The Potential of Using Groundwater

The potential of groundwater

Groundwater has received much recent attention due its potential to meet the increasing demand for water, particularly for those who do not have surface waters nearby. Whilst Asia has a long tradition of groundwater use for agriculture (30% of rural households in China and 50% in India may be using groundwater for crop production) (Giordano, 2006), could Africa also divert towards this? Comparatively, only 1.5% of rural households in Africa use groundwater for crop production, so evidently figures show that Africa has missed this ‘groundwater revolution’.

Groundwater is of drinkable quality, thus does not need excessive or expensive treatment, and when in demand allows scaled development with infrastructure that is of lower cost compared to surface water infrastructure (Taylor et al, 2009). Groundwater is a way to take advantage of the changes induced by climate change, such as the increased variability of surface water resources and soil moisture. Evidence from a 55-year record of the Makutapora Wellfield in central Tanzania shows the highly episodic occurrence of recharge from the anomalously intense seasonal rainfall from the ENSO and the Indian Ocean Dipole mode of climate variability. These events interrupt multiannual recessions in groundwater levels, thus enabling water security for the groundwater community.

Figure 1 - Observational records of groundwater levels and rainfall over 55 years, from central Tanzania, (a) - Time series of groundwater level abstractions from 6 monitoring wells

(b) - Monthly rainfall (Taylor et al, 2013)

Evidence from the Makutapora Wellfield shows that the recharge in the aquifer occurs due to anomalously intense rainfall. Recharge does not occur unless the rainfall exceeds 200mm or the seasonal rainfall is greater than 670mm. This intense rainfall is required to overcome the high rates of evapotranspiration that are estimated to be around 160 mm month-1. This shows the potential of the role of groundwater as an adaptation strategy to climate change. Its qualities and recharge ability make it a water resource that can support the livestock economies in much of sub-Saharan Africa.

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