Anthropogenic drivers of municipal water supply : Examining the impact on energy intensity in water utilities across countries in Africa

Abstract

Energy use for municipal water supply is often responsible for underestimated costs and carbon emissions. Meanwhile, infrastructure managers are struggling to keep up with population growth, economic development and the effects of climate change. Energy intensity of raw water extraction, drinking water purification and distribution depend on a host of supply-side drivers, while cumulative energy use rises with the volume of municipal water that water utilities must produce to meet growing demand. The present study is the first to link drivers of water availability, quality and demand to energy intensity in water utilities. The benefit of the following approach is that country-level impacts are measured as a compound of all identified human-caused drivers under consideration of their interdependencies and feedback mechanisms. A host of anthropogenic supply and demand-side drivers of municipal water and their interdependencies are identified, as well as how they feed into energy intensity in drinking water utilities. Based on the flow model that illustrates how identified drivers interact, ten key indicators are defined to measure levels of impact and country-specific sets of risks. The analytical framework based on these findings is applied to countries in Africa. A continent-wide high impact was found to be caused by competition for freshwater and polluting effluents from agriculture and to a lesser degree from industry. The results also suggest that demand for municipal water is expected to surge in most countries, while the high disparity between wastewater collection and treatment has a strong detrimental effect on surface water quality. The influence caused by drivers of water quality depends on the relative dependency on surface water or groundwater, which indicates the sources accessed for municipal water use. Finally, the countries were clustered according to similar combinations of impacts, where five clusters and three outlying cases were identified. Policymakers and water utility operators can incorporate these findings into their planning considerations in order to build resilient infrastructure and minimise the environmental footprint.