Interplay Between Event Frequency and Intensity in Future Rainfall Erosivity revealed by Convection-permitting climate models

Authors:

Ezeaba Assumpta¹, Dallan Eleonora¹, Vohnicky Petr¹, Borga Marco¹

¹ Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro, Italy

Type of presentation:

Poster

 

Title:

Interplay Between Event Frequency and Intensity in Future Rainfall Erosivity revealed by Convection-permitting climate models

 

Abstract:

Soil erosion represents a critical environmental and economic challenge facing agricultural landscapes, and its severity could be amplified by the rising intensity of extreme rainfall in a warming climate. Rainfall erosivity, a key driver of erosion, depends on both rainfall intensity and the frequency of erosive events, making it highly sensitive to their ongoing and future changes. High resolution convection-permitting models (CPMs) offer enhanced representation of sub-daily rainfall extremes, yet their application to soil erosion studies remains limited.

This work assesses the skill of an hourly CPM in reproducing historical rainfall erosivity in a Mediterranean Island, Sicily, and evaluates its future changes under RCP4.5 and RCP8.5 scenarios. Modelled rainfall was first bias-corrected using intensity thresholds and scaling factors derived from high temporal-resolution observations. The CPM shows underestimate in maximum rainfall intensity and erosive event frequency, and thus in mean annual erosivity, especially in lowland and coastal areas. These biases highlight challenges in simulating short-duration convective events, sea-land interactions, and mismatches between point-based and gridded datasets. Future projections show divergent outcomes: under RCP4.5 moderate frequency decrease combines with higher intensities leading to a moderate net increase in erosivity, whereas under the RCP8.5 scenario a marked (17%) reduction in event frequency dominates the signal, yielding lower future erosivity despite rainfall intensification.

The results demonstrate that bias correction procedures should consider topographic dependence and different erosivity-related variables, and that future erosivity cannot be inferred from intensity changes alone; event frequency is equally relevant. Incorporating high-resolution climatic models and explicitly accounting for frequency-intensity interactions are therefore essential for robust erosion risk assessments and climate adaptation strategies.

 

This study was carried out within the RETURN Extended Partnership and received funding from the European Union Next‐GenerationEU (National Recovery and Resilience Plan—NRRP, Mission 4, Component 2, Investment 1.3—D.D. 1243 2/8/2022, PE0000005); and within the Space It Up project funded by the Italian Space Agency, ASI, and the Ministry of University and Research, MUR, under contract n. 2024-5-E.0 - CUP n. I53D24000060005.