Water requirements for the clover and cotton crops under both current climate and climate change conditions in 2040 was calculated using Basic Irrigation Scheduling (BISm) model. Hargreaves-Samani equation is used to calculate ETo in case of only temperature data are input. ECHAM5 model (Roeckner et al. 2003) was used to develop A1B climate change scenario for each weather station in each governorate in 2040. The herein results indicated that climate change condition in 2040 is expected to increase ET values for all Egyptian Governorates and consequently crop water requirements will follow similar trend. Crop water requirements for the crops grown at Middle and Upper Egypt will be higher than those cultivated at Lower Egypt. Under climate change conditions, great competition on the limited water resources between economic sectors will be raised and agricultural activity is the most negatively affected sector.. The most important results could be as follows:-
1- Under climate change conditions the yearly ETo value is expected to increase by 8% in the Nile Delta for governorates that has a shore on Mediterranean Sea i.e. Alexandria, El-Behira, Kafr El-Sheik, El-Dakahlia and Demiatt. In the rest of Nile Delta Governorates, the percentage of increase was 9%. In Middle Egypt, the increase percentage reached to 11%. Furthermore, in Upper Egypt the increase percentage was between 11and 18%, where the highest increase percentage was 18% in Aswan.
2- The difference between ET under current climate and under climate change during clover growing season was low (4-5%). Starting from El-Gharbia governorate, the difference became higher (10%) and highest difference was found in Aswan which reached 15%.
3- The applied irrigation water for cotton under climate change conditions were higher than those under current climate conditions by 6 to 8% in the Nile Delta, 9% in Middle Egypt and 10-12% in Upper Egypt.
Based on the above results and to mitigate such problem, irrigation practices, in particular surface irrigation methods, must be change to be more effective to save irrigation water without significant reduction in output yields. The saved water could be oriented for establishing new agricultural societies in the newly reclaimed lands. In addition, it is very important to improve the production system via cultivated high – yielding crop varieties, proper sowing dates and applying suitable irrigation and fertilization management will be helpful in this respect.