Abstract

Precipitation and air temperature records from 6 sites in Rwanda in the period from 1964 to 2010 are used for past/present climate assessment. Future climate projections (2010-2099) based on 3 general circulation models and 2 emission scenarios (A2 and B1) are used for climate projections. Precipitation, air temperature, and potential evapotranspiration based on ccma_cgcm3_1.1; miroc3_2medres and mpi_echam5.1 models are used in the analysis. Observed air temperatures suggested warming pattern over the past 40 years at an average of 0.35°C per decade. Rainfall records show no significant trend in the considered period. The potential evapotranspiration has an increasing trend and exceeds the precipitation in the months of June to September. Climate projections indicate trend towards a warmer and wetter climate. Increases in mean temperature are projected under all models and scenarios, while all models also indicate increases in annual rainfall totals. Despite of the projected wetter climate, the increase in potential evapotranspiration will overrule during the 21^st century resulting in deficit in water availability for the rainfed agriculture. Deficit periods in which potential evapotranspiration exceeds precipitation will be extended to 10 months at some parts in the country instead of 4 months at present.

Key words: Climate change, Rwanda, hillside irrigation, air temperature, precipitation, potential evapotranspiration.