Articles | Volume 22, issue 1
Hydrol. Earth Syst. Sci., 22, 417–436, 2018
Hydrol. Earth Syst. Sci., 22, 417–436, 2018

Research article 18 Jan 2018

Research article | 18 Jan 2018

The role of storm scale, position and movement in controlling urban flood response

Marie-Claire ten Veldhuis1,2, Zhengzheng Zhou2,3,4, Long Yang2, Shuguang Liu4, and James Smith2 Marie-Claire ten Veldhuis et al.
  • 1Delft University of Technology, Watermanagement Department, Delft, 2628CN, the Netherlands
  • 2Princeton University, Hydrometeorology Group, Princeton, NJ 08544, USA
  • 3Tongji University, School of Ocean and Earth Science, Shanghai, 200092, China
  • 4UNEP-Tongji Institute of Environment for Sustainable Development Shanghai, Shanghai, 20002 China

Abstract. The impact of spatial and temporal variability of rainfall on hydrological response remains poorly understood, in particular in urban catchments due to their strong variability in land use, a high degree of imperviousness and the presence of stormwater infrastructure. In this study, we analyze the effect of storm scale, position and movement in relation to basin scale and flow-path network structure on urban hydrological response. A catalog of 279 peak events was extracted from a high-quality observational dataset covering 15 years of flow observations and radar rainfall data for five (semi)urbanized basins ranging from 7.0 to 111.1 km2 in size. Results showed that the largest peak flows in the event catalog were associated with storm core scales exceeding basin scale, for all except the largest basin. Spatial scale of flood-producing storm events in the smaller basins fell into two groups: storms of large spatial scales exceeding basin size or small, concentrated events, with storm core much smaller than basin size. For the majority of events, spatial rainfall variability was strongly smoothed by the flow-path network, increasingly so for larger basin size. Correlation analysis showed that position of the storm in relation to the flow-path network was significantly correlated with peak flow in the smallest and in the two more urbanized basins. Analysis of storm movement relative to the flow-path network showed that direction of storm movement, upstream or downstream relative to the flow-path network, had little influence on hydrological response. Slow-moving storms tend to be associated with higher peak flows and longer lag times. Unexpectedly, position of the storm relative to impervious cover within the basins had little effect on flow peaks. These findings show the importance of observation-based analysis in validating and improving our understanding of interactions between the spatial distribution of rainfall and catchment variability.

Short summary
The effect of storm scale and movement on runoff flows in urban catchments remains poorly understood due to the complexity of urban land use and man-made infrastructure. In this study, interactions among rainfall, urbanisation and peak flows were analyzed based on 15 years of radar rainfall and flow observations. We found that flow-path networks strongly smoothed rainfall peaks. Unexpectedly, the storm position relative to impervious cover within the basins had little effect on flow peaks.