It is very important for urban climatologists to consider the heat balance at the urban area surface in order to understand the mechanisms of the urban climate. One of the questions is whether the ...surface albedo of urban areas is higher or lower compared with that of the suburbs. A model is developed for an urban area with a grid pattern network of roads and cubic buildings, the surface microstructure of which can be expressed in terms of both the building-land ratio in the total model area and the sky view-factor at the center of the intersection of the model. A technique is also developed to simulate their upward reflected radiance or albedo as a function of the surface structure and the solar elevation when the solar illumination direction is parallel to and at an angle of 45 degrees with the street canyon. In the simulation, the incoming solar radiation is divided into two components, i. e., direct and diffuse radiations, and the amount of upward reflected radiance is formed by four components : primary reflection from the roof, and from primary through tertiary reflections from the canyon floor. It is assumed in this simulation that all the facets of urban area surface are Lambertian, and that all the components of shortwave radiation are isotropic, exclusive of direct solar radiation. Results from simulation show that the upward reflected radiance, i.e., albedo also, depends clearly upon the building-land ratio, the sky view-factor and the solar elevation: The urban surface albedo is relatively high in both extremely high and low building-land ratio regions, although it is significantly decreased in the middle building-land ratio region. In addition, it is more sensitive to the decreases in the sky view-factor and solar elevation in such a region. The above effects are more significant when the solar illumination direction is at an angle of 45 degrees with the street canyon than when the solar illumination is parallel to the street canyon. A comparison of satellite-derived albedos in the Kanto Plain on November 5, 1990, by Nakagawa and Nakayama (1995) with the simulated cases in this study confirms that the simulated results by the model, in which the solar illumination direction is at an angle of 45 degrees to the street canyon, are in good agreement with the field measurements, instead that the urban structure of the model is not realistic and the albedos of their facets are assumed to be the same. These facts mean that, if the albedos of all elements of the urban area surface are the same, the albedo of the urban area is decreased as the building-land ratio reaches the middle range and the sky view-factor is decreased, and that this results from trapping of direct solar radiation illuminating the sunny walls in the urban canyon, which would illuminate the canyon floor that is shadowed by obstructions.
The dependence of surface albedo on surface structure is investigated in the central parts of 23 urban areas in the Kanto Plain, Japan. The surface albedo is inferred from LANDSAT/MSS data collect-ed ...on 5 November 1990, using Nakagawa and Ooi's (1992) method. The surface structure in the cen-tral part of the urban area is measured in terms of both sky view-factor and building-land ratio, which are regarded as substitutions for Aida and Gotoh's (1982) .parameters H/Wf and Wr/Wf respec-tively. As a result, it is found that the surface albedo is relatively high in cases of remarkably high or low building-land ratios, and that the surface albedo clearly decreases with decreasing sky view-factor. It is also found that the surface albedo in the central part of the urban area clearly decreases with increasing daytime population density. The dependencies of surface albedo both on surface struc-ture and on daytime population density of urban area are derived from the clear dependence of sur-face structure parameters of the central part of the urban area on its daytime population density.
The quest for building lands near Cotonou by city dwellers has provoked a deep transformation of Godomey, a small municipality, founded in the 18th century, located at about 10 kilometres, west of ...town, and inhabited by ancient families, traditional owners of large areas of land. To meet their need for money, they started selling their isolated land in small portions. The new owners build city type houses.
Thus two kinds of landscape can be observed : an initial nucleus of old-fashioned houses and winding paths for pedestrians and cyclist. Around those are quarters where built or bare enclosures spread untidy. Their owners live on work in Cotonou for most them and have a style of which typically urban.
There is no doubt that Godomey is setting rapidly urbanised ; but is retructuring which will come about eventually will pose serious problems.
La recherche par les citadins de terrains à bâtir, à proximité de Cotonou, a entraîné une profonde transformation de Godomey, petite bourgade fondée au XVIIIe siècle, située à une dizaine de kilomètres à l'ouest de la ville, et habitée par de vieilles familles propriétaires traditionnelles de grandes étendues de terre. Pour satisfaire leurs besoins monétaires, celles-ci se sont mises à vendre des parcelles isolées ou par petits lots, sur lesquelles les acheteurs bâtissent des maisons modernes, de type urbain.
Deux types de paysages apparaissent : un noyau initial de vieux quartiers, aux maisons anciennes de taille modeste, entre lesquelles serpentent des sentiers pour piétons et cyclistes ; des quartiers périphériques, où les parcelles encloses, bâties ou non, se disposent souvent dans le désordre, et dont les propriétaires résident ou travaillent pour la plupart à Cotonou ; ils mèneht un genre de vie typiquement urbain. Il est évident que Godomey est en voie d'urbanisation rapide, mais sa restructuration, inévitable à terme, posera de difficiles problèmes.
N'Bessa Benoît. Espaces péri-urbains et problèmes fonciers : le cas de Godomey, à l'ouest de Cotonou (Bénin). In: La péri-urbanisation des les pays tropicaux. Bordeaux : Presses Universitaires de Bordeaux, 1989. pp. 99-112. (Espaces tropicaux, 1)
The quick growth of Cotonou and Porto-Novo had led to a high demand for building plots of land and a continuous increase of their price over the last twenty years. The concept of family land ...ownership existed in the southern part of Benin before colonisation came to reinfurce it by introducing official registration of land. Big land owners make money by selling building plots which gives rise to not planned and unequipped outhying districts.
A state town planning company, known as SONAGJM has been trusted with the responsability of putting some order in that chaos. After an inventory of fixtures, an official allotment of real estate is established. When this is approved of, new plots of land are distributed to furned occupants in proportion with the size of the land they owned before, and taking account of the need of space for other urban networks.
As result of this work those plats take on an increased value which favours an active land purchase business speculation, done with the tadt complicity everyone and profiting those with high income.
It is paradoxical that state intervention in a country with a sodalist option should result into high profit for private indivuals.
La croissance rapide de Cotonou et de Porto-Novo a entraîné une demande élevée de terrains à bâtir, et une hausse permanente du prix des parcelles au cours des 20 dernières années. Au sud du Bénin, la notion de propriété familiale du sol existait avant la colonisation, et celle-ci l'a consolidée en introduisant l'immatriculation officielle des terres. Les possesseurs de surfaces étendues se procurent aujourd'hui de l'argent en vendant des parcelles, ce qui provoque la formation anarchique de quartiers périphériques non équipés.
L'Etat confie à la SONAGIM (Société Nationale de Gestion Immobilière) le soin de régulariser la situation. Après un inventaire ("état des lieux"), un lotissement officiel est établi, qui, après approbation, permet une redistribution de nouvelles parcelles aux anciens occupants, en fonction des surfaces qu'ils possédaient jusque-là, et l'équipement du quartier en voirie et réseaux divers, et en bâtiments publics. Mais de ce fait, les terrains acquièrent une plus-value considérable, et ce phénomène est à l'origine d'une active spéculation foncière, qui se pratique avec la complicité tacite de tout le monde, et profite naturellement surtout à ceux qui disposent de revenus élevés. Le paradoxe est que dans un pays dont l'option politique est résolument socialiste, l'intervention de l'Etat est génératrice de bénéfices élevés pour des particuliers...
N'Bessa Benoît,Okou Christophe,Tossa Jacob T.,Vennetier Pierre. Formation de l'espace urbain et intervention de l'Etat : le paradoxe béninois. In: La péri-urbanisation des les pays tropicaux. Bordeaux : Presses Universitaires de Bordeaux, 1989. pp. 77-88. (Espaces tropicaux, 1)
sisällön kuvaus: Hermanni, Toukola, Arabianranta. Näkymä Vanhankaupunginlahden rannalta Hermannin suunnalta Arabianrantaan päin. Etualalla täyttömaata ja lintuja lahden yllä. Taustalla mm. Wärtsilä ...Oy:n Arabian tehdas sekä Vanhankaupunginkosken rakennuksia.
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Content description: Hermanni, Toukola, Arabianranta. View from the Old Town Bay from Hermann to Arabianranta. Filling land and birds above the bay. In the background e.g. Wärtsilä Oy’s Arabian factory as well as buildings in the Old Town rapids.
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