The 20 February 2010 Madeira flash-floods: synoptic analysis and extreme rainfall assessment

Abstract

Abstract. This study aims to characterise the rainfall exceptionality and the meteorological context of the 20 February 2010 flash-floods in Madeira (Portugal). Daily and hourly precipitation records from the available rain-gauge station networks are evaluated in order to reconstitute the temporal evolution of the rainstorm, as its geographic incidence, contributing to understand the flash-flood dynamics and the type and spatial distribution of the associated impacts. The exceptionality of the rainstorm is further confirmed by the return period associated with the daily precipitation registered at the two long-term record stations, with 146.9 mm observed in the city of Funchal and 333.8 mm on the mountain top, corresponding to an estimated return period of approximately 290 yr and 90 yr, respectively. Furthermore, the synoptic associated situation responsible for the flash-floods is analysed using different sources of information, e.g., weather charts, reanalysis data, Meteosat images and radiosounding data, with the focus on two main issues: (1) the dynamical conditions that promoted such anomalous humidity availability over the Madeira region on 20 February 2010 and (2) the uplift mechanism that induced deep convection activity.

A dependence modelling study of extreme rainfall in Madeira Island

“…The island has a near EeW oriented orographic barrier, approximately perpendicular to the prevailing N-SE wind direction, which induces a remarkable variation of rainfall between the northern and southern slopes (Fragoso et al, 2012). Madeira Island's mountain ridge located along its central part presents Pico Ruivo, the highest peak with 1861 m, and Pico do Areeiro, with 1818 m, in its eastern part, while Paul da Serra massif is located above 1400 m in the western part of the island.…”

“…However, in 1990, some stations would no longer be functioning, others would provide data only concerning to the prevailing wind direction and intensity and other stations ceased to be maintained by JGDAF. Nowadays Madeira Island is covered by rain gauge stations maintained by three different institutions, namely the Madeira's Investments and Water Management (IGA) company, the Portuguese Institute for Sea and Atmosphere (IPMA), and the Madeira Regional Laboratory of Civil Engineering (LREC) (Fragoso et al, 2012). As referred before, the data used in this study correspond to maximum annual rainfall records from 12 rain gauge stations distributed over the island.…”

“…Other southern areas like Machico, Santa Cruz, Campanario, Ribeira Brava and Calheta were also affected by this devastating event. In the last century, six catastrophic rainfallinduced events were registered in Madeira, namely in 1920Madeira, namely in , 1929Madeira, namely in , 1956Madeira, namely in , 1979Madeira, namely in , 1993Madeira, namely in and 1997, totaling more than 60 deaths and several dozens of injured people and houses destroyed (see, e.g., Baioni, 2011;Fragoso et al, 2012;Quintal, 1999). More recently, already in the 21st century, two significant events of this type were registered in Madeira Island, the first in March 2001, with five deaths and material damages of several tens of million euros (Rodrigues and Ayala-Caicedo, 2003), and the second one in February 2010, which caused 45 casualties, six missed people, more than a hundred injured and about 1.4 billion euros of material losses (Baioni, 2011;Fragoso et al, 2012), which indicate an increase in the frequency of such events and in the damage caused by them.…”

“…In the last century, six catastrophic rainfallinduced events were registered in Madeira, namely in 1920Madeira, namely in , 1929Madeira, namely in , 1956Madeira, namely in , 1979Madeira, namely in , 1993Madeira, namely in and 1997, totaling more than 60 deaths and several dozens of injured people and houses destroyed (see, e.g., Baioni, 2011;Fragoso et al, 2012;Quintal, 1999). More recently, already in the 21st century, two significant events of this type were registered in Madeira Island, the first in March 2001, with five deaths and material damages of several tens of million euros (Rodrigues and Ayala-Caicedo, 2003), and the second one in February 2010, which caused 45 casualties, six missed people, more than a hundred injured and about 1.4 billion euros of material losses (Baioni, 2011;Fragoso et al, 2012), which indicate an increase in the frequency of such events and in the damage caused by them. This emphasize the need for appropriate statistical models of extreme hydrological events, particularly in the current context of global and regional climate and environmental changes, since the modelling of extreme rainfall has an important role in the design of water-related structures, in rural and agricultural engineering, and in many other areas, such as civil defense, where the hydrological monitoring and the knowledge concerning weather and climate extremes are fundamental.…”

Using modeling tools for implementing feasible land use and nature conservation governance systems in small islands – The Pico Island (Azores) case-study

“…This is due to the higher susceptibility and vulnerability of these territories to ecological disturbances (e.g. Pelling and Uitto, 2001;Calado et al, 2011;Fragoso et al, 2012;Nunn and Carson, 2015), the lower resilience of the islands limited species number and gene pool and, consequently, the higher levels of extinction debt (Frankham, 1998;Ricketts et al, 2005;Triantis et al, 2010;Mora et al, 2012). These problems imply management approaches able to combine human aspirations with the preservation of viable ecological communities and the prevention of invasion by alien species, ensuring simultaneously higher ecosystem resilience (Craig, 1990;Daugherty et al, 1990;Francisco-Ortega et al, 2000;Lane, 2007;Reaser et al, 2007;Caujap e-Castells et al, 2010).…”