Temperature effects on the spatial structure of heavy rainfall modify catchment hydro-morphological response

Abstract

Abstract. Heavy rainfall is expected to intensify with increasing temperatures, which will likely affect rainfall spatial characteristics. The spatial variability of rainfall can affect streamflow and sediment transport volumes and peaks. Yet, the effect of climate change on the small-scale spatial structure of heavy rainfall and subsequent impacts on hydrology and geomorphology remain largely unexplored. In this study, the sensitivity of the hydro-morphological response to heavy rainfall at the small-scale resolution of minutes and hundreds of metres was investigated. A numerical experiment was conducted in which synthetic rainfall fields representing heavy rainfall events of two types, stratiform and convective, were simulated using a space-time rainfall generator model. The rainfall fields were modified to follow different spatial rainfall scenarios associated with increasing temperatures and used as inputs into a landscape evolution model. The experiment was conducted over a complex topography, a medium-sized (477 km2) Alpine catchment in central Switzerland. It was found that the responses of the streamflow and sediment yields are highly sensitive to changes in total rainfall volume and to a lesser extent to changes in local peak rainfall intensities. The results highlight that the morphological components are more sensitive to changes in rainfall spatial structure in comparison to the hydrological components. The hydro-morphological features were found to respond more to convective rainfall than stratiform rainfall because of localized runoff and erosion production. It is further shown that assuming heavy rainfall to intensify with increasing temperatures without introducing changes in the rainfall spatial structure might lead to overestimation of future climate impacts on basin hydro-morphology.

Modelling impacts of spatially variable erosion drivers on suspended sediment dynamics

“…This finding also suggests that a large proportion of the sediment yield can be supplied by just few localized sediment sources (e.g. Pelletier, 2012). The role of soil moisture in producing high sediment concentrations has also been highlighted by Dominic et al (2015) and Brasington and Richards (2000), who attribute the peaks of SSCs to the connection of remote sediment sources during the wetting up of a catchment.…”

“…CAESAR-Lisflood (Coulthard et al, 2013), and SIBERIA (Hancock et al, 2000), or some largescale sediment flux models, e.g. WBMsed (Cohen et al, 2013) and Pelletier (2012). More suitable approaches are tRIBS (Francipane et al, 2012), which includes a physically based hydrological component suitable for long-term process simulations, and DSHVM (Doten et al, 2006), which features a detailed hydrology-vegetation component and sediment module.…”

The impact of different rainfall products on landscape modelling simulations

“…First, as discussed above, they currently do not make use of probabilistic methods to assess uncertainty. Second, the models display far greater sensitivity to the rainfall input with regard to the choice of product (this study), resolution of the data (Coulthard and Skinner, 2016), and changes to the storm structure (Peleg et al ., 2020b). Third, geomorphic models retain a ‘memory’ of past events in a way hydrological models do not, where an erroneous change to the landscape is retained and will influence all future outputs.…”

“…It has been applied for several hydrological applications (e.g. over a large rural catchment for flood investigations – Paschalis et al ., 2014, to simulate extreme rainfall intensity over small scales – Peleg et al ., 2018, and to study the impacts of spatial and climatological rainfall variability in urban drainage – Peleg et al ., 2017a), and was applied with the CAESAR‐Lisflood model to study the landscape sensitivity to extreme rainfall events in the context of climate change (Peleg et al ., 2020b). STREAP reproduces the storm arrival process (i.e.…”

Spatio-Temporal Analysis of Intense Convective Storms Tracks in a Densely Urbanized Italian Basin

“…Among all the drivers that concur in the formation of such convective events, the temperature has a key role [16,17]. For this reason, global warming caused by climate change [18][19][20][21][22][23][24] could potentially strongly affect the behavior of such storms.…”