Abstract
The Mubuku River catchment in western Uganda is highly sensitive to hydroclimatic variability, yet quantitative evidence linking rainfall anomalies to water quality degradation remains limited. This study presents a decadal (2014–2024) integrated assessment combining the Standardized Precipitation Index (SPI), rainfall deviation analysis, GIS-based spatial interpolation, and laboratory evaluation of physicochemical and microbial parameters. Results reveal significant temporal and spatial deterioration in water quality, with Total Dissolved Solids increasing by ~35%, hardness rising from 300 to 400 mg/L, and nitrate concentrations exceeding 50 mg/L at multiple sites. Microbial contamination also intensified, with fecal coliform counts increasing from 50 to 75 CFU/100 mL, surpassing WHO permissible limits. SPI analysis identified recurrent drought years (2014, 2016, 2023, 2024) alongside high-runoff periods, demonstrating a dual vulnerability framework where both precipitation deficits and excesses exacerbate contamination. Spatial analysis highlighted critical hotspots (WS4, WS6, WS8), where pollutant concentrations were 40–60% higher than the catchment average. The findings further indicate that drought conditions enhance mineral dissolution and baseflow contamination, while wet periods accelerate runoff-driven pollutant transport from agricultural and urban sources. This study contributes a novel climate–water quality linkage framework for tropical catchments by integrating hydroclimatic indices with spatial water quality assessment. The results provide actionable insights for targeted interventions, including hotspot-based management, seasonal regulation strategies, and improved wastewater control, to enhance water security and climate resilience.
Similar content being viewed by others
Spatiotemporal variability of surface water quality in tropical agriculture-dominated catchments: insights from water quality indices
Geospatial analysis of surface water and groundwater quality using GIS in Ishaka subcounty, Bushenyi District, Uganda
Comprehensive monitoring of the spatiotemporal variation of water quality and its associated human health risks in Luvuvhu river catchment, Vhembe biosphere reserve, South Africa
Acknowledgements
The authors appreciate the support and facilities provided by the Kampala International University, Western Campus, Uganda.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Ethics
This study was conducted in accordance with ethical standards and guidelines.
Consent to publish
The authors declare that there are no conflicts of interest regarding the publication of this paper.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Reprints and permissions
About this article
Cite this article
Yousuf, A.M., Krishnan, D. & Ukundimana, Z. Assessment of climate variability impacts on water quality using SPI and GIS approaches in the Mubuku River catchment, Uganda.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-58646-0
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-58646-0
Keywords
- Climate variability
- SPI
- WQI
- GIS
- Mubuku catchment
- Water contamination
Source: Resources - nature.com
