An assessment of the spatial and temporal distribution of natural hazards in Central Africa

2021 ◽  
Author(s):  
Giuliano Di Baldassarre

<p>Plinius (23-79 AD) is known worldwide as the author of the encyclopedic Naturalis Historia. He died in Stabiae while trying to rescue his family from the eruption of Mount Vesuvius, one of the deadliest volcanic eruptions in European history that also destroyed the cities of Herculaneum and Pompeii. At that time, natural hazards were mostly seen as “acts of God(s)”. Instead, in today’s Anthropocene, extreme events coexist with two dichotomic (and rather simplistic) views: “disasters are natural” vs. “humans are to blame since they live in risky areas”. In this lecture, I present scientific and societal challenges associated with the increasing impact (from Plinius’ time to the Anthropocene) of humans on the spatial and temporal distribution of natural hazards. I also problematize and challenge myths, preconceptions and conventional wisdoms related with uncertainty, behavioral heuristics, expert vs. local knowledge, social power and inequalities. To this end, I review recent studies in various socioeconomic contexts, and across multiple hazards, with a focus on five events that have significantly influenced my research work: the 1963 Vajont Dam landslide, the 2004 flooding in Haiti and the Dominican Republic, the 2009 L’Aquila earthquake, the water crisis (Day Zero) during the 2015-2017 drought in Cape Town and the ongoing COVID-19 pandemic.</p>


Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 351
Author(s):  
Adolfo Rosati ◽  
Damiano Marchionni ◽  
Dario Mantovani ◽  
Luigi Ponti ◽  
Franco Famiani

We quantified the photosynthetically active radiation (PAR) interception in a high-density (HD) and a super high-density (SHD) or hedgerow olive system, by measuring the PAR transmitted under the canopy along transects at increasing distance from the tree rows. Transmitted PAR was measured every minute, then cumulated over the day and the season. The frequencies of the different PAR levels occurring during the day were calculated. SHD intercepted significantly but slightly less overall PAR than HD (0.57 ± 0.002 vs. 0.62 ± 0.03 of the PAR incident above the canopy) but had a much greater spatial variability of transmitted PAR (0.21 under the tree row, up to 0.59 in the alley center), compared to HD (range: 0.34–0.43). This corresponded to greater variability in the frequencies of daily PAR values, with the more shaded positions receiving greater frequencies of low PAR values. The much lower PAR level under the tree row in SHD, compared to any position in HD, implies greater self-shading in lower-canopy layers, despite similar overall interception. Therefore, knowing overall PAR interception does not allow an understanding of differences in PAR distribution on the ground and within the canopy and their possible effects on canopy radiation use efficiency (RUE) and performance, between different architectural systems.


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