Introduction - How well are we talking about water and climate change?

UN Conference on Third World Population, Bucharest 1974, where the WSI was developed.

Hello! I am writing this blog about water and its relationship with environmental change in Africa. I have chosen to begin it by critically analysing the most widely used metric of water scarcity, and its ability to capture the rapid changes to these dynamics brought on by anthropogenic climate change. I hope to begin by providing myself a critical lens through which to view much of the conversation surrounding water scarcity in Africa.  

The Water Stress Index is the oldest and most widely used water scarcity indicator. Its key draw may be ease of use, requiring only population and freshwater volume in its simplest form. However, the prioritization of the link between the two factors has led to the widespread adoption of the Water Crowding Index. Especially in the context of climate change, a population-centric focus - more particularly, an overpopulation focus has been significantly criticised as a colonial attitude, blaming low-income nations for their inability to cope with the global climate change caused by wealthier countries, with some referring to the attitude as ecofascist. 

The WSI was designed to help warn for potential food insecurity, but has been extrapolated from this to operate at every scale, from continents to small towns. Its thresholds for stress and scarcity are also loosely based off patterns seen in Israel, and while Israel is semi-arid, its climate is vastly different to that of many nations in Africa, even those also classified as semi-arid, questioning the validity of the 1700 m³ capita⁻¹ year⁻¹.

WSI analyses are often based in river flow, with many using Mean Annual River Runoff to quantify freshwater availability, ignoring the role of groundwater and ‘green water’ in the water balance. Groundwater has been considered key to African water security, so disregarding it is damaging. However, ability to include groundwater and accurately capture its usage may be complicated by difficulty in quantifying it. While it is estimated 80% of Sub-Saharan Africa uses boreholes or wells, 2/3 of the labour force have smallholder farms, which are too small to pick up by conventional irrigation assessment (remote sensing), meaning that estimates of groundwater usage can be highly unreliable.  

The prevalence of annual averages also ignores the strong seasonality of Africa, exacerbation of which is a core impact of climate change. Neglect of the spatial scale is also important, with water availability sometimes widely varying across a region, especially those with less transmissive aquifers. The ability of changing climate to make alterations to the fundamental nature of flows is also not captured here, such as flood-driven sediment movement altering river courses.

Moving away from the aspects of the physical geography that WSI, a physically-based metric, cannot capture, it also assumes that water supply is the main source of water scarcity, ignoring the ability of those 'demanding' water to access supply. Nayebare et al, 2020 has recently shown that large amounts of water are mistakenly classified as uncontaminated, meaning their proximity to water is irrelevant to the ability of locals to use it. Other barriers to water access such as privatization are also ignored.

It also ignores the importance of the drivers of demand – lifestyle, infrastructure, migration, economy, technology etc. In fact, the African nations lowest in WSI, paradoxically often have higher access to water than those with abundant water resources, because of top-down interventions, as well as import of water.

Worryingly, the most popular measure of water scarcity is ineffectual in capturing the topic, and for use in expressing climate change resilience. Even just in the reading for this blog post, I have learnt an incredible amount about the dimensions of water stress in Africa, and am excited to continue doing so.