Analysis of the impacts of irrigation water management practices and climate change on water availability for rice production. A case in Uganda

抄録

Water, food, energy and climate have intrinsic relations. Worldwide, climate change has negatively impacted water resources and rice production. The vast majority of climate change impacts on rice production range from unpredictable rainfall patterns, floods, landslides, the high temperature which affects reproductive and development stages of rice and thereby causing a decrease in plant height and root elongation, and the increased use of pesticides. As a developing country, Uganda is highly vulnerable to climate change despite its insignificant contribution to global warming. With the current annual population increase of 3.32%, the role of agricultural water management in ensuring food security cannot be ruled out.

Rice cultivation in Uganda is carried out on large and small-scale irrigation schemes managed by the government and small-holder farmers. The irrigation method is mainly traditional flooding which wastes water as compared to other irrigation practices. Additionally, rice production requires a lot of water, both sunny and wet conditions during cultivation periods since its yield is strongly affected by weather and water availability.

While the country is suitable for rice cultivation, the demand for water for agricultural production would double with the current climate change. To secure rice production and productivity in Uganda, the dwindling water resources, and increased climate unpredictability should be matched with a shift from business as usual to climate-smart irrigation practices. These include among others alternate wetting and drying, dry seeding, monitoring of soil and weather conditions, etc. Water productivity has diverse benefits such as food production, and reduction of greenhouse gas emissions, groundwater recharge, carbon sequestration and ecological services.

Further, the impacts of irrigation practices, water management, and drainage in paddy rice fields are less documented, calling for questions into the sustainability of current irrigation water management practices.

Given the background above, the paper analyzes the history of irrigation and water resources developments, management practices especially for paddy rice in Uganda. Further, we look into the climate change impacts on rice yields, existing studies on how farmers are adapting, and the need for integrated soil and water management practices.