Abstract
Monitoring of crop water consumption, also known as actual evapotranspiration (ETa), is crucial for the prudent use of limited freshwater resources. Remote-sensing-based algorithms have become a popular approach for providing spatio-temporal information on ETa. Satellite-based ETa products are widely available. However, identifying an adequate product remains a challenge due to validation data scarcity. This study developed an assessment process to identify superior ETa products in agricultural areas in Egypt. The land cover product (MCD12Q1) from Moderate Resolution Imaging Spectroradiometer (MODIS) was evaluated and used to detect agricultural areas. The performances of three ETa products, namely: Earth Engine Evapotranspiration Flux (EEFlux), USGS-FEWS NET SSEBop ETa monthly product, and MODIS ETa monthly product (MOD16A2), were evaluated. The ETa values of these products were compared to previous ETa observations and evaluated using the integrated Normalized Difference Vegetation Index (iNDVI) on a seasonal and annual basis. Finally, the irrigation efficiency throughout Egypt was calculated based on the annual Relative Water Supply (RWS) index. Results reveal that the SSEBop monthly product has the best performance in Egypt, followed by the MOD16A2. The EEFlux overestimated ETa values by 36%. RWS had a range of 0.96–1.47, indicating high irrigation efficiency. The findings reported herein can assist in improving irrigation water management in Egypt and the Nile Basin.
Highlights
70% of all global freshwater use is consumed by irrigated agriculture [1,2,3,4]
The ETa values of these products were compared to previous ETa observations and evaluated using the integrated Normalized Difference Vegetation Index on a seasonal and annual basis
The findings reported can assist in improving irrigation water management in Egypt and the Nile Basin
Summary
70% of all global freshwater use is consumed by irrigated agriculture [1,2,3,4]. Water scarcity has become a limiting factor for agricultural production, especially in arid and semi-arid regions, where crop water consumption exceeds precipitation. These regions rely on water extracted from surface and/or groundwater sources to compensate for irrigation water deficits. Egypt is the most downstream nation in the Nile Basin, and most of its freshwater inflow (≈97%) comes from outside its boundaries [7,8]. Omar and Moussa [9] claimed that the water shortage for different sectors in Egypt equaled to 13.5 Billion cubic meters (BCM) per year and expected this deficit to increase continuously
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