Calibration event selection for green urban drainage modelling

Abstract

Abstract. Calibration of urban drainage models is typically performed based on a limited number of observed rainfall-runoff events, which may be selected from a longer time-series of measurements in different ways. In this study, 14 single- and two-stage strategies for selecting these events were tested for calibration of a SWMM model of a predominantly green urban area. The event selection was considered in relation to other sources of uncertainty such as measurement uncertainties, objective functions, and catchment discretization. Even though all 14 strategies resulted in successful model calibration, the difference between the best and worst strategies reached 0.2 in Nash–Sutcliffe Efficiency (NSE) and the calibrated parameter values notably varied. Most, but not all, calibration strategies were robust to changes in objective function, perturbations in calibration data and the use of a low spatial resolution model in the calibration phase. The various calibration strategies satisfactorily predicted 7 to 13 out of 19 validation events. The two-stage strategies performed better than the single-stage strategies when measuring performance using the Root Mean Square Error, flow volume error or peak flow error (but not using NSE); when flow data in the calibration period had been perturbed by ±40 %; and when using a lower model resolution. The two calibration strategies that performed best in the validation period were two-stage strategies. The findings in this paper show that different strategies for selecting calibration events may lead in some cases to different results for the validation period, and that calibrating impermeable and green area parameters in two separate steps may improve model performance in the validation period, while also reducing the computational demand in the calibration phase.

Modelagem hidrológica e hidráulica usando o SWMM - Storm Water Management Model na bacia urbana do Riacho Fundo I - Distrito Federal

“…Ferramentas, como a modelagem hidrológica e hidráulica, trouxeram avanço na gestão dos sistemas de drenagem urbana. O modelo SWMM -Storm Water Management Model pode ser aplicado desde as fases de planejamento e análise dos sistemas existentes, como também no dimensionamento de novas estruturas, inclusive com a aplicação de medidas de Desenvolvimento de Baixo Impacto (Low Impact Development-LIDs) (Zhang et al, 2020;Broekhuizen et al, 2019;Xu et al, 2018;Barros et al, 2016). Além disso, o SWMM permite a simulação do fluxo nos condutos por meio da onda dinâmica, que considera os efeitos de remanso, fluxo reverso, fluxo a superfície livre e sob pressão, comum em sistemas de drenagem sobrecarregados, e gera resultados mais precisos.…”