A tool for measuring environmental resilience to floods in Tanzania water supply systems

Water supply systems (WSSs) are particularly the central recipient of the impacts of environmental-related risks. Most heat energy trapped by greenhouse gases (GHGs) goes into water bodies and often affects the water cycle leading to severe floods. Floodwater flowing through a polluted and degraded environment contaminates the water sources contributing into elevated treatment costs. Resilient WSSs would survive those impacts. Yet, existing resilience tools have paid less attention to environmental aspects during the assessment, focusing on the physical elements making up the system. In this paper, a qualitative environmental tool to assess WSSs resilience is proposed. The tool's principles and indicators are made appropriate to Tanzania through a Delphi survey. Thematic and standard descriptive analyses are carried out during data analysis. Environmental resources sensitivity, environmental capacity, natural flood attenuation, and natural assets are the main factors that affect the WSSs environmental resilience. When evaluated in a real case WSS, the tool showed the WSS has moderate environmental resilience with less than desirable performance where specific improvements are required for 78% of the aspects. Results are useful contributions for planning and implementing measures to improve the WSS environmental resilience.