Assessing potential impact of climate change on irrigation requirement of coffee : a case study of Greater Luwero, Uganda

Abstract

Coffee irrigation enhances yields and contributes to the fight against poverty especially under Climate Change (CC). In Uganda, the impact of climate change on irrigation requirement of coffee is inadequately understood. This knowledge gap is critical for evidence-based policy development and the design of coffee irrigation systems. This study evaluates the impact of climate change on the irrigation requirement of coffee in the Greater Luwero between 2021 to 2080.The study objectives include; (i) to simulate climate variables for use in CropWat Model, (ii) to compute the irrigation requirement of coffee between 2021-2080 under RCP4.5 and RCP8.5, and (iii) to investigate the perception of coffee farmers to climate change. LARS-WG.6 was used to simulate climate between 2021-2080 under climate scenario RCP4.5 and RCP8.5. The simulated climate data was integrated into the CropWat.8 water balance model to analyze projected irrigation requirements. Additionally, a survey of 49 farmers was conducted to evaluate the farmers perception to climate change. Findings indicate significant changes in temperature and humidity but no significant change in rainfall and solar radiation for the study period P>0.05. Irrigation requirement under RCP4.5 increases from 668.06×104m3/ha/year to 1013.97×104m3/ha/year in Kiziba,703.73×104m3/ha/year to 985.87×104m3/ha/year for Katugo and 755.92×104m3/ha/year to 985.5×104m3/ha/year in Wakyato for the years 1991–2080. Under the RCP 8.5 climate scenario, irrigation requirements increase from 673.06×104m3/ha/year to 1049.74×104m3/ha/year in Kiziba,867.61×104m3/ha/year to 1116.54×104m3/ha/year in Katugo and 876.73×104m3/ha/year to 1070.18×104m3/ha/year in Wakyato. Survey results agree with the simulations projecting significant increase in coffee irrigation requirement between 2021-2080 in the region. Existing irrigations systems need to be upgraded to meet future water requirements. The study recommends adoption of drip irrigation over sprinklers to optimize water use efficiency. Additionally, Government should support coffee farmers in irrigation infrastructure development through grants and subsidies. Further research on climate-smart coffee irrigation is recommended in Uganda for improved farmers livelihood.