CLIMATE CHANGE IMPACT ASSESSMENT ON WATER RESOURCES OVER
THE EAST ASIA MONSOON REGION
Bae, D.-H.1, Lee, M.-H.1, Kim, J.-B.1
1
Sejong University, Seoul, Korea
Backgrounds of this study
Asia monsoon plays an important role on global water circulation and provides substantial
precipitations and water resources to the people living within the domain. It provides many benefits,
but also causes series flood and drought problems. Of course, there are various reasons for these
water-related disasters, but the current climate change makes much more complicate and difficult
to manage them. The objectives of this study are to evaluate the climate change impact
assessments on water resources over the East Asia monsoon region and to find out the highly
susceptible zones of climate change.
Methods
There are two approaches for the climate change impact assessments on water resources (Figure
1). One is the analysis of past hydro-meteorological data to detect some climate change trends.
The other is the use of GCM outputs with downscaling and hydrologic models under the future
greenhouse gas emission scenarios.
Figure 1. General process of climate change impact study on water resources
For the analysis of past historical data, Mann-Kendall statistical test was used to determine the
significance of trends in precipitation and runoff data. The 0.5 degree precipitation and temperature
data of APHRODITE were used for the trend analysis and the input of hydrologic model to derive
the model-driven runoff data.
For the future projections over the area, GCM simulations with downscaling scheme and hydrologic
model were used. The climate projections, the outputs of GCMs, were used for generating Multi
Model Ensemble (MME) scenarios and for evaluating the difference for hydro-meteorological
variables on the future 3 periods (called 2020s, 2050s and 2080s) relative to the past 30-year
reference period. The VIC model was employed for analysis of hydrology data (Nijessen et al.,
2001).
Results
Mann-Kendall test was applied to 30-years (1977-2006) of temperature, precipitation and runoff
data in the study area. The test statistics were computed for each grid point and the spatial
distribution of trends was obtained (Figure 2). The results show increasing (↑) and decreasing (↓)
trends with 90% and 95% significance levels. They indicate that over the past 30 years, the average
temperature increased approximately by 0.27℃/decade. This estimated increase is substantially
high compared to global temperature increase of 0.13℃/decades (IPCC, 2007). The average
annual precipitation was observed to decrease by 86.5 mm over the 30-year period. Especially
significant decreasing trends of precipitation appeared over the Tibetan Plateau, Indonesia, inland
India and southern Far East Russia, while increasing trends were observed over northwest China,
north Pakistan, eastern Afghanistan and Korea. The average annual runoff was decreased by
approximately 41.8 mm over the same time period. The spatial distribution of runoff trends was
similar to that of precipitation trends.
Figure 2. Mann-Kendall test results of annual historical temperature, precipitation and runoff
The changes projected in temperature, precipitation and runoff at future periods relative to the
reference period are shown in Figure 3. The average temperature was expected to increase by
0.9℃, 2.1℃ and 3.7℃, while average precipitation by 1.8%, 4.6% and 10.7% in 2020s, 2050s and
2080s, respectively. The precipitation was projected to significantly increase over the southwest
region of South Asia and decrease over the bordering regions of South Asia and East Asia. The
1.5%, 3.9% and 11.1% increase in annual mean runoff by future 3 periods were projected. The
spatial distribution of future runoff change was similar to that of precipitation.
Figure 3. Relative change of temperature, precipitation and runoff by 2050s
Conclusions
The results in this study showed change with high spatial variation such as increase in precipitation
and runoff over some regions and decrease over other regions of Asia. Further research needs to
be carried out to identify the deriving factors of these variables. Moreover, the projected change
may result in positive or negative impacts over different regions that urge the need of detailed
regional impact assessment and adaptation studies over vulnerable areas to alleviate future climate
change-induced disasters.
Acknowledgement
This work was jointly supported by the APN and a grant (14AWMP-B082564-01) from Advanced
Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of
Korean government.
References
IPCC. (2007) Climate Change 2007: The Physical Science Basis. Contribution of WG I to the fourth
assessment report of the Intergovernmental Panel on Climate Change. Cambridge University.
NIJSSEN, B., LETTENMAIER, D.P., LOHMANN, D. & WOOD, E.F. (2001) Predicting the discharge of global
rivers. Journal of Climate. 14 (15). p. 3307-3323.