University of Twente Student Theses


Comparison of rainfall runoff models for the Florentine catchment

Rinsema, Jan Gert (2014) Comparison of rainfall runoff models for the Florentine catchment.

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Abstract:Entura is the engineering company of Hydro Tasmania which produces electricity in Tasmania, Australia. Most of the electricity is produced by hydro power plants. The lakes of the hydro power plant is filled with the rainfall from the area. To be able to us the power plant optimal, it is needed to predict the inflow in the lake. The prediction of the rainfall is done by rainfall runoff models employed by Entura. Historically four models are used: AWBM, GR4J, SYMHID and the VIC model. The choice of the model is based on experience and is not uniform for all the catchments and can lead to the wrong selection of a model for a catchment. This research tries to avoid the selection of not the best model by creating a stepwise model for the selection of a rainfall runoff model for a single catchment. This is done by selecting a rainfall runoff model for the Florentine catchment in Tasmania, Australia. To be able to evaluate the rainfall runoff models after calibration, six evaluation methods have been evaluated. The Nash Sutcliffe coefficient, the Index of Agreement and the Coefficient of determination evaluate the shape of the simulated runoff, compared with the observed runoff. The NS coefficient evaluates the shape best compared with the observed runoff. The Nash Sutcliffe coefficient is the most important factor of the proposed evaluation method. The Nash Sutcliffe method evaluates the shape best for both low flow and peak flow. The RVE evaluates the difference between the simulated and observed volume best and is the second important element of the evaluation method which should be included because the volume of water is important for watermanagement challenges handled by Entura. The calibration is done with treating the initial values with different methods. The initial value is treated as half full as parameter and is decreased with a startup time. The best results were achieved by treating the initial values as a parameter. Still it is advised to use a startup time because there is still the possibility of over- or under parameterization of the initial conditions. With a startup time this is reduced to minimum. When there is not enough data to include a startup time, the initial conditions can be treated as parameter in the Monte Carlo analysis. To decrease the influence of the input error, the rainfall gages were calibrated by Monte Carlo analysis. The results are mixed and do not give convincing improvements in calibration and validation for the Florentine Catchment. According to the comparison and evaluation of the AWBM, SYMHID and GR4J model the GR4J is the less sensitive model with the best output. The procedure which lead to the selection of the best result for the rainfall runoff model is recommended to Entura to Use in the future. The stepwise model proposed is: 1. Check if the lumped model is sufficient for the catchment. 2. Create a Monte Carlo analysis for GR4J, AWBM and SYMHID with 10000 runs a. Use a startup time if possible b. Otherwise treat the initial conditions as parameter 3. Evaluate the parameter sets with the formula of Ev. 4. Validate the models with a Split sample test. 5. Compare the results of the models and select the best model
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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