ABSTRACT

The possibility of using high resolution satellite data on a GIS platform for fast and low-cost map upgrading and digital cartographic database-building over remote areas in Africa is demonstrated. Using just one LANDSAT TM composite image, in combination with DEM (digital elevation model) and the author’s GPS data, a series of base and derived maps (hydrography, territorial boundaries, villages location, road network, relief) was obtained in a digitized, highly accurate, updated and upgradeable GIS-friendly format for the remote Kayamba Chiefdom in Congo. From these digital layer maps, a set of quantitative cartographic metrics (coordinates, distance, length, area, slope, aspect, etc.) was reliably deduced. All these fi ndings provide a solid base for further quantitative eco-climatic analysis or land/resources management and planning for the Chiefdom. Ground truth data are determinant in defi ning and/or identifying the surface features embedded in the satellite imagery. I recommend this analysis approach for those remote areas in developing countries where a full-scale ground survey is too costly or technologically too demanding.

Abstract: This study represents a part of an ongoing research program to evaluate the lithologic mapping capabilities of NigeriaSat-1. Rafin Gabas is located in Nasarawa state and falls within the Younger Granite province of Nigeria. Wolframite and cassiterite have been found to occur within this area.The topographical map of the study area was generated from the SRTM (Shuttle Radar Topography Mission Data). The DEM was converted into a contour map using the ERDAS and ArcView softwares. The NigeriaSat-1 image of the area was subjected to various image processing techniques such as edge enhancement, Principal component analysis and filtering. Samples from wolframite-bearing-quartzite-veins were analysed and old tin mines were studied. The various ancillary data were integrated in ILWIS software. Geological information such as lithological boundaries and lineaments were derived from the NigeriaSat-1 image. The lineaments were found to occur in the NE-SW direction and they range in length from 300 Km to 2.5 Km and some cut across rock boundaries. The results of the XRF analysis show an average of 62% Wo . Tailings from the old mines were observed to 3 contain some amounts of Cassiterite which could be reworked. The various data generated were integrated in a GIS environment and a mineral probability map was produced.

European Digital Archive of Soil Maps

Introduction

“Data and information are essential building blocks of science. Many types of data, including extant historical data which have newly appreciated scientific importance for the analysis of changes over time, are not being used for research because they are not available in digital formats” (International Council for Science, 2004).

Display Maps