# Climate-Smart Agro-Hydroological Model for a Large Scale Rice Irrigation Scheme in Malaysia
## 3 Results and Discussion
### Water Demand Projection  
The projected water demand during the dry season under multi-model projections based on RCP4.5, 6.0, and 8.5 scenarios suggests an increasing pattern in water demand, with a higher increase (11.09%) expected under the RCP8.5 scenario in the latter part of the century (2080s), except for RCP6.0, under which a decreased pattern is predicted in some years (Table 5 and Figure 9). The average changes in this season are 5.59%, \(-\)5.75%, and 10.71% for RCPs 4.5, 6.0, and 8.5, respectively. The model outputs reveal that the water demand increment in the dry season is due to the increase in temperature and decrease in rainfall during the season. During the wet season, water demand is projected to decrease 2.6% (6.2%) in all three future periods for RCP 4.5 (RCP 8.5) scenarios. However, RCP 6.0 predicts an increase of about 9.0% in the same season. Although temperature is projected to increase in the \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Irrigation Season**} & \multicolumn{2}{c}{**Period**} & \multicolumn{2}{c}{**Changes (\%) in Streamflow**} \\ \cline{2-5}  & & **RCP4.5** & **RCP6.0** & **RCP8.5** \\ \hline \multirow{3}{*}{Dry Season} & 2020s & \(-\)0.40 & \(-\)1.70 & \(-\)5.66 \\  & 2050s & \(-\)0.63 & \(-\)1.90 & \(-\)5.54 \\  & 2080s & \(-\)0.18 & \(-\)1.44 & \(-\)5.94 \\  & Average & \(-\)0.40 & \(-\)1.68 & \(-\)5.71 \\ \hline \multirow{3}{*}{Wet Season} & 2020s & 0.19 & \(-\)0.84 & \(-\)3.92 \\  & 2050s & 0.59 & \(-\)0.47 & \(-\)3.67 \\ \cline{1-1}  & 2080s & 0.31 & \(-\)0.71 & \(-\)3.90 \\ \cline{1-1}  & Average & 0.36 & \(-\)0.67 & \(-\)3.83 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Projected changes in streamflow under multi-model projections based on RCP scenarios relative to the baseline period of 1976–2005. Figure 8: Projected mean monthly available supply from multiple models for three RCP scenarios (RCPs 4.5, 6.0, and 8.5) for three future periods of 2010–2039, 2040–2069, and 2070–2099 relative to the baseline period of 1976–2005. wet season, the reason for the decrease in the water demand in the season, as revealed by the model, is due to a significant contribution from the effective rainfall following the Northeast Monsoon rainfall during the wet season, which compensates for the warmer periods. [PERSON] et al. [46] also reported that climate change may not significantly affect water availability in the countries of South-East Asia because water demand will decrease due to increased rainfall. However, in both seasons the RCP6.0 scenario shows different change patterns. This might be due to the lack of data available for this scenario in some GCM repositories (Table 2). Therefore, the RCP 6.0 scenario should only be used with extreme care in the future implementation of the developed model. The model outputs also indicate the scheme will require more irrigation water in the future (with a higher rate under RCP8.5) in the months of March and September during dry and wet seasons, respectively. This is because in March (during the dry season), ISA III requires pre-saturation plus normal irrigations for ISAs I, II, and III, which require larger irrigation amounts. In addition, in September (during the wet season), ISA III is pre-saturated together with ISAs I, II, and III under normal irrigations. On the other hand, less water demand is observed from May to June in the dry season period and from November to December in the wet season. Normal irrigations are only observed in these periods, which require lesser irrigation amount. The water demand in the scheme will differ greatly over the months of the dry season in the future, and the increase in effective rainfall