Groundwater studies in parts of the Mamfe basin are sparse and the Mamfe area has the highest population density in the Mamfe basin. An in-depth study of groundwater rock interaction and groundwater quality is of vital importance. This same part of the basin is the economic centre and as such development of businesses in this area requires knowledge of the groundwater quality. Therefore , this study was undertaken to determine the input of the rock formations on the groundwater solute chemistry and groundwater domestic-agro-industrial quality using hydrogeochemical tools and physicochemical parameters : Ionic ratios, Gibbs diagrams, Piper diagrams, Durov diagrams and water quality indices. From physicochemical parameters , in the rainy season, pH ranged from, 4.3 - 8.6; EC, 3 - 1348 μS/cm; Temperature, 24.4 ℃ - 30.1 ℃ andTDS, 2.01 - 903.16 mg/L and in the dry season , pH ranged from 5.5 - 9.3; EC, 6 - 994 μS/cm; Temperature, 25 ℃ - 38.6℃ andTDS, 4.02 - 632.48 mg/L. Forty groundwater samples : 20 per season, wet and dry were analysed. The major ions fell below WHO acceptable limits for both seasons. The sequences of abundance of major ions were : Ca2+ > K+ > Mg2+ > > Na+, Cl- > > > > NO3 in wet season and Ca2+ > Mg2+ > K+ > Na+, > Cl- > > > in dry season. Ion-exchange, simple dissolution and uncommon dissolution processes determined groundwater character. Groundwater ionic content was as a result of ion exchange from rock-weathering. Water types are : CaSO4 and MgHCO3 in both seasons. Hydrogeochemical facies are Ca-Mg-Cl-SO4 and Ca-Mg-HCO3. SAR for wet season 0.05 - 0.06 and dry season 0.00 - 0.05, %Na wet season 3.64 - 16.59 and dry season 1.22 - 10.97, KR wet season 0.01 - 0.02 and 0.00
Water is an important natural resource essential for the existence of life and is basic human entity. Water resources are used for various purposes like drinking, agricultural, industrial, household, recreational, and environmental activities. Groundwater is one of the major sources of drinking water all over the world (Bear, 1979) . There has been tremendous increase in the demand for fresh water due to growth in population. Since groundwater is a renewable natural resource and a valuable component of the ecosystem, it is vulnerable to natural and human impacts. It is estimated that approximately one-third of the world’s population uses groundwater for drinking (Nickson et al., 2005) . In most parts of the Mamfe basin, groundwater is the major source of water supply for drinking and agricultural purposes. Few studies on groundwater quality have been carried out in this area, thus the groundwater might present a potential health hazard as such there was a need to determine the domestic-agro-industrial quality. Groundwater quality data give important clues to the geologic history, rock type and indications of groundwater recharge, discharge and storage (Walton, 1970) . Variations in groundwater quality in an area are a function of physical and chemical parameters that are greatly influenced by geological formations and anthropogenic properties (Kumar et al., 2011) . According to Babiker et al. (2007) , the chemistry of groundwater is not only related to the lithology of the area and the residence time the water is in contact with rock material, but also reflects inputs from the atmosphere, from soil and weathering as well as from pollutant sources such as mining, land clearance, saline intrusion, industrial and domestic wastes. Groundwater used for domestic and irrigation purposes can vary greatly in quality depending upon type and quantity of dissolved salts. It contains a wide variety of dissolved inorganic chemical constituents in various concentrations, resulting from chemical and biochemical interactions between water and the geological materials. Dissolved salts should be present in irrigation water in relatively small but significant amounts. They originate from dissolution or weathering of the rocks and soil, including dissolution of lime, gypsum and other slowly dissolved soil minerals. Research on groundwater studies in parts of the Mamfe basin is sparse and Mamfe area has the highest population density in the basin. An in-depth study of groundwater rock interaction and groundwater quality is of vital importance. This same part of the basin is the economic centre and as such development of business in the study area requires knowledge on groundwater quality. Therefore, the present study was carried out to determine the contribution of the formations to groundwater chemistry, groundwater quality and its suitability for drinking and agricultural uses in parts of the Mamfe basin.
Mamfe and environs is situate between latitude 5.65 - 5.85N and longitude 9.25 - 9.55E
The study area forms part of the Mamfe basin which lies along the Cameroon Volcanic Line. Sedimentation began in the Mamfe basin during the Albian (Dumort, 1968) and lithologies making-up the body of sediments are: basal conglomerates, conglomeratic sandstones, mudstones, shales, calcareous and carbonaceous rocks
the Benue trough and is linked with the West Central African Rift System (CWARS) thought to have formed during the Albian to Cenomanian (Eyong et al., 2013) as a result of basement rifting associated with the reactivation of E-W trending mylonite zones within the Pan-African basement (Dumort, 1968) . The basin narrows towards the east and widens towards the west across the Cameroon/Nigeria border into the Benue trough were Albianmarine deposits of Abakaliki Formation outcrops. The basin is fringed by reactivated, fault-bounded granite-gneissic rocks of the Pan-African Mobile Belt (550 ± 100 Ma) and are both intruded by volcanic rocks (Eyong et al., 2013) .
Mamfe Basin lies in a NW-SE trending trough with a length of 130 km and a width of 60 km and constitutes a small prolongation of the Benue trough (Nguimbous-Kouoh et al., 2012) . Ndougsa-Mbarga et al. (2007) described the Mamfe basin as the smallest of three side rifts associated with the Benue trough of west-central Africa. It extends from the lower Benue trough in Nigeria into Southwestern Cameroon where it narrows and terminates under the Cameroon volcanic line.
The Mamfe basin is bordered to the south by the Oban Massif granito-gneissic Precambrian Basement Complex which separates it from the Rio del Rey Basin and to the North by the Precambrian rocks of the Obudu Massif. To the West the Basin is open and continues as a part of Anambra basin of Nigeria and in the East and Northeast it narrows and terminates under the CVL.
The field materials and equipment used in the study are listed in
Equipment/Softwares | Specifications | Functions |
---|---|---|
Bike | Commercial bikes (Bensikin) | To transport fieldworkers to wells |
GPS | GARMIN GPSMAP 60CSx | To measure longitude, latitude and elevation of wells |
EC Meter | HANNA HI 98304/HI98303 | To measure Electrical Conductivity of water. |
pH Meter | HANNA HI 98127/HI98107 | To measure pH of water. |
Water level indicator | Solinst Model 102M | To indicate static water levels of water in wells |
Measuring Tape | Weighted measuring tape | Measurement of well diameter and depth. |
Digital Thermometer | Extech 39240 (−50˚C to 200˚C) | To measure temperature of water |
Total Dissolved Solid meter | Hanna HI 96301 with ATC | To measure Total dissolved solids in water |
Water sampler | Gallenkampf 1000 ml | To collect well water sample from well |
Sample bottles | Polystyrene 500 ml | To hold sample for onward transmission to laboratory |
ArcGIS | Version 10.1 | GIS Drawing sampling/Tests location maps |
Global Mapper | Version 15 | GIS Geolocation of wells |
Surfer Golden Software | Version 12 | GIS plotting contours for spatial distribution |
AqQA/Aquachem | Version 15 | For the analysis/interpretation of water chemistry |
A reconnaissance survey was carried out to identify wells, springs and streams in June 2016 as per ISO 5667-1 (2006) . Seasonal tests/measurements were carried out in September 2016 wet season and Dry season February 2017 respectively. 53 dug wells, were measured/tested in situ for: coordinates of wells, Surface elevation, Well water level, Dug wells depths well diameter, Electrical conductivity (EC), pH, Total dissolved solids (TDS) and Temperature (˚C). Forty (40) groundwater samples 20 in wet and dry seasons were collected in a high density polyethylene (HPDE) 500 ml bottles sealed and sent to the laboratory as per sampling protocols; ISO 5667-3 (2003) , ISO 5667-11 (2009) using the standard methods APHA (1995) to analyze for:
1) Major cations in mg/L: Ca2+, Mg2+, Na+, K+ and NH 4 + .
2) Major anions in mg/L: HCO 3 − , Cl−, SO 4 2 − , HPO 4 2 − and NO 3 −
Ionic ratio for indicative elements is a useful hydrogeochemical tool to identify source rock of ions and formation contribution to solute hydrogeochemistry Hounslow (1995) . These were used in this study.
Gibbs Diagram is a plot of Na+/(Na+ + HCO 3 − Ca2+) and Cl−/(Cl + HCO 3 − ) as a function of TDS are widely employed to determine the sources of dissolved geochemical constituents. These plots reveal the relationships between water composition and the three main hydrogeochemical processes involved in ions acquisition; Atmospheric precipitation, rock weathering or evaporation crystallisation.
Pipers Diagram is a graphical representation of the chemistry of water sample on three fields; the cation ternary field with Ca, Mg and Na + Kapices, the anion ternary field with HCO3, SO4 and Cl− apices. These two fields are projected onto a third diamond field. The diamond field is a matrix transformation of the graph of the anions [sulfate + chloride]/Ʃ anions and cations [Na + K]/Ʃ cations. This plot is a useful hydrogeochemical tool to compare water samples, determine water type and hydrogeochemical facies Langguth (1966) . This has been used here for these purposes.
Durov diagram is a composite plot consisting of two ternary diagrams where the milliequivalent percentages of cations are plotted perpendicularly against those of anions; the sides of the triangles form a central rectangular binary plot of total cation vs. total anion concentrations. These are divided into nine classes by Lloyd and Heathcoat (1985) which give the hydrogeochemical processes determining the character of the water types in the aquiferous formation Langguth (1966) .
WQI was calculated by adopting Weighted Arithmetical Index method considering thirteen water quality parameters (pH, EC, TDS, total alkalinity, total hardness, Ca2+, Mg2+, Na+, K+, Cl−, SO 4 2 − , NO 3 − , NH 4 + ) in order to assess the degree of groundwater contamination and suitability
For Agro-industrial suitability the following parameters were used; sodium adsorption ratio SAR, permeability index PI, Magnesium adsorption ratio MAR , percent sodium %Na, Kelly’s ratio KR and Residual sodium carbonate RSC and Wilcox diagram
The following sofwares; Surfer 12, Global mapper 11 and AqQA 1.5 AGIS 10.3 were used for data presentation, interpretation and analysis.
The physicochemical parameters groundwater in Mamfe: Temperature, pH, EC
Formula | Reference | |
---|---|---|
Percentage Sodium | % Na = Na + + K + Na + + K + + Ca 2 + + Mg 2 + × 100 | Wilcox (1955) |
Kelly Ratio | KR = Na + Ca 2 + + Mg 2 + | Kelley (1940) |
Magnesium Absorption Ratio | MAR = ( Mg 2 + Mg 2 + + Ca 2 + ) × 100 | Paliwal (1972) |
Total Hardness | TH (CaCO3) mg/L = 2.5 Ca2+ + 4.1 Mg2+ | Todd (1980) |
Residual Sodium Carbonate | RSC = ( CO 3 + HCO 3 − ( Ca + Mg ) ) | Eaton (1950) |
Sodium Absorption Ratio | SAR = Na Ca + Mg 2 | Richards (1954) |
Permeability Index | PI = ( ( Na + K ) + HCO 3 ) ∗ 100 Ca + Mg + Na + K | Doneen (1962) |
Water Quality Index | WQI = ∑ i = 1 n W i q i [ ∑ i = 1 n W i i ] − 1 | Sisodia and Moundiotiya (2006) |
and TDS for 53 wells were evaluated as shown in
Water Level Fluctuations
Depth-to statues water values (m) of groundwater in Mamfe ranged from: 0.5 - 9.5 in the Wet season and 0.5 - 14.5 in the dry season
Groundwater flow direction
Groundwater flows towards the Northwestern part of the study area during the wet season and dry season but during the dry season some water flows towards Bachuo-Akagbe
Temperature
Temperature values ˚C of Mamfe groundwater ranged from: 24.4 - 30.1 wet season 25˚C - 38.6˚C
pH
The pH value of most of the groundwater samples in the study area ranged from 4.3 - 8.6 in the wet season and 5.5 - 9.3 in the dry season
Parameters | Wet | Dry | ||||||
---|---|---|---|---|---|---|---|---|
Min | Max | Mean | Std. | Min | Max | Mean | Std. | |
T(˚C) | 24.4 | 30.1 | 27.77 | 0.98 | 25 | 38.6 | 28.04 | 2.46 |
PH | 4.3 | 8.6 | 6.11 | 0.87 | 5.5 | 9.3 | 7.53 | 0.75 |
EC (µS/cm) | 3 | 1348 | 178.9 | 202.5 | 6.0 | 944 | 174.89 | 162.03 |
TDS (mg/L) | 2 | 903.16 | 119.89 | 135.65 | 4.02 | 632.48 | 100.13 | 108.52 |
clearly shows that the groundwater in the study area is slightly acidic to alkaline in both seasons.
Electrical conductivity (EC)
The EC ranges from 3 - 1348 µS/cm during the wet season and 6 - 944 µS/cm during the dry season
The high electrical conductivity is due to high solute concentration in water.
Total dissolved solids (TDS)
The total dissolved solids range from 2.0 - 903.16 mg/L in the wet season and 4.02 - 632.48 mg/L in the dry season
The results of the chemical analysis varied in both seasons
Mechanism controlling water chemistry
Wet Season (mg/L) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
SN | Names | Na+ | K+ | Ca2+ | Mg2+ | NH 4 + | HPO 4 2 − | NO 3 − | SO 4 2 − | CL− | HPO 4 2 − |
1 | Bachuo-Akagbe 1 | 0.51 | 7.45 | 18.6 | 3.41 | 1.76 | 34.16 | 0.01 | 1.55 | 16.00 | 0 |
2 | Bachuo-Akagbe 2 | 0.09 | 0.86 | 5.40 | 3.22 | 1.71 | 3.66 | 0.00 | 1.46 | 36.00 | 0.06 |
3 | Bachuo-Akagbe 3 | 0.15 | 1.64 | 5.40 | 3.22 | 0.65 | 6.10 | 0.00 | 1.50 | 10.00 | 0.05 |
4 | Bachuo-Ntai 1 | 1.17 | 18.17 | 50.6 | 6.64 | 0.35 | 15.86 | 0.01 | 4.09 | 28.00 | 0.00 |
---|---|---|---|---|---|---|---|---|---|---|---|
5 | Bachuo-Ntai 2 | 0.06 | 0.51 | 2.66 | 3.41 | 0.94 | 4.88 | 0.00 | 1.74 | 0.00 | 0.00 |
6 | Bachuo-Ntai 3 | 0.41 | 6.2 | 15.98 | 4.39 | 1.91 | 0.00 | 0.00 | 1.97 | 8.00 | 0.36 |
7 | Okoyong 1 | 0.90 | 13.26 | 32 | 3.71 | 0.53 | 3.66 | 0.00 | 2.72 | 14.00 | 0.00 |
8 | Mile-1 | 0.69 | 7.41 | 21.4 | 3.61 | 3.06 | 0.00 | 0.00 | 3.38 | 26.00 | 0.00 |
9 | Garri quarter | 0.62 | 6.83 | 21.4 | 4.97 | 1.59 | 28.06 | 0.02 | 5.64 | 20.00 | 0.07 |
10 | Banya | 0.41 | 4.76 | 18.6 | 3.41 | 0.41 | 28.06 | 0.01 | 5.73 | 10.00 | 0.00 |
11 | New layout 1 | 0.62 | 6.83 | 21.4 | 4.19 | 0.82 | 10.98 | 0.01 | 2.44 | 36.00 | 0.02 |
12 | New layout 2 | 0.62 | 6.83 | 21.4 | 4.28 | 0.24 | 14.64 | 0.01 | 3.71 | 32.00 | 0.00 |
13 | Small Mamfe | 0.3 | 3.32 | 8.00 | 3.41 | 0.71 | 4.88 | 0.00 | 2.54 | 6.00 | 0.04 |
14 | Tanjong Street | 0.97 | 13.49 | 34.6 | 3.22 | 0.00 | 7.32 | 0.00 | 6.72 | 18.00 | 0.00 |
15 | Lalla | 0.14 | 1.01 | 8.00 | 3.31 | 0.12 | 0.00 | 0.00 | 1.93 | 10.00 | 0.06 |
16 | Egbekaw 1 | 0.51 | 5.69 | 18.6 | 5.08 | 0.24 | 37.82 | 0.01 | 7.99 | 14.00 | 0.00 |
17 | Egbekaw 2 | 2.23 | 29.52 | 82.6 | 9.36 | 0.71 | 18.3 | 0.01 | 3.76 | 96.00 | 0.00 |
18 | Spring | 0.18 | 1.13 | 8.00 | 3.31 | 0.35 | 10.98 | 0.01 | 2.44 | 0.00 | 0.00 |
19 | River Badi | 0.14 | 1.13 | 5.32 | 3.52 | 0.11 | 8.54 | 0.00 | 2.82 | 0.00 | 0.00 |
20 | Rain water | 0.28 | 2.61 | 10.66 | 2.93 | 0.00 | 2.44 | 0.00 | 1.60 | 4.00 | 0.00 |
Min | 0.06 | 0.51 | 2.66 | 2.93 | 0.00 | 0.00 | 0.00 | 1.46 | 0.00 | 0.00 | |
Max | 2.23 | 29.52 | 82.60 | 9.36 | 3.06 | 37.82 | 0.02 | 7.99 | 96.00 | 0.36 | |
Mean | 0.55 | 6.93 | 20.53 | 4.13 | 0.81 | 12.02 | 0.01 | 3.29 | 19.20 | 0.03 | |
Std. | 0.50 | 7.13 | 18.78 | 1.51 | 0.80 | 11.63 | 0.01 | 1.88 | 21.41 | 0.08 |
Dry Season (mg/L) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
SN | Names | Na+ | K+ | Ca2+ | Mg2+ | NH 4 + | HPO 4 2 − | NO 3 − | SO 4 2 − | CL− | HPO 4 2 − |
1 | Bachuo-Akagbe 1 | 0.64 | 9.34 | 21.45 | 20.14 | 0.00 | 45.24 | 0.00 | 0.15 | 12.00 | 0.00 |
2 | Bachuo-Akagbe 2 | 0.28 | 1.45 | 20.2 | 18.75 | 0.00 | 91.18 | 0.00 | 0.18 | 17.00 | 0.04 |
3 | Bachuo-Akagbe 3 | 0.94 | 2.38 | 20.15 | 18.94 | 0.00 | 90.25 | 0.00 | 0.14 | 10.00 | 0.02 |
4 | Bachuo-Ntai 1 | 0.13 | 16.23 | 60.14 | 21.1 | 0.00 | 121.05 | 0.00 | 1.42 | 15.00 | 0.00 |
5 | Bachuo-Ntai 2 | 0.18 | 1.88 | 21.25 | 20.01 | 0.00 | 51.25 | 0.00 | 0.14 | 0.00 | 0.00 |
6 | Bachuo-Ntai 3 | 0.64 | 6.95 | 16.75 | 15.95 | 0.00 | 150.00 | 0.00 | 0.11 | 0.00 | 0.25 |
7 | Okoyong 1 | 0.95 | 10.45 | 41.34 | 18.25 | 0.00 | 48.00 | 0.00 | 0.18 | 10.00 | 0.00 |
8 | Mile-1 | 0.88 | 8.95 | 28.05 | 20.25 | 0.00 | 120.00 | 0.00 | 1.12 | 16.00 | 0.00 |
9 | Garri quarter | 0.85 | 8.81 | 27.45 | 20.34 | 0.00 | 45.00 | 0.01 | 2.24 | 10.00 | 0.04 |
10 | Banya | 0.71 | 6.84 | 28.11 | 18.25 | 0.00 | 46.00 | 0.01 | 2.16 | 18.00 | 0.00 |
11 | New layout 1 | 0.84 | 8.74 | 25.00 | 19.74 | 0.00 | 37.00 | 0.01 | 0.19 | 0.00 | 0.01 |
12 | New layout 2 | 0.83 | 8.46 | 25.00 | 19.63 | 0.00 | 46.00 | 0.01 | 0.21 | 12.00 | 0.00 |
13 | Small Mamfe | 0.45 | 2.94 | 17.00 | 20.41 | 0.00 | 23.95 | 0.00 | 1.18 | 10.00 | 0.01 |
14 | Tanjong Street | 0.99 | 11.88 | 37.45 | 20.22 | 0.00 | 24.00 | 0.00 | 3.05 | 12.00 | 0.00 |
---|---|---|---|---|---|---|---|---|---|---|---|
15 | Lalla | 0.35 | 2.05 | 80.21 | 18.18 | 0.00 | 91.00 | 0.00 | 0.13 | 94.00 | 0.04 |
16 | Egbekaw 1 | 0.63 | 7.15 | 16.00 | 14.25 | 0.00 | 101.33 | 0.00 | 4.17 | 0.00 | 0.00 |
17 | Egbekaw 2 | 2.64 | 28.11 | 85.45 | 30.45 | 0.00 | 100.00 | 0.00 | 1.22 | 0.00 | 0.00 |
18 | Spring | 0.49 | 2.03 | 16.49 | 22.00 | 0.00 | 132.00 | 0.00 | 0.19 | 0.00 | 0.00 |
19 | River Badi | 0.37 | 2.05 | 12.94 | 20.00 | 0.00 | 130.00 | 0.00 | 0.18 | 0.00 | 0.00 |
20 | Rain water | 0.57 | 4.90 | 8.00 | 16.26 | 0.00 | 19.79 | 0.02 | 0.16 | 0.00 | 0.02 |
Min | 0.13 | 1.45 | 8.00 | 14.25 | 0.00 | 19.79 | 0.00 | 0.11 | 0.00 | 0.00 | |
Max | 2.64 | 28.11 | 85.45 | 30.45 | 0.00 | 150.00 | 0.02 | 4.17 | 94.00 | 0.25 | |
Mean | 0.72 | 7.58 | 30.42 | 19.66 | 0.00 | 75.65 | 0.00 | 0.93 | 11.80 | 0.02 | |
Std. | 0.52 | 6.29 | 21.26 | 3.15 | 0.00 | 41.40 | 0.01 | 1.16 | 20.49 | 0.06 |
Ionic ratios of groundwater in Mamfe
18 ionic ratios in groundwater were used to deduce formation inputs in parts of the Mamfe basin, as follows Tables 5(a)-(c).
SN | SO4 /Cl | Na /Cl | Mg /Cl | Na /HCO3 | Ca /HCO3 | Ca /SO4 | Ca /Mg | Ca + Mg/ Na + K | HCO3/ ∑An | NO3/ ∑An | SO4/ ∑An | Mg /Ca | Na /Na + Cl | Mg/ Ca + Mg | Ca /Ca + SO4) | Ca + Mg SO4 | Cl /∑An | Na + K-Cl /Na + K + Cl-Ca |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 0.10 | 0.03 | 0.21 | 0.01 | 0.54 | 12.00 | 0.00 | 0.00 | 0.05 | 0.00 | 0.00 | 0.18 | 0.03 | 0.15 | 0.92 | 14.20 | 0.02 | 0.30 |
2 | 0.04 | 0.00 | 0.09 | 0.02 | 1.48 | 3.70 | 1.68 | 9.07 | 0.01 | 0.00 | 0.00 | 0.60 | 0.00 | 0.37 | 0.79 | 5.90 | 0.05 | 0.87 |
3 | 0.15 | 0.02 | 0.32 | 0.02 | 0.89 | 3.60 | 1.68 | 4.82 | 0.01 | 0.00 | 0.00 | 0.60 | 0.01 | 0.37 | 0.78 | 5.75 | 0.01 | 0.60 |
4 | 0.15 | 0.04 | 0.24 | 0.07 | 3.19 | 12.37 | 7.62 | 2.96 | 0.02 | 0.00 | 0.01 | 0.13 | 0.04 | 0.12 | 0.93 | 14.00 | 0.04 | 0.15 |
5 | 0.00 | 0.00 | 0.00 | 0.01 | 0.55 | 1.53 | 0.78 | 10.65 | 0.01 | 0.00 | 0.00 | 1.28 | 1.00 | 0.56 | 0.60 | 3.49 | 0.00 | −0.27 |
6 | 0.25 | 0.05 | 0.55 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.27 | 0.05 | 0.22 | 0.89 | 10.34 | 0.01 | 0.08 |
7 | 0.19 | 0.06 | 0.27 | 0.25 | 8.74 | 0.00 | 8.63 | 2.52 | 0.01 | 0.00 | 0.00 | 0.12 | 0.06 | 0.10 | 0.92 | 13.13 | 0.02 | −0.01 |
8 | 0.13 | 0.03 | 0.14 | 0.00 | 0.00 | 6.33 | 0.00 | 3.09 | 0.00 | 0.00 | 0.00 | 0.17 | 0.03 | 0.14 | 0.86 | 7.40 | 0.04 | 0.46 |
9 | 0.28 | 0.03 | 0.25 | 0.02 | 0.76 | 3.79 | 4.31 | 3.54 | 0.04 | 0.00 | 0.01 | 0.23 | 0.03 | 0.19 | 0.79 | 4.68 | 0.03 | 0.37 |
10 | 0.57 | 0.04 | 0.34 | 0.01 | 0.66 | 3.25 | 0.00 | 0.00 | 0.04 | 0.00 | 0.01 | 0.18 | 0.04 | 0.15 | 0.76 | 3.84 | 0.01 | 0.21 |
11 | 0.07 | 0.02 | 0.12 | 0.06 | 1.95 | 0.00 | 5.11 | 3.43 | 0.02 | 0.00 | 0.00 | 0.20 | 0.02 | 0.16 | 0.90 | 10.49 | 0.05 | 0.57 |
12 | 0.12 | 0.02 | 0.13 | 0.04 | 1.46 | 0.00 | 5.00 | 3.45 | 0.02 | 0.00 | 0.01 | 0.20 | 0.02 | 0.17 | 0.85 | 6.92 | 0.05 | 0.53 |
13 | 0.42 | 0.05 | 0.57 | 0.06 | 1.64 | 3.15 | 2.35 | 0.00 | 0.01 | 0.00 | 0.00 | 0.43 | 0.05 | 0.30 | 0.76 | 4.49 | 0.01 | 0.23 |
14 | 0.37 | 0.05 | 0.18 | 0.13 | 4.73 | 0.00 | 10.75 | 0.00 | 0.01 | 0.00 | 0.01 | 0.09 | 0.05 | 0.09 | 0.84 | 5.63 | 0.03 | 0.09 |
15 | 0.19 | 0.01 | 0.33 | 0.00 | 0.00 | 4.15 | 2.42 | 9.83 | 0.00 | 0.00 | 0.00 | 0.41 | 0.01 | 0.29 | 0.81 | 5.86 | 0.01 | 0.53 |
16 | 0.57 | 0.04 | 0.36 | 0.01 | 0.49 | 2.33 | 3.66 | 3.82 | 0.05 | 0.00 | 0.01 | 0.27 | 0.04 | 0.21 | 0.70 | 2.96 | 0.02 | 0.30 |
17 | 0.04 | 0.02 | 0.10 | 0.00 | 0.00 | 0.00 | 8.82 | 0.00 | 0.03 | 0.00 | 0.01 | 0.11 | 0.02 | 0.10 | 0.96 | 24.46 | 0.14 | 0.44 |
18 | 0.00 | 0.00 | 0.00 | 0.02 | 0.73 | 3.28 | 2.42 | 8.63 | 0.02 | 0.00 | 0.00 | 0.41 | 1.00 | 0.29 | 0.77 | 4.64 | 0.00 | −0.20 |
19 | 0.00 | 0.00 | 0.00 | 0.02 | 0.62 | 1.89 | 1.51 | 6.96 | 0.01 | 0.00 | 0.00 | 0.66 | 1.00 | 0.40 | 0.65 | 3.13 | 0.00 | −0.31 |
20 | 0.40 | 0.07 | 0.73 | 0.11 | 4.37 | 6.66 | 3.64 | 4.70 | 0.00 | 0.00 | 0.00 | 0.27 | 0.07 | 0.22 | 0.87 | 8.49 | 0.01 | 0.09 |
Min | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.09 | 0.00 | 0.09 | 0.60 | 2.96 | 0.00 | −0.31 |
Max | 0.57 | 0.07 | 0.73 | 0.25 | 8.74 | 12.37 | 10.75 | 10.65 | 0.05 | 0.00 | 0.01 | 1.28 | 1.00 | 0.56 | 0.96 | 24.46 | 0.14 | 0.87 |
Mean | 0.20 | 0.03 | 0.25 | 0.04 | 1.64 | 3.40 | 3.52 | 3.87 | 0.02 | 0.00 | 0.00 | 0.34 | 0.18 | 0.23 | 0.82 | 7.99 | 0.03 | 0.25 |
Std. | 0.18 | 0.02 | 0.20 | 0.06 | 2.16 | 3.63 | 3.25 | 3.52 | 0.02 | 0.00 | 0.00 | 0.28 | 0.35 | 0.12 | 0.09 | 5.26 | 0.03 | 0.31 |
SN | SO4 /Cl | Na /Cl | Mg /Cl | Na /HCO3 | Ca /HCO3 | Ca /SO4 | Ca /Mg | Ca + Mg/ Na + K | HCO3/ ∑An | NO3/ ∑An | SO4/ ∑An | Mg /Ca | Na /Na + Cl | Mg /Ca + Mg | Ca /Ca + SO4 | Ca + Mg /SO4 | Cl /∑An | Na + K-Cl /Na + k + Cl-Ca |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 0.01 | 0.05 | 1.68 | 0.01 | 0.47 | 143.00 | 0.00 | 0.00 | 0.03 | 0.00 | 0.00 | 1.68 | 0.05 | 0.48 | 0.99 | 277.27 | 0.01 | 0.09 |
2 | 0.01 | 0.02 | 1.10 | 0.00 | 0.22 | 112.22 | 1.08 | 22.51 | 0.05 | 0.00 | 0.00 | 1.10 | 0.02 | 0.48 | 0.99 | 216.39 | 0.01 | 0.43 |
3 | 0.01 | 0.09 | 1.89 | 0.01 | 0.22 | 143.93 | 1.06 | 11.77 | 0.05 | 0.00 | 0.00 | 1.89 | 0.09 | 0.48 | 0.99 | 279.21 | 0.01 | 0.25 |
4 | 0.09 | 0.01 | 1.41 | 0.00 | 0.50 | 42.35 | 2.85 | 4.97 | 0.07 | 0.00 | 0.00 | 1.41 | 0.01 | 0.26 | 0.98 | 57.21 | 0.01 | −0.02 |
5 | 0.00 | 0.00 | 0.00 | 0.00 | 0.41 | 151.79 | 1.06 | 20.03 | 0.03 | 0.00 | 0.00 | 0.00 | 1.00 | 0.48 | 0.99 | 294.71 | 0.00 | −0.11 |
6 | 0.00 | 0.00 | 0.00 | 0.00 | 0.11 | 0.00 | 0.00 | 0.00 | 0.08 | 0.00 | 0.00 | 0.00 | 1.00 | 0.49 | 0.99 | 297.27 | 0.00 | −0.83 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
7 | 0.02 | 0.10 | 1.83 | 0.02 | 0.86 | 0.00 | 2.27 | 5.23 | 0.03 | 0.00 | 0.00 | 1.83 | 0.09 | 0.31 | 1.00 | 331.06 | 0.01 | −0.04 |
8 | 0.07 | 0.06 | 1.27 | 0.01 | 0.23 | 25.04 | 0.00 | 4.91 | 0.07 | 0.00 | 0.00 | 1.27 | 0.05 | 0.42 | 0.96 | 43.13 | 0.01 | 0.18 |
9 | 0.22 | 0.09 | 2.03 | 0.02 | 0.61 | 12.25 | 1.35 | 4.95 | 0.03 | 0.00 | 0.00 | 2.03 | 0.08 | 0.43 | 0.92 | 21.33 | 0.01 | 0.01 |
10 | 0.12 | 0.04 | 1.01 | 0.02 | 0.61 | 13.01 | 0.00 | 0.00 | 0.03 | 0.00 | 0.00 | 1.01 | 0.04 | 0.39 | 0.93 | 21.46 | 0.01 | 0.27 |
11 | 0.00 | 0.00 | 0.00 | 0.02 | 0.68 | 0.00 | 1.27 | 4.67 | 0.02 | 0.00 | 0.00 | 0.00 | 1.00 | 0.44 | 0.99 | 235.47 | 0.00 | −0.62 |
12 | 0.02 | 0.07 | 1.64 | 0.02 | 0.54 | 0.00 | 1.27 | 4.80 | 0.03 | 0.00 | 0.00 | 1.64 | 0.06 | 0.44 | 0.99 | 212.52 | 0.01 | 0.10 |
13 | 0.12 | 0.05 | 2.04 | 0.02 | 0.71 | 14.41 | 0.83 | 0.00 | 0.01 | 0.00 | 0.00 | 2.04 | 0.04 | 0.55 | 0.94 | 31.70 | 0.01 | 0.28 |
14 | 0.25 | 0.08 | 1.69 | 0.04 | 1.56 | 0.00 | 1.85 | 0.00 | 0.01 | 0.00 | 0.00 | 1.69 | 0.08 | 0.35 | 0.92 | 18.91 | 0.01 | −0.02 |
15 | 0.00 | 0.00 | 0.19 | 0.00 | 0.88 | 617.00 | 4.41 | 41.00 | 0.05 | 0.00 | 0.00 | 0.19 | 0.00 | 0.18 | 1.00 | 756.85 | 0.05 | 0.53 |
16 | 0.00 | 0.00 | 0.00 | 0.01 | 0.16 | 3.84 | 1.12 | 3.89 | 0.06 | 0.00 | 0.00 | 0.00 | 1.00 | 0.47 | 0.79 | 7.25 | 0.00 | −0.95 |
17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 2.81 | 0.00 | 0.06 | 0.00 | 0.00 | 0.00 | 1.00 | 0.26 | 0.99 | 95.00 | 0.00 | −0.56 |
18 | 0.00 | 0.00 | 0.00 | 0.00 | 0.12 | 86.79 | 0.75 | 15.27 | 0.07 | 0.00 | 0.00 | 0.00 | 1.00 | 0.57 | 0.99 | 202.58 | 0.00 | −0.18 |
19 | 0.00 | 0.00 | 0.00 | 0.00 | 0.10 | 71.89 | 0.65 | 13.61 | 0.07 | 0.00 | 0.00 | 0.00 | 1.00 | 0.61 | 0.99 | 183.00 | 0.00 | −0.23 |
20 | 0.00 | 0.00 | 0.00 | 0.03 | 0.40 | 50.00 | 0.49 | 4.44 | 0.01 | 0.00 | 0.00 | 0.00 | 1.00 | 0.67 | 0.98 | 151.63 | 0.00 | −2.16 |
Min | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.01 | 0.00 | 0.00 | 0.00 | 0.00 | 0.18 | 0.79 | 7.25 | 0.00 | −2.16 |
Max | 0.25 | 0.10 | 2.04 | 0.04 | 1.56 | 617.00 | 4.41 | 41.00 | 0.08 | 0.00 | 0.00 | 2.04 | 1.00 | 0.67 | 1.00 | 756.85 | 0.05 | 0.53 |
Mean | 0.05 | 0.03 | 0.89 | 0.01 | 0.47 | 74.38 | 1.26 | 8.10 | 0.04 | 0.00 | 0.00 | 0.89 | 0.43 | 0.44 | 0.97 | 186.70 | 0.01 | −0.18 |
Std. | 0.08 | 0.04 | 0.85 | 0.01 | 0.37 | 138.60 | 1.13 | 10.29 | 0.02 | 0.00 | 0.00 | 0.85 | 0.48 | 0.12 | 0.05 | 174.24 | 0.01 | 0.61 |
Ionic ratio | Wet | Dry | Comment | Interpretation |
---|---|---|---|---|
SO4/Cl | 0.00 - 0.57 | 0 - 0.25 | high | Additional sources of SO4 from weathering of sulfates |
Na/Cl | 0.00 - 0.07 | 0 - 0.01 | low | No Na-adsorption during freshening and a little silicate weathering |
Mg/Cl | 0.00 to 0.73 | 0 - 2.04 | high | Cation-exchange and silicate weathering of sandstones. |
Na/HCO3 | 0.01 - 0.25 | 0 - 0.004 | high | Substantial weathering of Na-feldspar or other Na-silicates |
Ca/HCO3 | 0.00 - 8.74 | 0 - 1.56 | high | Calc-carbonate dissolution or Calc-silicate weathering |
Ca/SO4 | 1.53 - 21.97 | 3.84 - 617 | high | Gypsum dissolution present |
Ca/Mg | 0.00 - 10.75 | 0 - 4.41 | high | Cation-exchange of weathering of silicate rocks. |
Ca + Mg/Na + K | 0.00 - 10.65 | 0.00 - 41.00 | high | Carbonate weathering |
HCO3/∑Anions | 0.00 - 0.05 | 0.01 - 0.08 | high | Weathering reactions and input of dissolved species in recharge area |
NO3/∑Anions | 0.00 - 2.8E−6 | 0.00 - 5.6E−6 | very low | No anthropogenic contribution |
SO4/∑Anions | 0.00 - 0.01 | 0.00 - 2.3E−3 | very low | No oxidation of sulphides. |
Mg/Ca | 0.09 - 1.28 | 0.00 - 2.04 | low | Weathering of Silicate rocks |
Na/Na + Cl | 0.00 - 1.00 | 0.00 - 1.00 | high | Sodium source other than halite-albite, ion exchange |
Mg/Ca + Mg | 0.09 - 0.56 | 0.18 - 0.67 | high | Dolomite dissolution, calcite precipitation or saltwater |
Ca /Ca + SO4 | 0.60 - 0.96 | 0.79 - 1.00 | high | Calcium source other than gypsum |
Ca + Mg/SO4 | 2.96 - 24.46 | 7.25 - 756.85 | ||
Na + K-Cl/Na + K-Cl + Ca | −0.31 - 0.87 | −2.16 - 0.53 | high | Plagioclase weathering unlikely |
Cl/∑Anions | 0.00 - 0.14 | 0.00 - 0.05 | low | Rock weathering |
12 of the 18 66.7% ionic ratios calculated gave indices indicating weathering of geologic formations in the Mamfe basin as a source of solute concentration in the groundwater while nitrate ratio indicates no anthropogenic contribution and sulfate indices indicates no oxidation of sulfides. Ca is sourced from gypsum while Na is sourced from halite-albite and ion exchange. Mg is contributed by dolomite dissolution, calcite precipitation or saltwater. There is no plagioclase weathering. These high indices values are found in the following localities Lalla, Okoyong, Bachuo-Ntai, Bachuo-Akagbe and Egbekaw.
Gibbs diagrams of groundwater in Mamfe
The Gibbs diagrams were used. In the wet season 17 samples 85% plot in the rock-weathering dominance field and 3 samples 85% plot in the atmospheric precipitation dominance field. In the dry season 16 samples 80% plot in the rock-weathering dominance field and 4 samples 20% plot in atmospheric dominance field
Type | Range | Wet | Dry | ||||||
---|---|---|---|---|---|---|---|---|---|
Cation | % | Anion | % | Cation | % | Anion | % | ||
Rock - Weathering dominance | 50 - 1000 | 17 | 85 | 17 | 85 | 16 | 80 | 16 | 80 |
Atmospheric Precipitation dominance | 1 - 50 | 3 | 15 | 3 | 15 | 4 | 10 | 4 | 20 |
Groundwater types
The diamond field of piper diagram after Piper (1944) has further been divided into seven fields classifying water types and designated with alphabets from A to G, Langguth (1966) . Using this classification, the water from the study area is distinguished into the A, B, and C categories. The D, E, F, and G water types are absent. In the rainy season; Category A, 3 samples 15%; characterized by normal earth alkaline water with prevailing bicarbonate. Category B, 3 samples 15% are characterized by normal earth alkaline water with prevailing sulfate or chloride and Category C, 14 samples 70%
Piper’s Hydrogeochemical facies
From the Piper’s diagrams, field I: Ca-Mg-Cl−-SO4 hydrogeochemical facies has 15 samples 75% in the rainy and 2 samples 10% in the dry season demonstrating the dominance of alkaline earths over alkali Ca + Mg > Na + K and strong acidic anions over weak acidic anions. Field IV, Ca-Mg-HCO3 hydrogeochemical facies has 5 samples 25% in the rainy and 18 samples 90% in the dry season
No samples plotted on field II and field III. The dominance of Ca-Mg-HCO3 hydrogeochemical facies in this area could be due to dissolution of gases and minerals, particularly CO2 and CO2-related compounds from the atmosphere
Wet | Dry | ||||
---|---|---|---|---|---|
Class | Description of Water Types | No | % | No | % |
A | Normal earth alkaline water with prevailing bicarbonate | 3 | 15 | 14 | 70 |
B | Normal earth alkaline water with prevailing bicarbonate and sulfate or chloride | 3 | 15 | 5 | 25 |
C | Normal earth alkaline water with prevailing Sulfate or Chloride | 14 | 70 | 1 | 5 |
Cations field | |||||
1 | Calcium rich | 18 | 90 | 6 | 30 |
2 | Magnesium rich | 2 | 10 | 14 | 70 |
Anion Field | |||||
4 | Bicarbonate rich | 6 | 30 | 19 | 95 |
5 | Chloride rich | 14 | 70 | 1 | 5 |
Field | Hydrogeochemical facies | Wet | % | Dry | % |
---|---|---|---|---|---|
Field I | Ca-Mg-Cl-SO4 | 15 | 75 | 2 | 10 |
Field IV | Ca-Mg-HCO3 | 5 | 25 | 18 | 90 |
dissolved in precipitation and during groundwater infiltration through the vadose zone.
Durov diagram
Based on the classification of Lloyd and Heathcoat (1985) : Six classes of processes occur in the rainy season; Class 1 recharging waters: 10 samples 50%; Class 2 ion exchange water: 5 samples 15%; Class 3 ion exchange water: 1 samples 5%; Class 5 simple dissolution or mixing: 1 samples 5%; Class 6 probable mixing or uncommon dissolution influences: 1 sample respectively 5% and Class 7 2 samples respectively 10%; Cl and Na dominant is frequently encountered, Otherwise the water may result from reverse ion exchange of Na-Cl waters
Wet | Dry | ||||
---|---|---|---|---|---|
SN | Description of Water Types | No | % | No | % |
1 | HCO3 and Ca dominant, frequently indicates recharging waters in limestone, sandstone, and many other aquifers | 10 | 50 | 0 | 0 |
2 | This water type is dominated by Ca and HCO3 ions. Association with dolomite is presumed if Mg is significant. However, those samples in which Na is significant, an important ion exchanged is presumed | 5 | 25 | 1 | 5 |
3 | HCO3 and Na are dominant, normally indicates ion exchanged water, although the generation of CO2 at depth can produce HCO3 where Na is dominant under certain circumstances | 1 | 5 | 3 | 15 |
5 | No dominant anion or cation, indicates water exhibiting simple dissolution or mixing | 1 | 5 | 5 | 25 |
6 | SO4 dominant or anion discriminate and Na dominant; is water type that is not frequently encountered and indicates probable mixing or uncommon dissolution influences. | 1 | 5 | 11 | 55 |
7 | Cl and Na dominant are frequently encountered or the water may have resulted from reverse ion exchange of Na-Cl waters | 2 | 10 | 0 | 0 |
Domestic Water Quality
Ionic content of water in the study area was used to evaluate groundwater suitability for domestic use: The recommended values are of the WHO (2017) guidelines. The quality standards for drinking water have been specified by the World Health Organization (WHO) 2017 . The suitability of groundwater in the study area based on WQI and total hardness HT are discussed below.
Water quality index (WQI)
The WHO (2017) permissible values of ions present in the groundwater have been used to calculate WQI values, Asadi et al. (2007) . Water Quality Index WQI considered the most effective tool to convey the water quality information in the simplest form to the public (Babaei, 2011). The WQI values range from 0 - 70.79 in the wet season and 13.2 - 276.6 in the dry. 80% of the water samples in the wet season can be considered suitable for domestic and other utilitarian purposes as they belong to excellent to good water quality classes
Total hardness (TH)
The total hardness of groundwater samples range from 20.63 - 244.87 mg/L in the wet season and 86.66 - 338.47 mg/L in the dry season
Index | Quality | WQI-wet | % | WQI-dry | % |
---|---|---|---|---|---|
0 - 25 | Excellent | 10 | 50 | 1 | 5 |
26 - 50 | Good | 6 | 30 | 3 | 15 |
51 - 75 | Poor | 4 | 20 | 2 | 10 |
76 - 100 | Very poor | 0 | 0 | 0 | 0 |
>100 | Unsuitable | 0 | 0 | 14 | 70 |
Wet | Dry | ||||
---|---|---|---|---|---|
Hardness (mg/L) | Classification | No | % | No | % |
0 - 75 | Soft | 16 | 80 | 0 | 0 |
76 - 150 | Moderately Hard | 2 | 10 | 13 | 65 |
151 - 300 | Hard | 2 | 10 | 6 | 30 |
>300 | Very Hard | 0 | 0 | 1 | 5 |
The important parameters which determine the irrigation water quality of the study area are discussed below;
Sodium percent
Sodium percent values range from 3.64 - 16.59 in wet season and 1.22 - 10.97 dry season. Sodium along with carbonate forms alkaline soil; while sodium with chloride forms saline soil; both of these are not suitable for the growth of plants (Pandian & Shankar 2007) . The quality classifications of irrigation water based on the values of sodium percentage as proposed by Wilcox (1955) suggest that the groundwater of the study area is good to permissible category both in the wet and dry season
Sodium adsorption ratio
SAR values range from 0.005 - 0.075 in rainy season and 0.01 - 0.14 during dry season. Based on the SAR values, all samples have low sodium hazard and on plotting over the USSL Salinity diagram (USSL 1954)
Hazard Class | EC (µS/cm) | Quality | Wet No % | Dry No % | ||
---|---|---|---|---|---|---|
C0 | 0 - 100 | Excellent | 4 | 20 | 6 | 30 |
C1 | 101 - 250 | Very Good | 13 | 65 | 8 | 40 |
C2 | 251 - 750 | Good | 3 | 15 | 6 | 30 |
Permeability index
The PI values range 0.89 - 68.63 in the wet season and 18.75 - 73.35 in the dry season
Magnesium Adsorption Ratio
Magnesium Ratio adsorption values range from 13.3 - 67.88 in the wet season and 27.02 - 77.01 in the dry season
Residual Sodium Carbonate
The RSC values −4.59 to −0.33 in the wet season and −5.13 - 0.3 mg/L in the dry season
Kelly’s Ratio (KR)
KR < 1 is considered suitable for irrigation and KR > 1 is unsuitable. During rainy season, KR values vary between 0.01 - 0.02 and during the dry season the values vary between 0.00 - 0.02
Temperature, pH, EC and TDS vary with seasons as such the groundwater is in hydraulic connectivity with the atmosphere indicative of a phreatic aquifer. All major ions fell below WHO (2017) acceptable limits for both seasons. From ionic ratios there are additional sources of SO4, silicate weathering possibly of the sandstones, conglomerates and other rocks in this area. Weathering of Na-feldspar or other Na-silicates and Ca-carbonate dissolution or Ca-silicate weathering. Cation-exchange of the silicate rocks with the groundwater. Ironic ratio values for nitrate and sulfate are very low as such there are no anthropogenic contribution and no oxidation of sulphides. Solutes from weathering reactions and inputs of dissolved species in precipitation get into the aquifer indicating a recharge zone. From Gibbs diagram there is the dominance of rock-weathering and atmospheric precipitation dominance. From Durov diagrams the processes involve are ion exchange, dissolution and mixing. From the Piper’s diagrams, the dominant hydrogeochemical facies are Ca-Mg-Cl-SO4 and Ca-Mg-HCO3 for both seasons. This facies is characteristic of freshly recharged groundwater that has equilibrated with CO2 and soluble carbonate minerals under an open system conditions in the vadose zone typical of shallow groundwater flow systems in crystalline phreatic aquifers.
From the above groundwater synthesis, WQI values indicate that 80% of the groundwater in the wet season can be considered suitable for domestic use, 20% are classified to be unfit for consumption whereas in the dry season 20% are suitable for domestic purposes and 80% are unfit for consumption as they belong to poor, very poor and unsuitable classes. Therefore the water in Mamfe is more suitable for domestic purposes in the wet season than in the dry season similar to work done in Kumba, by Akoachere et al. (2018) .
The values of SAR, PI, %Na, KR and WQI, RSC and Wilcox diagram indicate that most groundwater in the study area are suitable for irrigation purposes but of MAR with values higher in Mile-1, Kumba road, Egbekaw, and Bachuo-Ntai rendering the water unfit for irrigation.
Since there exist little hydrogeological or hydrological work in this part of the basin, there is little to compare the results here-in, this being the first study that sheds light into these unexplored aspects of the basin.
The geogenic input to groundwater is the weathering of rocks possibly of the granites, gneisses, sandstones, conglomerates, shales and other rocks in this area.
Groundwater ionic content was as a result of ion exchange from rock-weathering of the aquiferous formations in the area, dissolution and recharge from precipitation.
Water types are: CaSO4 and MgHCO3 in both seasons. Precipitation recharge, ion-exchange and simple dissolution are the processes determining groundwater character.
Hydrogeochemical facies are Ca-Mg-Cl-SO4 and Ca-Mg-HCO3.
All major ions concentrations are below WHO acceptable guidelines for both seasons.
Water quality indices: SAR, PI, %Na, KR and WQI, RSC and Wilcox diagram indicate that water in the study area is irrigation suitability assessment but of MAR were the values that are higher in Mile-1, Kumba road, Egbekaw, and Bachuo-Ntai rendering the water unfit for irrigation.
There is a need for more studies in order to determine the aquifer extent: lateral and vertical, aquifer boundaries, aquifer hydraulic parameters (permeability, transmissivity and storage capacity), the biological and organic water quality, necessary tools for a good management of this important resource in the aquiferous formations in Mamfe. These more detailed studies will throw more light on the groundwater capacity and residence time in the different aquiferous formations in the Mamfe Basin.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
None.
Akoachere, R. A. II, Eyong, T. A., Egbe, S. E., Wotany, R. E., Nwude, M. O., & Yaya, O. O. (2019). Geogenic Imprint on Groundwater and Its Quality in Parts of the Mamfe Basin, Manyu Division, Cameroon. Journal of Geoscience and Environment Protection, 7, 184-211. https://doi.org/10.4236/gep.2019.75016