspiration which counted by using Pennman Modification method. The objective goal of this modeling is search optimum value of four free parameter GR4J i.e. Maximum Capacity Of Production Store (X1), Groundwater Coefficient (X2), Maximum Capacity Of Routing Store (X3), and Peak Time Of Ordinat Unit Hydrograph (X4). The last parameter, time peak of ordinat unit hydrograph is used for flood study analysis, in this thesis we use linear reservoir cascade to analyse the unit hydrograph. In this thesis the GR4J model is compared with NRECA rainfall-runoff model. This study is conducted using Citarum watershed which is a gauged watershed. The calibration is use observed Citarum discharge at Nanjung station and based on observed rainfall data at several rainfall stations within Citarum watershed. The result show that the first five year data is identical with the last five year data. This result means the pattern of precipitation and inflow not extremely change. The deviation it is less than 0.85 show that rainfall-runoff modeling is not only influenced by four free parameter of GR4J but also influenced by other external factor.