Scientists at the National Space Research and Development Agency, Nigeria have evolved new technique for estimating population growth of areas using high resolution satellite image of NigeriaSat-2. The technique called Dasymetric, according to Dr. Halilu Shaba, Director, Strategic Space Application Department, relies on remote sensing method and property information model to identify where people live at a regional, national or local level by practically relating satellite and land use data on geographical maps.
The use of space technology for mapping activities has over the years gained prominence in the developed and developing countries of the world. This is because it has proved to alleviate the tedious tasks of conventional survey approach, accessibility to remote areas, as well as having the synoptic view of settlements, he said.
The need to know how many Nigerians, despite various attempts, has remained a difficult nut to crack. Yet population figures are necessary for planning purposes on a daily basis. Nigeria’s last census was in 2006. Even if censuses were to be regular, its nature being decennial demands the development of population estimation techniques to provide up-to-date population figures.
Therefore, the launch and availability of NigeriaSat-1, NigeriaSat-2 and NigeriaSat-X, have made it possible to carry out a comprehensive survey covering the entire country as often as desired. As such, the repetitive nature of satellite makes it particularly suitable for timely generation of data by providing a ready and steady streams of inter-censal population estimation which hitherto had relied mainly on the irregular censuses that we have had in Nigeria.
While different techniques have been explored over the years to estimate population changes, in dasymetric mapping, urban phenomenon are examined differently from the rural phenomenon because they both exhibit different characteristics in terms of population ratios such as age demographics; this is also because there are different changing processes and activities happening in the urban area compared to the rural area.
One of the major challenges highlighted during the course of the project was that Population data from the state level down to ward level was not available; this necessitated the need to conduct a proper field work. During the field work again, housing data that was needed to support smooth data collection was not also readily available. Also the satellite images that were available for the project activity are obsolete images, which would have helped to provide an up-to-date accuracy.
Without accurate figures, planning becomes defective because the population figures that provide useful guide more often than not are based on assumptions and estimates depending on the user.
According to Dr. Halilu Shaba, the use of maps in demographic analyses is becoming almost inevitable especially when assessing spatial aspects of demographic changes and movements and their interactions with the environment.
In Abuja, where a pilot project was carried out, is Nigeria’s major administrative metropolitan city that is characterized with high immigration of people from different parts of the country, this push-in factor has led business people and the younger generation to migrate in search of better employment opportunities, improved economic development, and better qualitative professional development.
Over the years, indeed between 1963 and 1991 and 2006 to-date Nigeria’s population has been extrapolated based on estimates and assumed rates of growth. The study provide baseline information and procedure, which relevant agencies and stakeholders can use in generating inter-censal population data for planning purposes.
Remote sensing technology is a veritable tool that has been found useful in many advanced countries in census planning. Now is the time for Nigeria to take full advantage of the technology, particularly based on the availability of data from NigeriaSat-1, 2 and X in her effort to cultivate a culture of generating accurate, reliable and acceptable population figures for the country.