Evaluation of wheat and Sugar beet water use Variation due to Climate Change Effects in two Coming Decades in the Selected plains of Khorasan Razavi Province

One of the main consequences of climate change is its impact on agricultural water use that could face the water resources management with serious challenges. In this research, to examine climate change influence on sugar beet and wheat water use in selected plains of Khorasan Razavi province, minimum temperature, maximum temperature, precipitation and sunshine hours for 2 coming decades were simulated using LARS-WG5 model according A1B, A2 and B1 scenarios confirmed by IPCC. Then potential and actual evapotranspiration and effective rainfall calculated using Hargreaves-Samani and FAO methods respectively and were determinate water requirements of these plants on the next 20 years compared with the base period (1991-2010). The results showed that the minimum and maximum temperatures will increase at all selected plains and the highest increase in minimum temperature in wheat growing period under all three scenarios A1B, A2 and B1 respectively equal 30.9, 45.77 and 29.13 percent will be seen in Sabzevar and during growth period of sugar beet respectively above scenarios will be seen in Golmakan with 5.23, Neyshabur with 6.62 and Neyshabur with 4.77. Also precipitation will increase in all stations except Torbat jam and the highest rate of increase in wheat growing period under these scenarios, respectively 35.24, 35.56 and 42.49 percent will be seen in Gonabad and in sugar beet growing period, respectively 69.21, 80.95 and 70.19 will occur in Sabzevar, Gonabad and Sarakhs. The results also showed that the water requirement of these plants in most plains of province will not noticeably change except of Torbat jam-Fariman that will increase equal 17, 14 and 18 percent in the growth period of wheat and 19, 18 and 18 percent in growth period of sugar beet and Sarakhs that will faced with reducing equal 14, 15 and 15 percent in the growth period of wheat and 6 percent in the growth period of sugar beet according the above scenarios.