Calibration of urban stormwater drainage models using hydrograph modelling

Abstract

Use of mathematical models requires the estimation of model parameters, which is usually known as the calibration of the model. In general, parameter optimization is preferred in model calibration to the trial-and-error visual comparison of observed and modelled output responses, due to subjectivity and the time-consuming nature of the latter approach. An optimization procedure, called two-stage inner/outer optimization, is described in this paper, which can be used to estimate the model parameters of any urban stormwater drainage catchment modelled with any urban drainage computer modelling software. However, the ILSAX computer software was used in this study. The method is designed to provide the 'best' set of model parameters that consider several storm events simultaneously. Impervious area parameters are obtained from frequent 'small' storm events, while the pervious area parameters are obtained from less-frequent 'large' events. The Giralang catchment in Canberra (Australia) was used to demonstrate the method. Several 'small' and 'large' storm events of the catchment were considered in parameter optimization. Few other storm events, which were not used in model calibration, were used to validate the model parameters obtained from calibration. Results from both calibration and validation showed that the 'best' set of model parameters obtained for the catchment was able to produce hydrographs similar to the observed hydrographs. Pervious and impervious area parameters obtained from calibration agreed well with the information gathered from other sources such as aerial photographs and published literature.

Investigation and Simulation of Flood Inundation Hazard in Urban Areas in Iran

“…Rainfall runoff modeling using SWMM model SWMM is used to simulate the storm sewer ow component. To use the simulation models, it is necessary to estimate the model parameters relevant to the urban drainage system (Dayaratne and Perera 2004).…”

“…The use of mathematical models requires the estimation of model parameters, which is usually known as the calibration of the model (Dayaratne and Perera 2004). No matter how good and precise the model is, it can never describe the complete complexity of nature.…”

Regionalisation of impervious area parameters of urban drainage models

“…As can be seen from Table 2, the results obtained from different methods do not show any significant inconsistencies. The estimation of model parameters through inner/outer optimisation and RR plots is described in detail including examples in Dayaratne (2000) and Dayaratne and Perera (2004).…”

“…The method was designed to provide the 'best' set of model parameters that considers several storm events simultaneously considering all attributes of hydrographs such as peak discharge, runoff volume, time to peak and shape. The details of the method are given in Dayaratne (2000) and Dayaratne and Perera (2004). During inner optimisation, the model parameters DCIA and DS i were obtained through optimisation by linking the ILSAX model (with data related to each storm event) with the parameter optimisation software, PEST (Watermark Numerical Computing 1998).…”

“…The task (b) above by itself contains material for a separate paper and had been the subject of a paper by the authors (Dayaratne and Perera 2004). However, a description of the calibration procedure and the results of calibration of the ILSAX models of the study catchments are given in this paper.…”