Therefore, I think the biggest challenges that ENSO can create for access to water are affecting water quality and the damages to the socio-economic structure of a population. This area may be less researched than the scientific side of ENSO and the direct output of El Niño/La Niña years (particularly rainfall), but it highly important for development and water management.
Last month, Unicef released a statement to emphasise the impact the El Niño winter and potential La Niña year could have on vulnerable communities. They summarised the threat to Africa as follows: "An estimated 11 million children are at risk from hunger, disease and lack of water in eastern and southern Africa as a result of a strengthening El Niño". Hunger, disease and adequate water for living are all linked back to having good access to safe water supplies. Firstly, as the previous blog post mentions, the variability of rainfall under ENSO conditions can cause problems for water availability for both domestic and agricultural use. If we are to expect more and more El Niño years, southern Africa must be prepared for droughts or else suffer a major shortage of water.
Secondly, waterborne diseases can be massively exacerbated by rainfall variability and contamination. The IPCC acknowledges that the frequency and duration of cholera outbreaks
are associated with heavy rainfall in, "with a possible association with the El Niño-Southern Oscillation", in western African and southern African countries. Cann et al. (2013) also studied weather events and waterborne diseases and suggest that "extreme water-related weather events" (such as El Niño) lead to the highest numbers of cases of waterborne illness. ENSO-related outbreaks of cholera were also highly linked to extreme water temperature change due to Vibrio cholerae having an increased growth rate at increased temperatures. In general, they summarised that extreme water-related events (one-off or recurring) represent a risk to public health. Further studies of specific countries and diseases, such as de Magny et al. (2012), Mendelsohn and Dawson (2008), Mabaso et al. (2006) and Kilian et al. (1999), all agree that increased rainfall due to ENSO seemed to result in higher incidence of waterborne diseases like cholera and malaria in Africa. This also seems to ring true in other parts of the world affected by ENSO, such as India and Sri Lanka. However, Patz et al. (2000) astutely reminds us all that ENSO is not responsible for all epidemics, such as the Ethiopian epidemics in 1953 and 1958, neither of which were El Niño years. In fact, Patz and Lindsay (1999) argue that in some cases, heavy rainfall could even wash larvae from breeding sites, thus reducing the incidence of malaria. Regardless of the patterns of disease, it is obvious that when water sources are contaminated (such as with cholera), or when incidence of other diseases are high, it is difficult for that population to have adequate access to safe water for use.
Thirdly, ENSO can also indirectly affect access to water through socio-economic and health issues. For example, severe droughts from ENSO conditions can lead to increased malnutrition and a threat to food security, which results in difficulty accessing safe water (as one can see, this is a vicious loop as little access to safe water can lead to problems that result in a decreased ability to ensure a safe water supply for oneself). Food security is a particularly important aspect that can be adversely affected by ENSO through highly variable rainfall for agricultural production. If water availability for agriculture is reduced, domestic consumption may be sacrificed in order to meet food demands, thus reducing access to safe water. Cane et al. (1994) used sea surface temperature to forecast maize yield in Zimbabwe and found that there was a strong correlation between the El Niño Index and maize yields, so much so that it correlated stronger than the El Niño Index and rainfall did. They found that more than 60% of the variance in maize yield in Zimbabwe was accounted for by sea surface temperatures in the eastern equatorial Pacific Ocean - where El Niño conditions are created.
Other socio-economic impacts of ENSO, other than health and food, include the economy, education and infrastructure. Cashin et al. (2015) conducted a study of the macroeconomics of El Niño, observing that South Africa (among many other countries such as Chile, Indonesia and Australia) see a "short-lived fall in economic activity" as a response to a typical El Niño event. This is mainly due to the increased in temperature and persistent dry conditions of El Niño, which impact agricultural production (which makes up 10% of South Africa's GDP). In addition, after particularly strong El Niño (and to some extent, La Niña) events, there may be other costs, such as the estimated $1.8 billion in damages of infrastructure and property in Kenya following the 1997-1997 El Niño flooding. And it isn't just flooding or droughts that cost money; ENSO can influence storms across Africa that can also contribute to costs. Donnelly and Woodruff (2007) show that while a strong El Niño year can hinder hurricane development through increased vertical wind shear, a strong La Niña year could increase North Atlantic hurricane activity. Damages to the economy can result in reduced access to water, particularly in the users are reliant on paying for water through vendors or kiosks. Infrastructure damage not only hinders access to water through costs but through the potential to damage water supply systems, roads to access water supply/health treatments, and other vital components of having an adequate supply of safe water to live. ENSO can also affect education through damage to infrastructure, limiting the ability of people to access areas, or in the worst cases, transforming school facilities into emergency shelters due to extreme events like floods. Education is not only vital for development, but it can contribute to improving access to water through NGOs like Water Aid, whose educational element is an important part of improving access to safe water in a sustainable manner.
Finally, the threats of ENSO conditions can leave many families crippled through deaths that could be related to floods, mudslides, famine, storms, or through separation due to a need to seek work elsewhere. Unicef emphasises that this could leave children vulnerable, as well as putting pressure on them to source water. Fewer members in a family evidently reduces access to water and further exacerbate all the problems already mentioned.
It can be very disconcerting to think about how ENSO events can impact the real ability of populations to access safe water and lead their everyday lives. Weather and climate are perhaps the most important aspect of water resources and it is therefore incredibly useful to have good prediction and forecasting systems in place to understand the potential impacts of ENSO on different regions around the world. I've really enjoyed learning about this and I think it's a positive sign that El Niño is becoming a more discussed topic in news and mainstream media and not just in the scientific and academic community. Hopefully our understanding of ENSO (not just El Niño but also La Niña!) continues to improve so we can better plan and mitigate for future ENSO events.
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