If you have not noticed, this summer has been hot and dry. Very hot and very dry.
The cumulative rainfall in 2022 up to the beginning of August has been the third lowest since records began, dryer than 1996, 2006, and 2018. In terms of cumulative maximum temperatures over the same period, 2022 is the hottest summer ever recorded. The impact on the water industry has been tough, and will be for a while until water resources are able to replenish. Many water companies had to enforce hosepipe bans and limitations on water use, affecting the Greater London area, Thames Valley, Surrey, Kent, Sussex, Gloucester, North Wiltshire, Hampshire, Isle of Wight, Yorkshire, Cornwall, Northwest Devon, Isle of Man, Pembrokeshire, and parts of Carmarthenshire (so far).
This has generated a rather political debate on water companies’ management, their reaction to drought conditions, and how money is invested for preparedness. We will not join the debate, but we can look at the data side of the problem. According to best practices, most of demand forecasting has historically been based on linear models or techniques based on linearity (meaning that we expect things to keep the same trend in the future as they had in the past, under similar conditions). This is a simple and transparent way of modelling, easy to understand and implement, and works rather well in many contexts. However, climate change is not one of them. Although some seasonality and peak analysis are performed using non-linear techniques, they are often based on past observations, planning future droughts like the ones that happened in the past. We know that climate change is happening, and it is not happening linearly. To explain it in simpler words, if we plan water resources according to best practices, we expect droughts and extreme conditions to occur in the future with the same frequency as they happened in the past. This is not the case.
Another key error we make is to assume that water consumption will increase linearly with hot and dry conditions. This may not be the case. The increase of 1°C from 24°C to 25°C has a different impact on consumption than an increase from 32°C to 33°C, which is still very different compared to an increase from 38°C to 39°C. If conditions are comfortable, our water consumption habits continue as normal. When we start to feel uncomfortable, we take more and more measures to mitigate the heat, many of these are water-intensive (paddling pools, frequent showers, AC). Similar behaviours happen with dry conditions, as we start to water gardens and lawns that we would not need to water normally.
Therefore, while we should discuss how to best invest money in our water infrastructure, we should also plan water resources with a more realistic view of how likely extreme conditions and extreme consumption will be in the future. At Artesia, we can both consider non-linearities in climatic extremes (thanks to our expertise in statistics, machine learning, and climatic sciences) and analyse the complexities of people’s reaction to heatwaves and droughts (thanks to our expertise in social science). Although this is not currently required by regulations and best practices, we can offer a more realistic view on what the future will look like for the water industry.
