A Comparison of Design Storms for Urban Drainage System Applications

Abstract

The present research develops a systematic application of a selected family of 11 well-known design storms, all of them obtained from the same rainfall data sample. Some of them are fully consistent with the intensity–duration–frequency (IDF) curves, while others are built according to typical observed patterns in the historical rainfall series. The employed data series consists on a high-resolution rainfall time series in Valencia (Spain), covering the period from 1990 to 2012. The goal of the research is the systematic comparison of these design storms, paying special attention to some relevant quantitative properties, as the maximum rainfall intensity, the total cumulative rainfall depth or the temporal pattern characterising the synthetic storm. For comparison purposes, storm duration was set to 1 hour and return period equal to 25 years in all cases. The comparison is enhanced by using each of the design storms as rainfall input to a calibrated urban hydrology rainfall–runoff model, yielding to a family of hydrographs for a given neighbourhood of the city of Valencia (Spain). The discussion and conclusions derived from the present research refer to both, the comparison between design storms and the comparison of resulting hydrographs after the application of the mentioned rainfall–runoff model. Seven of the tested design storms yielded to similar overall performance, showing negligible differences in practice. Among them, only Average Variability Method (AVM) and Two Parameter Gamma function (G2P) incorporate in their definition a temporal pattern inferred from empirical patterns identified in the historical rainfall data used herein. The remaining four design storms lead to more significant discrepancies attending both to the rainfall itself and to the resulting hydrograph. Such differences are ~8% concerning estimated discharges.

Evaluation of Design Storms and Critical Rainfall Durations for Flood Prediction in Partially Urbanized Catchments

“…Although some authors have criticized frequency based methods, primarily because they do not represent actual historical rainfall [15,28], other authors have found that these methods agree well with historical storms. For example, Balbastre-Soldevila et al [22] found that the ABM method produced average peak flow rates in an urban catchment in Spain similar to several other geometrical methods and the AVM design storm, and Na and Yoo [29] reported that the ABM method was most similar to historical storms in Korea.…”

“…Some popular methods belonging to this group include the triangular [18], double triangle [19], Sifalda [20] and linear-exponential method [21]. A recent overview and comparison of various geometric pattern methods is available in [22]. However, in this study, we focus primarily on the other two methods.…”

“…They focused mostly on frequency based methods and Huff's curves and concluded that the choice of the rainfall duration and design storm had a significant impact on the overall flooding results. Finally, Balbastre-Soldevila et al [22] compared 11 well-known design storms for an urban drainage system application in Spain and recommended the AVM and a two-parameter Gamma function [38] as the most appropriate.…”

“…Despite significant efforts in evaluating and deriving design storms, the engineering community is still far from a unified view on the optimal choice of a design storm for flood estimation. The lack of clear guidelines and recommendations can be explained by the fact that previous studies [13,16,22,28,29,[34][35][36][37] had sometimes contradictory findings, which suggests that the choice of the optimal design storm depends on the catchment characteristics (size, slope, and land use [41]) and local climate (rainfall). Some of the studies that examined design storms were focused only on the hyetograph shape without an appropriate hydrological or hydraulic analysis [34,36]; some were focused only on stormwater drainage systems and urbanized catchments [22,28,37]; and some were based on a cross-comparison of different design storms without a suitable reference point (e.g., historical event) [16,22,37].…”

Flood Risk Assessment in an Underground Railway System under the Impact of Climate Change—A Case Study of the Barcelona Metro

“…Climatic variables' projections unto 2100 are forecasting within project RESCCUE. This study embraces these rainfall projections to create design storms (using alternating blocks method, according to recommendations produced near the study area [64]). After running the hydrodynamic model for the future expected conditions, including climate change influence, hence obtaining the pluvial floods to assess expected future impacts.…”