Dasymetric Mapping as a Tool to Assess the Spatial Distribution of Population in Jeddah City (Kingdom of Saudi Arabia)

Abstract

It is well-known that, when dealing with density of population, most of the proposed maps choose the easiest and probably the most understandable cartographic method, i.e. the choropleth method. Nevertheless, for heterogonous spaces and those observing intense spatial dynamic, it is proven that this method has many lacks and deficiencies. This is the case of Jeddah city (the second largest city in Saudi Arabia), which is a very contrasted urban place with regards to its social structure, spatial organization and land use besides the fact that it witnesses a profound and continuous urban growth. Yet, most of the planning decisions are often taken on these types of maps and may mislead the urban planners. In this context, the dasymetric maps reveal very useful because they may give the real distribution of the population. Therefore, we think that establishing a dasymetric map at a convenient scale with regards to the results of satellite image processing may help the planners and the geographers as well as the common users. Indeed, this method may be an interesting alternative to the classic choropleth map. First it may improve our estimations towards the density within the various areas of the districts. Second it may refine the original enumeration units often using the administrative apportionment and therefore help the planning and agricultural agencies when establishing their base maps. The satellite image processing and GIS were used as tools in this study.