Groundwater Case Study Assessment

As discussed, groundwater varies hugely throughout Africa. As does population, socioeconomic position and demand for water. Therefore, each case for groundwater needs to be judged individually, a mammoth task. The inherent variability means that traditional proxies are actually quite ineffective as different variables carry different weightings for different regions.

Pavelic et al. have published a book assessing 'Groundwater availability and use in Sub-Saharan Africa: A review of 15 countries'. In the book they take fifteen country scale case studies: Burkina Faso, Ethiopia, Ghana, Kenya, Malawi, Mali, Mozambique, Niger, Nigeria, Somalia, South Africa, Tanzania, Uganda, Zambia and Zimbabwe. If anyone has a particular interested in any of the case studies I'd definitely go over them, on average they're only about 20 pages and all written by country experts.

In later posts I'm going to analyse groundwater in Ghana, a country I have a specific interest in  I've spent time in Ghana doing charity work and observed groundwater pumps and rainwater collection schemes.

The conclusions of Pavelic et al's book are as follows, note how they do fall into the trap of trying to assign a score or a proxy measure to such water resources just analyse each on their own merit:

Through not ranking these issues, the book highlights the problems each country has with harnessing groundwater without comparing them.

Groundwater Availability

On my last post I received a question about the availability of groundwater supplies, and then whether they were expensive.

The volume of groundwater stored in Africa is estimated to be 0.66million km3, more than 100 times annual renewable freshwater resources, and 20 times the freshwater stored in lakes. This is why groundwater is seen as a potential buffer to climate variability and change.

Let me set the scene of groundwater in Africa. The inconsistency of groundwater distribution is huge; regarding the variability in groundwater storage, recharge, depth and aquifer productiveness.

To illustrate this, MacDonald et al. released a brilliant paper in which they map groundwater resources in Africa. The reason I'm fond of papers such as this is the production of maps means their research can easily be consumed by a wider audience outside of academia, something I myself am hoping to achieve with my blog. If the aim of geographical research is to inform policy change, then the spread of knowledge to inform opinion outside the sphere of academia can have a major impact, and this paper achieves that. Below are three of the maps from MacDonald et al.'s paper.
 

Groundwater storage for Africa in mm, with modern annual groundwater  recharge added for comparison from Doll and Fiedler  groundwater modelling.

Aquifer productivity for boreholes appropriately drilled and sited using appropriate techniques and expertise. The inset shows  the depth to groundwater, from Bonsor and MacDonald.

Panel (a) is the proportion of land area within each geological category that is attributed to a particular class of aquifer productivity, and panel (b) shows the distribution of said categories throughout Africa.

These maps show the need for individual case study assessments before an African country should decide whether to use groundwater. I will take this further my studying some specific groundwater cases in my next post.

Groundwater as a solution?

Rainfall patterns in Africa are set to increase in variability with climate change. Furthermore, increased temperatures mean air holds more water before saturating and therefore rainfall events are going to be less frequent and heavier. With these changes, Africa needs to adapt to climate change.

Stephen Ngigi (2009) proposes that groundwater could aid smallholders in adapting to such increased climate variability. Smallholders are the poorest farmers, generally owning less than two hectares of land. Not only can smallholder irrigation help climate change adaption, but it can promote poverty alleviation, labour productivity, general economic development and rural employment (Villhoth, 2013). Villhoth excellently summarises the current knowledge regarding groundwater irrigation for smallholders, which makes up the majority of sub-Saharan Africa's employment and agricultural produce. However, as a summary of so many groundwater thematic-areas in only 32 pages it is limited in detail.

So why can groundwater help? Farmers tend to favour groundwater because of its consistently. Due to the nature of the ITCZ's annual variability, rivers in Africa tend to be much less consistent than elsewhere on the planet (see three selected rivers below).

Taylor (2006), Chapter 8

Such variability makes groundwater attractive to smallholders due to autonomy over its control. Therefore, risk is lower, outputs are more stable and productivity increases (Villhoth, 2013). In Northern Ghana Dittoh et al. (2013) found that manual groundwater irrigation produced an average gross revenue per hectare of $884.87, compared to $618.22 for manual surface water irrigation.

Groundwater produces a constant supply of water to smallholder farmers in a region with unmatched climate variability, problem solved? Not quite. These groundwater resources are not necessarily renewable or sustainable. These fossil groundwater systems have been created by historic rainfall and regeneration rates from contemporary water generation are tiny compared to the potential extraction... perhaps sounds similar to another resource we use?

Already over 80% of domestic rural water supplies in sub-Saharan Africa are from groundwater, and South East Asia has proven what groundwater abstraction can do to agricultural productivity. The added control over supply is the clear benefit and explains the drive for groundwater pumps, but are they a sustainable solution? I'll be looking into the sustainable feasibility of groundwater pumps in Africa in a later post.

Source

Combined Climate Change Risk

In my previous three posts I have summaries the three main risks climate change poses to Africa: changing rainfall patterns, adaptability and temperature increase.

It is this the combined climate risk of this three-faced threat that puts African life and development in such danger, perhaps if only one of these problems was occurring it could be dealt with. Although I've posted it previously, this IPCC summary clearly illustrates what Africa is up against.

To aid Africa the developed world must try and keep climate change to a minimum through lowering emissions and provide help to increase Africa's adaptability. Having established the problem, I will now post about how Africa might look to deal with the issue.

Climate Change Risks: Temperature Change

Global temperatures have already risen by 0.85 degrees, and are predicted to rise further. Below is a projection of four carbon dioxide emission scenarios and the temperature increases that will result: low, medium, medium-high and high emissions.

Source

The low emission scenario is extremely unlikely requiring co-operated global mitigation on a huge scale. Whichever of the other three emissions scenario occurs it will have profound impacts on much of Africa. This is because a temperature increase will increase evapotranspiration, obvious right? But in water scare regions, like large sections of Africa, the impact of this can be devastating.

For example, if rainfall is 1200mm and evapotranspiration equivalent to 1000mm in a given catchment, flow will be 200mm. A 10% rise in evapotranspiration to 1100mm will then reduce flow 50% to 100mm. This is a similar relationship to how I describe when considering changing rainfall patterns.

The above scenario that best represents future climatic conditions is up to humans and how we managed our emissions. The smaller the temperature change the easier job Africa will have, but the increase in evapotranspiration will have major impacts on future water supply.

Climate Change Risks: Adaptability

Africa is also particularly at risk due to its adaptability.

The UNEP predicts 'no continent will be struck as severely by the impacts of climate change as Africa'. This is partially down to increasing climate and rainfall variability, as well as an increased risk of natural disasters. The situation is exacerbated by Africa's relatively limited adaptive capacity. Brooks, Adgar and Kelly rank countries on their adaptive capacity based on eleven key indicators that exhibit a strong relationship with climate-related deaths. They found that 'the most vulnerable nations are those situated in sub-Saharan Africa'. The relative lack of development and poverty that's widespread in Africa greatly exacerbates the climatic changes that will take place. This is very apparent in many common scenarios: when California declared a drought state of emergency in January they continued to import water with the 398km long Colorado River Aqueduct and enforced restrictions, whereas the Horn of Africa drought of 2011 resulted in tens of thousands of deaths. 

Colorado River Aqueduct, Source

The situation in areas of Africa are such that climate change is a threat to the survival of populations and long-term wellbeing. The effort to sustainably develop Africa, first through the MDGs and now the SDGs, is at risk from climate change. Africa's socio-economic situation makes it very difficult to combat such a risk, and if we do not act 'its population, ecosystems and unique biodiversity will all be the major victims of global climate change' (UNEP). Below is a summary of the risks that could cause such consequences:

Climate Change Risks: Rainfall Patterns

So having established that climate change is not Africa's fault but it will be the most affected, we have to establish how it will be affected.

One of the major effects on Africa due to climate change will be alterations in precipitation regime. In his paper for Environment International on what we know about changing rainfall patterns Mohammed Dore observes:

'That wet areas become wetter, and dry and arid areas become more so. In addition, the following general changing pattern is emerging: (a) increased precipitation in high latitudes (Northern Hemisphere); (b) reductions in precipitation in China, Australia and the Small Island States in the Pacific; and (c) increased variance in equatorial regions.'

Applying this to Africa would mean increased variance over the majority, which has negative implications for water management, the tropical areas have higher rainfall and the drier have lower. In other words, the weather becomes more extreme. Allan et al. observes that in the 30% of wettest tropical areas rainfall will increase by 1.8%/decade, and in the driest 30% of tropical regions will decrease by 2.6%/decade (calculated using the GPCP with data from 1988-2008).

Unfortunately for dry or tropical regions (majority of SSA) rainfall decreasing 2.6%/decade does not mean water decreasing 2.6%/decade. De Wit and Stankiewicz studied what falling rainfall would mean for surface water in Africa, and it makes for fairly grim reading. Across Africa, a 10% fall in rainfall would reduce surface water by 17-50%. This nonlinear response is particularly worrying. The table below is an extract from their work, with Tulear, Mogadisu and Jenouba's perennial drainage all dropping to an alarming 0% of current levels with a 10% drop in precipitation.

De Wit and Stankiewicz