Long- Term Estimation of Actual Crop Evapotranspiration Based on Satellite Data Analysis

Abstract

Abstract Arid regions conditions are overwhelmed with various water scarcities problems, however, one of the reasons of this problems may be due to climate change effect. Moreover, under these conditions, water is a crucial key for any agricultural development processes. Therefore, the aim of this study was to estimate the actual evapotranspiration of different crop pattern under climate change conditions based on satellite data analysis for long time effect (1985 – 2019). The study area is considered active agricultural area , the percentage of bare soil and vegetation cover were (86.9%) and (12.7) in 1985 while in 2019 the percentage of bare soil sharply decrease so it was reached to (34.1%) but the percentage of d vegetation cover was (64.2%). Satellite images have been gathered and analyzed from Landsat TM, Landsat ETM+ and Landsat OLI, through the studied period. However, Normalized Difference Vegetation Index (NDVI) had been obtained for estimating the actual evapotranspiration under the studied area conditions. Planning and management of water use by irrigation agriculture are especially important in an arid and semiarid areas like the study area so the understanding of the Actual Evapotranspiration (AET) prerequisite for better management and conservation of agriculture water, By determine the area of every crop pattern, actual evapotranspiration (AET) was estimated by m3/ha/day and m3/total cultivated area/day. Data analysis indicate that the minimum and maximum NDVI values had been ranged from 0.7 and 0.9 for mango trees from 1985 and 2019, 0.5 and 0.8 for olive trees, 0.4 and 0.8 for forests and 0.7 for annual crops within the studied period from 1985 to 2019. The minimum and maximum actual evapotranspiration under different crop pattern from 1985 to 2019 ranged from 2.6 and 4.9 mm/day, 1.7 and 4 mm/day, 1 to 4.4 mm/day and 2.7 mm/day for the same crop pattern respectively. This study can assist in water management practices for better irrigation management.