Author(s): Weerayuth Pratoomchai; So Kazama; Naota Hanasaki; Chaiwat Ekkawatpanit; Daisuke Komori
Linked Author(s): So Kazama
Keywords: Climate change; CMIP5; Global Climate Models; Groundwater
Abstract: Climate change and its impacts on water resources are unequivocal and occur globally. There is a 95%consensus among the scientific community that human activities contributed to climate change and altered water resources. This study, we focused on a regional scale climate change impact assessment on water resources in the Upper Chao Phraya River basin (UCP) in Thailand in 2 periods (near future (2026-2040) and far future (2076-2090) ) using 5 Global Climate Models (GCMs) under 3 greenhouse gas emission scenarios term Representative Concentration Pathways (RCPs) -low (RCP2.6), intermediate (RCP4.5), and high (RCP8.5) scenarios. According to the projections, we found relative surface air temperature will increase by 1.45 (1.70), 1.48 (2.25), 1.80 (4.43) °C in the near (and far) future under the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. Rainfall is projected to decrease especially from May to August for both projected periods. The relative changes between the reference period (1986-2000) and the projection periods of groundwater recharge will reduce by 13 to 17%and by 13 to 19%in the near future and far future, respectively. Maximum groundwater storage was estimate to reduce by 1.6 (near future) and 1.7 (far future) km3 upon reductions of the recharges by 18.3 and 20.2 mm, respectively. Despite the future projections still have uncertainties, but they are useful for framing the probable potential impact ranges and warning for future water resources management.