Sustainable Adaptation Plan in Response to Climate Change and Population Growth in the Iraqi Part of Tigris River Basin
During the RP, the observed mean annual streamflow of UTW was 643.2 m3/s. Under RCP 2.6 (4.5), the streamflow tends to decline by 642.6, 642 and 639.4 (609.0, 594 and 582) m3/s for P1, P2 and P3, respectively. A greater decrease in mean annual streamflow is expected under RCP 8.5 with 602.6, 580.9 and 578.3 m3/s for P1, P2 and P3, respectively (Figure 2a). Figure 2b shows that the mean annual streamflow of GZW will decrease from 395.5 m3/s during the RP to 385.5, 377.7 and 376.3 m3/s under RCP 2.6 for P1, P2 and P3, respectively. Based on RCP 4.5 (RCP 8.5), the mean annual streamflow is expected to drop to 353.2, 347.4 and 343.4 (344.2, 337.5 and 327.8) m3/s for P1, P2 and P3, respectively. The future trend of the mean annual streamflow of DKW, shown in Figure 2c, was found to be 119.9, 115.4 and 115.2 m3/s under RCP 2.6 for P1, P2 and P3, respectively, compared with 122.6 m3/s during the RP. Whereas, under RCP 4.5 (RCP 8.5), a remarkable reduction in the mean annual streamflow with 110.7, 103.6 and 102.6 (103.4, 100.2 and 96.1) m3/s for P1, P2 and P3, respectively. For the DBW (Figure 2d), the mean annual streamflow during the RP was 19.8 m3/s, which will decrease for RCP 2.6 to 15.4, 15.2 and 14.4 m3/s during P1, P2 and P3, respectively. A greater decrease was found under RCP 4.5 (RCP 8.5) with 13.5, 13.0 and 12.3 (12.0, 11.4 and 10.2) m3/s for the three periods. The results in Figure 2e illustrated a reduced mean annual streamflow for ADW under RCP 2.6 (RCP 4.5) with 28.58, 28 and 27.86 m3/s (27.5, 26.6 and 25.5) for P1, P2 and P3, respectively, compared with 28.9 m3/s in the RP. In the warmest pathway, RCP 8.5, the mean annual streamflow was negatively impacted by climate change, with the decline reaching 24.8, 24.3 and 23.6 m3/s for P1, P2 and P3, respectively. For DRW, the observed mean annual streamflow was 160 m3/s in the RP. However, this magnitude will decline to 90.7, 83.7 and 82.1 m3/s under RCP 2.6 for P1, P2 and P3, respectively (Figure 2f). The projection under RCP 4.5 (RCP 8.5) showed a greater drop in mean annual streamflow, with 82.8, 70 and 69.7 (77.8, 67.9 and 56.6) m3/s, at the end of P1, P2 and P3, respectively. Figure 2g shows that the mean annual streamflow for HDW tends to reduce by 17.6, 17.25 and 17 m3/s under RCP 2.6 for P1, P2 and P3, respectively, while the observed mean annual streamflow was 44.7 m3/s in the RP. In the same context, a greater reduction will occur during P1, P2 and P3 under RCP 4.5 (RCP 8.5) with 14.34, 12.95 and 12.49 (12.73, 10.8 and 10.5) m3/s, respectively.
