Assessment of the Impact of Climate Change on Water Supply Demand and Water Supply Distribution Network in Kiboga Town in Uganda

Abstract

This research study presents an assessment of the impact of climate change on water demand and water distribution network in Kiboga water supply system in Uganda. The objectives of the study were to establish monotonic trends, assess the future climate change, potential urban water demand variability and the reliability of the Water Distribution Network (WDN) in the face of climate change. Monotonic trends were established using Mann Kendall test. Future rainfall and temperature changes for the future periods were projected using General Circulation Model outputs (GFDL-ESM4 for precipitation and MPI-ESM-1-2-LR for temperature) downscaled with SDSM software, for two Shared Socio-economic Pathways. Future urban water demand variability due to climate change was assessed using linear regression. The climate change impact on the reliability of the WDN was assessed using a new Climate Change Impact Index based on the Resilience Index (RI) of the WDN. The results for monotonic trends showed non-statistically significant mixed trends for precipitation, positive trends in maximum temperature but with no statistical significance for most months while minimum temperature exhibited non-statistically significant upward trends for all months of the year. In terms of future climate change, the results indicated that precipitation will reduce by 8%-55% 10%-55% and 7%-52% in the 2021-2040, 2041-2060 and 2081-2100 periods respectively, under SSP245 and SSP585. Maximum temperature will increase by up to 2.75°C, 3.35°C and 2.70°C in the 2021-2040, 2041-2060 and 2081-2100 periods respectively, under SSP245 and SSP585. Minimum temperature will increase by up to 2.10°C, 2.20°C and 2.38°C in the 2021-2040, 2041-2060 and 2081-2100 periods respectively, under SSP245 and SSP585. Monthly urban water demand is projected to increase by up to 10.8%, 11.2% and 30.8% in the 2021-2040, 2041-2060 and 2081-2100 periods respectively, under SSP245 and SSP585. The reliability analysis of the WDN indicated that the MRI of the entire network reduced slightly by 0.053. The Climate Change Index for the WDN was 0.973 indicating that the water supply system design used sufficient design factors to mitigate demand uncertainties including climate change, that may arise during the lifespan of the water supply system. The study presents a robust approach for assessing how climate change may affect urban water demand and WDN and provides crucial information to decision makers to modify demand projections while taking into account climate change impact assessments.