Hydrochemical and isotopic characteristics of groundwater in the Ndop plain, northwest Cameroon: resilience to seasonal climatic changes

Wirmvem, Mengnjo Jude; Ohba, Takayoshi; Suila, Justice Yuven; Fantong, Wilson Y.; Bate, Nchemty Oscar; Ooki, Seigo; Wotany, Engome Regina; Asaah, Asobo Nkengmatia Elvis; Ayonghe, Samuel N.; Tanyileke, Gregory; Hell, Joseph Victor

doi:10.1007/s12665-014-3265-y

Cited by 6 publications

(9 citation statements)

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“…Since the dvalues of the groundwater, streams, and rivers are not significantly affected by evaporation, the dominant recharge period is likely from the abundant May to June monsoon rains. This have earlier reported in the area (Wirmvem et al 2014a). A minor amount of recharge occurs during October-November post-monsoon showers.…”

Section: Discussionsupporting

confidence: 73%

“…While the semi-arid regions of Sub-Saharan Africa (Adanu 1991;Favreau et al 2009;Fantong et al 2010;Lutz et al 2011) and Equatorial regions of East Africa (Nkotagu 1996;Taylor and Howard 1996;Owor et al 2009;Taylor et al 2013a) show recharge by the heaviest monsoon rains, only the abundant (and not the heaviest) monsoon rains recharge groundwater in Equatorial West Africa (Mbonu and Travi 1994;Oga et al 2008;Wirmvem et al 2014a). The disparity may be due to varied hydrological conditions (under a changing climate) including sources and atmospheric circulation of moisture (Taupin et al 2000).…”

Section: Discussionmentioning

confidence: 99%

“…The weathered basement (regolith) and alkali-rich fluvial sediments constitute the shallow aquifer material in the plain. Percolation of water through the unconsolidated sediments forms the groundwater aquifer system with depths less than 30 m below the surface (Wirmvem et al 2013(Wirmvem et al , 2014a. Numerous rivers and streams discharge dendritically from the flanks of the mountainous chain facing the plain and recharge the Bamendjin dam (Fig.…”

Section: Geology and Hydrogeologymentioning

confidence: 99%

“…Groundwater recharge studies in the semi-arid regions of Sub-Saharan Africa (Adanu 1991;Favreau et al 2009;Fantong et al 2010;Lutz et al 2011) and Equatorial East Africa (Nkotagu 1996;Taylor and Howard 1996;Owor et al 2009;Taylor et al 2013a, b) have reported recharge by heaviest and isotopically depleted monsoon rains. However, in groundwater recharge studies in the equatorial West Africa, recharge is by abundant but relatively less depleted rainfall events (Mbonu and Travi 1994;Oga et al 2008;Wirmvem et al 2014a). Similarly, different recharge rates have been reported across SubSaharan Africa (Taylor and Howard 1996;and references therein;Fantong et al 2010;Takounjou et al 2011;Yidana and Chegbeleh 2013).…”

Section: Introductionmentioning

confidence: 99%

“…As reported, the major ion chemistry of the groundwater in the area is within the WHO guidelines (Wirmvem et al 2013). The meteoric origin, recharge timing and resilience of the groundwater to short-term climatic changes have been described (Wirmvem et al 2014a). However, there is a lack of additional hydrological information (based on dense sampling) including the recharge rate and residence time of the groundwater for its management.…”

Section: Introductionmentioning

confidence: 99%

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Shallow groundwater recharge mechanism and apparent age in the Ndop plain, northwest Cameroon

et al. 2015

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Knowledge of groundwater recharge and apparent age constitutes a valuable tool for its sustainable management. Accordingly, shallow groundwater (n = 72) in the Ndop plain has been investigated using the stable isotopes of oxygen ( 18 O) and hydrogen ( 2 H or D) and tritium ( 3 H) to determine the recharge process, timing and rate of recharge, and residence time. The shallow groundwater showed low variability in d18 O values (-2.7 to -4.1 %) and 3 H content (2.4-3.1 TU). The low variability suggests a similar origin, homogenous aquifer, good water mixing and storage capacity of the groundwater reservoir. Like surface water, a cluster of groundwater along the Ndop Meteoric Water Line (NMWL) and Global Meteoric Water Line indicates meteoric origin/recharge. The rainfall recharge occurs under low relative humidity conditions and negligible evaporation effect. About 80 % of the recharge is from direct heterogeneous/diffuse local precipitation at low altitude (\1,260 m) within the Ndop plain. Approximately 20 % is from high altitude precipitation (localised recharge) or is recharged by the numerous inflowing streams and rivers from high elevations. A homogenous cluster of d-values in groundwater (and surface water) between May and June monsoon rains on the NMWL suggests dominant recharge during these months. The recharge represents at least 16 % ([251 mm) of the annual rainfall (1,540 mm) indicating high annual recharge; high enough for development of the groundwater resource for agriculture. The 3 H content ([2.4 TU) in groundwater indicates post-1952 recharged water with an estimated residence time \30 years, suggesting short subsurface circulation, and subsequently a renewable aquifer.

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Section: Discussionsupporting

confidence: 73%