Water Quality Assessment in the Bamoun Plateau, Western-Cameroon: Hydrogeochemical Modelling and Multivariate Statistical Analysis Approach

This study focuses on the geochemical and bacteriological investigation of surface and ground water in the Bamoun plateau (Western-Cameroon). During the period from September 2013 to August 2014, 71 samples were collected from two springs, one borehole, four wells and the Nchi stream for analysis of major elements. In order to obtain the characteristics of the various species of bacteria, 7 samples were selected. The analytical method adopted for this study is the conventional hydrochemical technic and multivariate statistical analysis, coupled with the hydrogeochemical modelling. The results revealed that, water from the zone under study are acidic to basic, very weakly to weakly mineralized. Four types of water were identified: 1) CaMg-HCO3;2) CaMg-Cl-SO4;3) NaCl-SO4 and 4) NaK-HCO3. The major elements were all listed in the World Health Organization guidelines for drinking water quality, except for nitrates which was found at a concentration > 50 mg /l NO-3 in the borehole F401. As for the hydrobiological aspect, the entire sample contained all the bacteriological species except for spring S301 and well P401. According to the hydrogeochemical modelling, the Gibbs model and multivariate statistical tests, the quality of surface and ground water of the Foumban locality is influenced by two important factors: 1) the natural factors characterized by the water-rock interaction, evapotranspiration/crystallization, 2) the anthropogenic factors such as: uncontrolled discharges of liquid and solid effluents of all kinds and without any prior treatment within the ground and the strong urbanization accompanied by lack of sanitation and insufficient care.

Use of Landsat 8 OLI Images to Assess Groundwater Potential Areas in the Bamun Plateau: Cameroon Volcanic Line (CVL)

The problem of groundwater supply in the Bamun plateau situated in the Cameroon Volcanic Line exists and no proper solution has been found so far. This investigation intends to find the suitable groundwater potential zones by overlaying the geomorphologic map, lineament map, lineament density map and lithological map, using visual interpretation of Landsat imagery. The results reveal that about 1921 structural elements, ranging in size, from 30 m to 5.845 km with an average length of 671 m in the field. The total length of the mapped lineaments is approximately 1289 km. The most important lineament (5.845 km length) diagonally crosses the study area in the direction NNE-SSW. In addition to this trend, all others are smaller than 14 km. More than 92% of lineaments are less than 5 km in size and only 1.3% of them are larger than 10 km. Small lineaments are thus the most numerous. According to their directions, the lineaments listed are grouped into 18 directional classes of 10-degree intervals. The rosette of their directions highlights the preferred directions NE-SW, N-S, E-W, NNE-SSW and ENE-WSW. Most of the lineaments clusters in the central part of the area are N20° - 30°E and N60° - 70°E trending lineaments. In this study, the NE-SW trend dominates the structural trend followed by NW-SE and N-S. This can be an indication of the directions of groundwater movement in the area. Alluvial plain and valley have moderate to very good groundwater potential that occurs all over the study area. Porosity of the volcanic rocks varies greatly, but it is everywhere more porous than the underlying, unweathered bedrock. There are essentially three classes (low, average and high) of groundwater potential zones. Hight potential zones are observed around the localities of the Khogham, Mbatpit and Mbam massifs on the one hand and Manswen, Njikwop, Mfelap, Foumban, Njindaré, Nkoundem and Ngwen jigoumbé localities on the other hand. About 13% of the area has good groundwater potential around the mountains while 58% is moderately good which corresponds to high to moderate lineament densities situated at average altitude 1200 m and about 31% of the area has poor groundwater potential corresponding to low lineament density areas. Moreover, this work has helped develop a detailed lineament map that can be used for mining and hydrological prospecting campaigns.

Assessment of Surface Water Quality of Bétaré-Oya Gold Mining Area (East-Cameroon)

To assess the water quality in the locality of Bétaré-Oya affected by an intensive artisanal and semi mechanized mining activities, 71 samples were collected from sixteen points during the 2015-2016 hydrological year. These points include: three in Lom river which is the main stream of the study area, five in Mari river which is one of the left bank tributaries of the Lom, in Bétaré-Oya and eight in the left and the right bank of Mari. Different physicochemical parameters such as pH, electrical conductivity (EC), alkalinity, turbidity, total suspended solids (TSS), cyanide (CN-), major elements and heavy metals (Pb, Zn, Cd, Fe, Cu, As, Mn and Cr) were analyzed. Water Quality Indices (WQI), Heavy metal Pollution Index (HPI), sodium adsorption ratio (SAR) and percent sodium (Na%) were also computed to evaluate the suitability of water for drinking and irrigation. The results showed that the surface water from Bétaré-Oya was acidic to basic (5.40 < pH < 8.84), weakly mineralized (11.60 < EC < 122.10 μS/cm) with a high concentration of TSS (2 < TSS < 8996.00 mg/L) and turbidity (1.22 to 4758.00 NTU). The WQI scores show excellently to unsuitable quality in almost all the sampling sites. The water quality is found to be most deteriorated in Lom river and in the downstream of Mari river where an extensive mining activity is carried out, with the high WQI value of 5137.40. Based on heavy metal pollution index, the mean value was 1195.36 and thus under the critical pollution index. We thus notice a serious physical degradation by organic and mineral suspended particles as well as chemical degradation by heavy metals. This results from mining activities in the Lom river and its main tributaries such as the Mari river in the upstream part of the Sanaga basin. According to the percentage of sodium and SAR, these waters can be used for irrigation purposes in almost all types of soils.