According to research findings, due to global warming, an increase in the
average temperature has been observed in the mountainous areas of the world, including
the northern part of Thailand, and this is likely to affect water resources. This study
aims to investigate the impact of climate change on the variations in temperature and
rainfall in Mae Rim watershed (MRW), a tributary of Ping River in Northern Thailand
under the progress of A2 and B2 emission scenarios during 2015–2074, and to review
and evaluate the water conditions in future climate scenarios in the watershed, with an
emphasis on rain fed agriculture. The results indicated that, in both A2 and B2
scenarios, maximum and minimum temperature (Tmax and Tmin) during the 2045–
2074 period will be higher than the 2015–2044 period, and the Tmin under A2 scenario
will be greater than the B2 scenario. As for rainfall conditions, less changes are
expected to be found in the rainy season, but there is likely to be an increasing trend in
the dry season. Upon using the drought indices of the generalized monsoon index
(GMI) and the standardized precipitation index (SPI) to evaluate for the water condition
in the watershed, it was found that SPI and GMI values under both A2 and B2 scenarios
followed a similar trend. The drought events in the 2015–2044 period were found to be
greater than the 2045–2074 period.
Key words: Temperature/ Rainfall variability/ Generalized Monsoon Index (GMI)/
Standardized Precipitation Index (SPI)/ Water condition