Historical predictability of rainfall erosivity: a reconstruction for monitoring extremes over Northern Italy (1500\u20132019)

Nazzareno Diodato,Fredrik Charpentier Ljungqvist,Gianni Bellocchi

doi:10.1038/s41612-020-00144-9

Abstract

Erosive storms constitute a major natural hazard. They are frequently a source of erosional processes impacting the natural landscape with considerable economic consequences. Understanding the aggressiveness of storms (or rainfall erosivity) is essential for the awareness of environmental hazards as well as for knowledge of how to potentially control them. Reconstructing historical changes in rainfall erosivity is challenging as it requires continuous time-series of short-term rainfall events. Here, we present the first homogeneous environmental (1500–2019 CE) record, with the annual resolution, of storm aggressiveness for the Po River region, northern Italy, which is to date also the longest such time-series of erosivity in the world. To generate the annual erosivity time-series, we developed a model consistent with a sample (for 1981–2015 CE) of detailed Revised Universal Soil Loss Erosion-based data obtained for the study region. The modelled data show a noticeable descending trend in rainfall erosivity together with a limited inter-annual variability until ~1708, followed by a slowly increasing erosivity trend. This trend has continued until the present day, along with a larger inter-annual variability, likely associated with an increased occurrence of short-term, cyclone-related, extreme rainfall events. These findings call for the need of strengthening the environmental support capacity of the Po River landscape and beyond in the face of predicted future changing erosive storm patterns.

Highlights

Hydrological extremes[1,2,3] are an important component of climate variability and are partly governed by ocean dynamics[4]
Greater awareness on the temporal variability of storm erosivity is important as it has implications for the understanding of geomorphological dynamics such as erosional soil degradation[11] and other landscapes stresses like flash-floods and surface landslides[12]
Erosive storm events usually result in accelerated soil erosion[18,19] and mud floods in urban areas[20,21], and the consequences can be severe in terms of reduced socio-economic sustainability[22,23,24]

Summary

Introduction

Hydrological extremes[1,2,3] are an important component of climate variability and are partly governed by ocean dynamics[4]. For the reconstruction of annually resolved storm erosivity (MJ mm ha−1 h−1 yr−1) for the PRL, we developed and calibrated the Rainfall Erosivity Historical Model (REHM, Eq (1)), based on

Results

Conclusion