标题：Morpho-Structural Mapping Constraints from Geophysical and Test Pit Investigations: Case Study of the Bomkoul Locality in Douala Sedimentary Basin, Cameroon, Central Africa
期刊名称：Journal of Geoscience and Environment Protection
印刷版ISSN：2327-4336
电子版ISSN：2327-4344
出版年度：2019
卷号：7
期号：10
页码：136-153
DOI：10.4236/gep.2019.710011
语种：English
出版社：Scientific Research Pub
摘要：A survey using the electrical resistivity and test pit methods is carried out in the Douala subbasin in order to investigate the sub-surface layering and evaluate the thickness of each layer through the variation of the resistivity with the depth. Applying the Schumberger array, a total of 48 vertical electrical sounding is conducted along 8 profiles directed W-E and using traditional method, 25 test pits with depth between 15 and 19 meters are done. Qualitative interpretation is carried out through the resistivity and test pit maps. The test pit maps reveal the presence of the following layers: The first layer of thickness varies from 0.2 to 2.0 m (average of 1.9 m). The thickness of the second layer varies between 0.2 and 4.0 m with an average of 2.8 m. The thickness of the third layer is between 2.0 and 4.0 m with an average of 3.8 m. That of the fourth and fifth layers ranges respectively between 4.0 and 6.0 m (average of 5.4 m) and between 2.0 and 6.0 m with an average of 4.4 m. Isoresistivities maps from resistivities computed for different AB/2 values (1.5; 4.4; 13.5; 19; 27.5; 58 m) are generally characterized by the apparent resistivities which define many domains in function of the AB/2 values. The superficial layer is characterized by electric resistivity values ranging from 720 to 2073 Ωm for AB/2 = 1.5 m and probably represents pedologic materials. For other values of AB/2, resistivity varies from 253 to 32,381 Ωm (AB/2 = 4.4 m), 0.1 to 1838 (AB/2 = 13.2 m) with an average of 341 Ωm, 0.3 to 1608 Ωm (AB/2 = 19 m) with an average of 279 Ωm, 6.4 to 1427 Ωm (AB/2 = 27.5 m) with an average 291 Ωm, and 19.7 to 3555 Ωm (AB/2 = 58 m) with an average of 850 Ωm. These different values of resistivity represent the sedimentary materials.
