Return flow analysis in large paddy rice irrigation scheme : Kibimba.
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Date
2026
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Busitema University
Abstract
The study analysed the irrigation return flow in the large paddy rice irrigation scheme at Kibimba, Uganda, where inefficient surface irrigation practices contribute to downstream waterlogging and deterioration of irrigation water quality. The main objective of the study was to analyse the return flow irrigation in the scheme through investigating return flow quantity, assessing return flow quality and modelling the relationship between return flow quantity and quality.
A mixed research approach involving field measurements, water quality assessment, spatial analysis and statistical modelling was adopted. Return flow quantity was measured using a discharge metre, while water quality parameters including temperature, dissolved oxygen, pH, turbidity, salinity, electrical conductivity and nitrates were assessed using a Hydrolab - H2O multiprobe sensor. ArcGIS 10.8, Irrigation Water Quality Index and multiple linear regression were used for data analysis and modelling.
The findings revealed a return flow coefficient of 33%, indicating substantial downstream waterlogging resulting from irrigation inefficiencies. The assessed return flow quality yielded an IWQI value of 100.38, classifying the water as unfit for irrigation due to quality degradation. Regression analysis further showed that 69% of the variation in return flow quality was explained by return flow quantity, with a strong positive correlation r, 0.830.
The developed model was statistically significant with p-values less than or equal to 0.05. The study concludes that sustainable management of irrigation return flow is essential for improving irrigation efficiency and minimizing downstream environmental degradation. Further research on treatment, recycling, and reuse of return flow for irrigation is recommended to enhance sustainable water resource utilization in paddy rice irrigation schemes.
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Citation
Makabuli, Y. (2026). Return flow analysis in large paddy rice irrigation scheme : Kibimba. [Unpublished dissertation dissertation]. Busitema University.