Ahmed Helmy El-Sayed1*, Magdy Hassan Mowafey 2, and Maha Rashad Fahmy3
Abstract—High percent of the Arab countries suffer from great shortage in their water resources because it lies in hot arid and semiarid regions. However, vast areas of these regions are utilized for agricultural production, which require making essential studies regarding the determination of water requirements for irrigation purposes, i.e. determination of crops’ consumptive use of water in such areas. Crops’ consumptive use of water is related to evapo-transpiration by a coefficient called crop coefficient, which depends on type of crop and its growing stage. In addition, evaporation measurements are of great importance for irrigation systems design, irrigation rotations, and development of hydrologic models. In the present research, a seasonal regression-autoregressive “S(REG_AR)” model has been developed and used to simulate and estimate monthly evapo-transpiration, and hence water requirements for agricultural crops in Al-Sharqia governorate, which is one of the major provinces in Egypt. Actually, the present research is a part of a two-year research project, which has been planned and funded by Zagazig University, Egypt. The performance of the developed model has been evaluated by calculating the statistical characteristics of both the estimated and measured values of monthly evapo-transpiration in each of the historical and validation periods. Analysis of results revealed the adequacy of the developed model and hence its capability of doing good estimation of monthly evapo-transpiration in Al-Sharqia governorate and in regions of similar climatic conditions.
Index Terms— Blaney - Criddle, Consumptive use of water, Dummy variables, Evapo-transpiration, Penman, “S(REG_AR)” model, Thornthwaite, Turc.
In the present time, the study of water resources
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