Obtaining digital geological map from satellite images : case study Al-Abyad area-Kordufan-Sudan

الملخص EN

The great development that has occurred in recent decades in remote sensing has enabled obtaining satellite images of high-resoluton.

Those images illustrate the reality of the Earth's surface in a way enables extraction of many useful and necessary maps and data for various purposes inducing geological maps wt*ch arc the cornerstone of various Strategic Judies, such as mineral exploration, engineering projects and hydrogeological Studies and so on.

In order to check the geological map of Al-Abyad area in Kordofan m Sudan and raise its accuracy, satellite images from the Sentilnel-2 and Landsat-8 were used to derive the geological map of the Sludy area.

The resulted geological map is compatible with the paper geological maps of the area.

The high accuracy of the derived map enabled drawing detailed boundaries for various outcrops of deferent geological formations in the area.

By visual interpretation, regions of interest (ROI) reflecting the main four geological formations were drawn.

Then, image representing multiple spectral slopes between bands 5,3 and 4 has been produced and by displaying this image with two classes defined by quanoles resulted in a separation between outcrop of sands and basements.

To draw out the boundary of alluvial deposits a linear spectral slop image has been calculated and displayed with 7 classes defined by quantiles and by visual interpretation the la£t class with the highest value of rat»o represented alluvial deposits nch with clay minerals.

For geological mapping of basalt outcrop bands ratios 6/7 6/2 and (4/5*6/5> were calculated and composited m R, 6, and B.

respectively.

By combining the layers obtained from the previous Stages, the geological map of the Study area was obtained, which is compatible with the eld geological maps and exceeds them with its high spatial accuracy, updating and the possibility of producing it us*ng very recent data whenever needed.