Sahara

Summary

The Sahara (səˈhɑːrə, səˈhærə) is a desert on the African continent. With an area of , it is the largest hot desert in the world and the third-largest desert overall, smaller only than the deserts of Antarctica and the northern Arctic. The name "Sahara" is derived from the Arabic word for "desert" in the feminine irregular form, the singular (صحراء //ˈSaHra), plural (صَحَارَى //ˈSaHaaraa), (صَحَار), (صَحْرَاوَات), (صَحَارِي). The desert covers much of North Africa, excluding the fertile region on the Mediterranean Sea coast, the Atlas Mountains of the Maghreb, and the Nile Valley in Egypt and the Sudan. It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean in the west, where the landscape gradually changes from desert to coastal plains. To the south it is bounded by the Sahel, a belt of semi-arid tropical savanna around the Niger River valley and the Sudan region of sub-Saharan Africa. The Sahara can be divided into several region

Official source

https://en.wikipedia.org/wiki/Sahara

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Constructing the desert. Hotel and coach station (Ouarzazate, Maroc)

Pietro Berta, Adèle Moret

Desertification process keeps on expanding, particularly on the African continent, arid areas cover one third of the surface. At the same time, the world human population increases exponentially. For these reasons, it is important to keep on exploiting these desert zones. Ouarzazate is situated in the south of Morocco in a sub-desert climate. The city is nicknamed “Door of the desert” because of its strategic location: it is situated at the junction of the two roads, which give accessibility to the south of Morocco and the Sahara desert. The region is well known for its architectural patrimony and more recently for the cinema activities. These two different domains make increase the number of visitors in this part of the country and there will soon be a lack of host infrastructure including hotels. The project, a hotel and a coach station, doesn't want to be closed-off on itself, but to take place in the city centre to benefit of the existing activities; at the same time the two programs are close to the main crossroad of the region. This situation is accorded with the way tourists travel in the region: moving a lot in order to discover a maximum of sites spread in the south and staying a short time in the same place. The hotel is inspired by the caravanserai, which was a roadside inn along the trade routes where travellers could rest and recover from the day's journey. It supported the flow of commerce, information and people. It was a place where travellers could acquire new supplies and there were also shops where merchants could dispose of some of their goods. The issue of this project in the desert is to build in a sustainable way using contemporary building construction modes being in the same time inspired by vernacular architecture.

2009

Resources both physical and financial are scarce in most developing countries while environmental concerns are growing requiring a greater effort to rationally plan investments. Nowadays the methods for designing, planning and managing integrated energy systems, while holistically considering the major economic and environmental factors, are still embryonic. However, the first phase of the design is often crucial if we want to aim at a better resource management and at the reduction of energy consumption together with reduced environmental impact. Considering integrated energy systems implies dealing with complex systems in which the synergy between the various components is exploited at best. The context of isolated communities further increases the difficulties when considering the long distance of transportation required to supply fossil fuels, the constraints of not being connected to a national network and the locations in very precarious environments, with limited or inexistent resources except for solar. This paper illustrates a holistic method to rationalize the design of energy integrated systems accounting for Life Cycle Analysis parameters (CST method). It is based on a superstructure (collection of models of all envisaged technologies) using a multi-modal and multi-objective evolutionary algorithm. The models include both solar power technologies as well as conventional Diesel electric generators. The approach is applied to the supply of energy services to an oasis in the Sahara desert. The study shows that the economic implementation of renewable energy (solar) is even more difficult, compared to Diesel based solutions, in cases of isolated communities with high load variations.

2007

Primary productivity of continental and marine ecosystems is often limited or co-limited by phosphorus. Deposition of atmospheric aerosols provides the major external source of phosphorus to marine surface waters. However, only a fraction of deposited aerosol phosphorus is water soluble and available for uptake by phytoplankton. We propose that atmospheric acidification of aerosols is a prime mechanism producing soluble phosphorus from soil-derived minerals. Acid mobilization is expected to be pronounced where polluted and dust-laden air masses mix. Our hypothesis is supported by the soluble compositions and reconstructed pH values for atmospheric particulate matter samples collected over a 5-yr period at Finokalia, Crete. In addition, at least tenfold increase in soluble phosphorus was observed when Saharan soil and dust were acidified in laboratory experiments which simulate atmospheric conditions. Aerosol acidification links bioavailable phosphorus supply to anthropogenic and natural acidic gas emissions, and may be a key regulator of ocean biogeochemistry. © 2011 Author(s).

2011