poster - International Conference of Agricultural Engineering

The data in Fig. 5 shows that the REIC was better in 2000s than in 1970s as a result of more
effective rainfall and less crop evapotranspiration.
a) 1971-1980 (b) 1981-1990 (c) 1991-2000 (d) 2001-2010
Figure 5: REIC by decade from 1971 to 2010.
(
3.2. Changes in water balance in the future
By the predictions of the SRES A1B scenario, annual mean rainfall will decrease in the
2040s compared with the 2000s, while a significant rise in annual mean temperature might
result in an increase in crop evapotranspiration. Fig. 6 shows increases of about 16.6% and
7.2% in AET and IR, respectively. As for the predicted REIC, the improved trend over the
past 40 years would reverse.
a) Rainfall (b) AET (c) IR (d) REIC
Figure 6: Water balance and REIC during the period from 2041 to 2050 under a climate
change scenario, A1B.
(
4. Summary and Discussion
This study proposes a cell-based simple water balance model for evaluating the irrigation
vulnerability of paddy fields. Several vulnerability indices such as CWSR, AWBR, and REIC
were designed to express changes in time and location. Simulation and statistics using
observed climate data showed that water balance in South Korea has improved over the last
four decades. Climate variation predicted by the SRES A1B scenario was also examined.
This study is on-going, and further work will be carried out as follows: a) the construction of a
cell-based runoff model, b) vulnerability assessment using RPC scenarios, c) the verification
of irrigation vulnerability indices, and d) modification for global-scale application.