Abstract
This paper assesses the effect of climate change on reliability of rainwater harvesting systems for Kabarole district, Uganda, as predicted by 6 best performing global circulation models (GCMs). A daily water balance model was used to simulate the performance of a rainwater harvesting system using historical daily rainfall data for 20 years. The GCMs used to generate daily rainfall projections for 2025–2055 and 2060–2090 periods included; ACCESS1-0, BCC-CSM-1-M, CNRM-CM5, HADGEM2-CC, HADGEM2-ES and MIROC5. Analysis was based on the Ugandan weather seasons which included March, April, May (MAM) and September, October, November (SON) rain seasons in addition to December, January, February (DJF) and June, July, August (JJA) dry seasons. While an increase in reliability is predicted for the SON season, the worst-case scenario is projected during the MAM season with a reliability reduction of over 40% for the 2055–2090 period. This corresponds to a 27% reduction in water security for the same period. The DJF season is also expected to experience reduced water security by 1–8% for 2025–2055 and 2060–2090 with a 0.5 m3 tank size. Therefore, some form of extra harvesting surface and increased tank size will be required to maintain 80% systems reliability considering climate change.
Highlights
Competing global demands for water such as irrigated agriculture, climate change and population growth result in an increasing pressure on existing water resources to satisfy a demand that is approaching the limit of supply [1]
The results indicate that most households (73%) practice rainwater harvesting
This paper assessed the effect of climate change on reliability of rainwater harvesting systems for Kabarole district, Uganda using an ensemble of 6 best performing global circulation models (GCMs)
Summary
Competing global demands for water such as irrigated agriculture, climate change and population growth result in an increasing pressure on existing water resources to satisfy a demand that is approaching the limit of supply [1]. Global climate change estimates vary widely but most concur that some areas will have increased precipitation at the expense of other areas [2]. It is widely accepted that climate change will, among others, lead to an increase in the frequency and intensity of climatic extremes such as droughts and floods, some of the very elements that define climate variability [3]. Climate extremes such as strong El Niño events were predictable. With a warmer and drier climate predicted for Southern Africa, an increased frequency and intensity of. Shongwe et al [5]
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