Projecting changes in the frequency and intensity of future
precipitation and flooding is critical for the development of social
infrastructure under climate change. The Mekong River is among the world's
large‐scale
rivers severely affected by climate change. This study aims to define the
duration of precipitation contributing to peak floods based on its correlation
with peak discharge and inundation volume in the Lower Mekong Basin (LMB). We
assessed the changes in precipitation and flood frequency using a large
ensemble Database for Policy Decision‐Making
for Future Climate Change (d4PDF). River discharge in the Mekong River Basin
(MRB) and flood inundation in the LMB were simulated by a coupled rainfall‐runoff
and inundation (RRI) model. Results indicated that 90‐day
precipitation counting backward from the day of peak flooding had the highest
correlation with peak discharge (R² = 0.81) and inundation volume (R² = 0.81).
The ensemble mean of present simulation of d4PDF (1951–2010) showed good
agreement with observed extreme flood events in the LMB. The probability
density of 90‐day
precipitation shifted from the present to future climate experiments with a
large variation of mean (from 777 mm to 900 mm) and standard deviation (from 57
mm to 96 mm). Different patterns of sea surface temperature (SST) significantly
influence the variation of precipitation and flood inundation in the LMB in the
future (2051–2,110). Extreme flood events (50‐year, 100‐year, and
1,000‐year
return periods) showed increases in discharge, inundation area, and inundation
volume by 25–40%, 19–36%, and 23–37%, respectively. This article is protected
by copyright. All rights reserved.
Climate change currently
affects the resilience and aquatic ecosystem. Climate change alters rainfall
patterns which have a great impact on river flow. Annual flooding is an
important hydrological characteristic of the Mekong River Basin (MRB) and it
drives the high productivity of the ecosystem and biodiversity in the Tonle Sap
floodplain and the Mekong Delta. This study aims to assess the impacts of
climate change on river flow in the MRB and flood inundation in the Lower
Mekong Basin (LMB). The changing impacts were assessed by a two-dimensional
rainfall-runoff and inundation model (RRI model). The present climate
(1979-2003) and future projected climate (2075-2099) datasets from MRI-AGCM3.2H
and MRI-AGCM3.2S models were applied with a linear scaling bias correction
method before input into the RRI model. The results of climate change suggested
that flood magnitude in the LMB will be severer than the present climate by the
end of the twenty-first century. The increment of precipitation between 6.6 and
14.2% could lead to increase extreme flow (Q 5) 13-30%, peak inundation area
19-43%, and peak inundation volume 24-55% in the LMB for ranging of
Representative Concentration Pathways (RCP) and sea surface temperature (SST)
scenarios while there is no significant change on peak flood timing.
