Reconstruction of a Storm Map and New Approach in the Definition of Categories of the Extreme Rainfall, Northeastern Sicily

Francesco Fiorillo,Massimiliano Meo,Nazzareno Diodato

doi:10.3390/w8080330

Abstract

After more than 350 mm of rainfall fell in a few hours on 22 November 2011, thousands of landslides and floods were induced in two main zones of Northeastern Sicily. The total rainfall has been reconstructed integrating available rain gauge data with Tropical Rainfall Measuring Mission (TRMM) satellite data from NASA (National Aeronautics and Space Administration); the landslide distribution in the field has confirmed the pattern of rainfall accumulated on 22 November 2011. Precipitation maxima of 1, 3, 6, 12, and 24 h was recognized as the hazardous events, which marks the evidence of a changing climate, with a shift toward more intense rainfalls in recent times. To investigate the sequence of the annual maxima, the historical time series have been transformed in the Standard normal distribution, from the cumulative probability of the GEV (Generalized Extreme Value) distribution. Following a similar definition of the Standard Precipitation Index (SPI), the transformation of the historical data in the standardized values allows the definition of categories of hourly maxima in term of extreme, severe, moderate, or mild. This transformation allows to eliminate the asymmetry of the time series, so that trends and fluctuations have been highlighted by the progressive accumulation of data (Rescaled Adjust Partial Sum). This statistical approach allows the improvement of the interpretability of the hydrological extreme events, and could also be used in other cases.

Highlights

Despite hydroclimate millennia reconstruction not supporting a general unprecedented intensification of the Northern Hemisphere hydrological cycle in the twentieth century associated with both more extreme wet and dry conditions [1], rainstorms and their injuries are becoming more dangerous as population and infrastructure continue to increase and to occupy areas exposed to flood risk [2,3]
To reconstruct a more likely spatial distribution of rainfall occurring on 22 November 2011, gauge density has been integrated with data recorded from the Tropical Rainfall Measuring Mission rain gauge density has been integrated with data recorded from the Tropical Rainfall Measuring satellite (TRMM)
On the network formed by rain gauges and TRMM points, a new spatial rainfall distribution has been mapped by formed by rain gauges and 8TRMM

Summary

Introduction

Despite hydroclimate millennia reconstruction not supporting a general unprecedented intensification of the Northern Hemisphere hydrological cycle in the twentieth century associated with both more extreme wet and dry conditions [1], rainstorms and their injuries are becoming more dangerous as population and infrastructure continue to increase and to occupy areas exposed to flood risk [2,3]. Few literature sources are available worldwide regarding extreme precipitation and, especially, about rainstorm effects on regional and subregional terrestrial ecosystems and water resources [4,5,6,7]. This poses another question related to the development of dynamic hydrological models, hampered by incomplete understanding of spatially-varying processes and the lack of adequate datasets to spatially characterize varying rain inputs. Water 2016, 8, 330; doi:10.3390/w8080330 www.mdpi.com/journal/water rainstorm rainstorm patterns patterns with with marked marked inter-annual inter‐annual variability variability expose expose landforms landforms to to exacerbated, exacerbated, damaging damaging hydrological processes [9,10,11,12]. This is so to spur the emergence of new hazards, such such as as coastal coastal and and urban urban flooding flooding [13,14]

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Conclusion