This study examines the impacts of climate change on irrigation water requirement (IWR) and yield for rainfed rice
and irrigated paddy at Ngamoeyeik Irrigation Project (NIP) in Myanmar. The future climate of the NIP area was projected using
the outputs of two General Circulation Models (GCMs) namely ECHAM5 (scenario A2 and A1B) and HadCM3 (scenarios A2
and B2) for future time period of 2020s, 2050s and 2080s. The climate change scenarios were downscaled to basin level by using
Statistical DownScaling Model (SDSM). Calibrated and validated AquaCrop v4.0 model was used to forecast the rainfed (MayOctober)
rice yield and irrigation water requirement for irrigated paddy (November-April) under future climate. The analysis
shows a decreasing trend in maximum temperature (-0.8 to +0.1°C) for the three scenarios and three time windows considered;
however, an increasing trend is observed for minimum temperature (+0.2 to +0.4°C) for all cases. The analysis on precipitation
also suggests that rainfall in wet season is expected to vary largely from -29% (2080s; A1B) to +21.9% (2080s; B2) relative to the
average rainfall of the baseline period. A higher variation is observed for the rainfall in dry season ranging from -42% for 2080s,
B2; and +96% in case of 2020s, A2 scenario. A decreasing trend of irrigation water requirement is observed for irrigated paddy in
the study area under the three scenarios indicating that small irrigation schemes are suitable to meet the requirements. An
increasing trend in the yield of rainfed paddy was estimated under climate change demonstrating the increased food security in the
region.