Interactions between rainfall spatial distribution and flow path network structure in relation to urban hydrological response

Abstract

In this study, the interaction between rainfall spatial distribution and flow path network structure in relation to
hydrological response was analysed based on 15 years of flow observations for five (semi)urbanised basins ranging
from 7.0 to 111.1 km2 in size. We use the concept of rainfall-weighted flow distance to look into the effect of
rainfall spatial concentration in relation to the drainage network. Results show that for the majority of events,
rainfall spatial variability and rainfall-weighted flow distance variability are uncorrelated, showing that the flow
path network clearly alters the way spatial rainfall variability affects hydrological response in these basins. The
flow path network leads to strong smoothing of spatial rainfall variability, increasingly so for larger basin size.
Correlation analysis shows that mean rainfall-weighted flow distance is significantly correlated with flow peak
in some of the basins, while there is no significant correlation with lag time. Storm movement in relation to the
flow path network is investigated based on time changes in rainfall-weighted flow distance. Results show that the
direction of storm movement does not seem to play a significant role, while storm movement velocity does have
an influence on lag time and flow peaks, under certain conditions.