Spatial and temporal variability of rainfall and their effects on hydrological response in urban areas – a review

Abstract

Abstract. In urban areas, hydrological processes are characterized by high variability in space and time, making them sensitive to small-scale temporal and spatial rainfall variability. In the last decades new instruments, techniques, and methods have been developed to capture rainfall and hydrological processes at high resolution. Weather radars have been introduced to estimate high spatial and temporal rainfall variability. At the same time, new models have been proposed to reproduce hydrological response, based on smallscale representation of urban catchment spatial variability. Despite these efforts, interactions between rainfall variability, catchment heterogeneity, and hydrological response remain poorly understood. This paper presents a review of our current understanding of hydrological processes in urban environments as reported in the literature, focusing on their spatial and temporal variability aspects. We review recent findings on the effects of rainfall variability on hydrological response and identify gaps where knowledge needs to be further developed to improve our understanding of and capability to predict urban hydrological response.

Effect of Temporal Resolution of Rainfall on Simulation of Urban Flood Processes

“…Variogram analysis was conducted theoretically to describe temporal (or spatial) variability as the characteristic scale, which was defined as the temporal (or spatial) distance by which two individual points show statistical independence [3]. Based on this method, Berne et al [10] proposed the relationship between the required characteristic scales of rainfall and urban catchments, and then derived the required rainfall resolution for urban hydrological applications.…”

“…In 1997, Singh [2] summarized how the hydrograph is affected by the temporal and spatial distribution of rainfall and identified that the influence of rainfall also depends on watershed characteristics. Rainfall variability makes it important to adopt an appropriate rainfall resolution to model hydrological response, especially in urban catchments with short response time [3,4]. In particular, for small urban catchments with drainage area no more than 10 km 2 , the temporal resolution of rainfall (TRR), rather than the spatial resolution of rainfall (SRR), has larger effect on hydrodynamic modelling [5,6].…”

Effects of variability in probable maximum precipitation patterns on flood losses

“…An important question concerns how the peak discharge and the volume of a flood depend on the intensity and track of the triggering precipitation events, i.e. the spatio-temporal pattern of precipitation (Adams et al, 2012;Bruni et al, 2015;Cristiano et al, 2017;Emmanuel et al, 2015Emmanuel et al, , 2016OchoaRodriguez et al, 2015;Paschalis et al, 2014;Rafieeinasab et al, 2015;Zhang and Han, 2017). In addition to the storm track dynamics, the peak flow depends on the watershed characteristics (Singh, 1997).…”

“…Furthermore, uncertainties in the economic models used to estimate flood losses and flood damages are relevant (de Moel et al, 2015). Herein, the input data, the choice of the impact indicators, the scale, and the vulnerability models are relevant sources of uncertainty (Ward et al, 2013;Apel et al, 2008;Merz and Thieken, 2009;de Moel and Aerts, 2011).…”

“…Herein, the input data, the choice of the impact indicators, the scale, and the vulnerability models are relevant sources of uncertainty (Ward et al, 2013;Apel et al, 2008;Merz and Thieken, 2009;de Moel and Aerts, 2011). In particular, vulnerability functions are considered as one of the most relevant sources of uncertainty in flood loss estimation (Ward et al, 2013;Sampson et al, 2014).…”