Precision Irrigation for Maximizing Water Use Productivity Under Diverse Climate Conditions Irrigation Water Requirements as Affected by Diverse Climate Conditions

Abstract

Determination of crop water requirement is one of the key parameters for precise irrigation scheduling, especially in regions with limited water resources, such as Egypt. Hence, an accurate estimation of reference evapotranspiration is very important especially in agriculture. The objectives of the present study were studying the influence of climate change on weather seasons and comparing
evapotranspiration estimations using Blany- Criddle and FAO-56 Penman-Monteith under present and future climatic conditions. Data of the present climate was collected from Wadi El-Natrun meteorological station, Egypt from 1991 to 2020. Meanwhile, the future climate data have been chosen for the concerned RCPs scenarios: RCP2.6, RCP4.5, RCP6.0 and RCP8.5 at 2040, 2060, 2080 and 2100.
The results revealed that all month’s reordered T mean above 20 oC, except December, January and February where they ranged between 17.68 and 19.44 oC. The highest T mean was observed at July (32.3oC), August (31.9 oC), and June (31.8 oC), while February scored the lowest T mean (17.7 oC). Data indicated that estimated ETo by BC was more than PM under all months and rate of increase was small under summer season (7.9, 4.9, 6.3), while the highest increase % was observed under cold months: November (51.4), December (73.1), January (79.5) and February (48.3). Respecting the total ETo estimated by BC and PM were2056 and 1694 mm/year, respectively, which indicated that BC was higher than PM by about 21.4%. It is clear that scenario (2.6) showed more harmony for the future than (8.5) scenario. With respect to the highest change the percentage of increase of 2.6, 4.5, 6, and 8.5 as compared 2100 with control 2020 were 3.1, 7.5, 10.1, and 18.4 % respectively. Estimated ETo by BC at 2.6 scenario was homogeneity while the opposite was true at 8.5 scenario. The same trend was observed at ETo estimated by PM. Compared between BC and PMs ETo at 2.6 and 8.5 scenarios (Fig. 7), data pointed out that the minimum ETo values estimated by BC and PM equations were 103.36 (February), 208.76 (July) and 48.45, 187.31 mm/month after 2.6 scenario and 107.13, 215.52 mm and 53.18, 198.83 mm after 8.5 scenario in same sequence. Also, data cleared that the total ETo (from May to September) after BC and PM were 968.30, 841.10 and 998.25, 887.81 mm after 2.6 and 8.5 Scenarios respectively, with an increase of 3.1 and 5.6 % comparing BC and PM at Scenario 8.5 with 2.6.