Exploring water fluxes for agricultural production in African croplands

The deteriorating status of water scarcity and food insecurity poses a global challenge, driven by population growth, rapid urbanization, socio-economic developments, shifting consumption patterns, inefficient resource use, and climate change impacts. Agriculture, the largest user of freshwater and land resources, faces constraints due to diminishing availability of both blue and green water resources, leading to food shortages and increased vulnerabilities, particularly in Africa’s developing regions. Recent trends in Africa show expansions in both rainfed and irrigated croplands. However, agricultural extensification strategies can disrupt ecosystems and biodiversity, notably in targeted floodplain wetlands, and exacerbate competition for scarce blue water resources, especially in arid regions and transboundary river basins. This thesis underscores the pressing need for agricultural intensification, emphasizing the enhancement of productivity on existing croplands. The aim of this research is to identify and quantify the potential for increasing crop yields while conserving water and land resources across diverse agricultural systems in Egypt, Sudan, Ethiopia, and Tanzania. Additionally, this research aims to provide insights into the implications of potential improvements for future crop intensification and the associated demand for water and land resources. To achieve these multidisciplinary aims in such data-scarce regions, this research has developed novel methodological approaches. These approaches integrate open-access remote sensing datasets and secondary data to accurately monitor agricultural systems and associated parameters including land use, land cover, precipitation, actual and potential evapotranspiration, crop yield, and crop transpiration. This thesis has demonstrated how these transferrable methodological approaches offer in-depth insights into the performance of agricultural systems, by calculating performance indicators including water use efficiency, crop water productivity, land productivity, evaporative stress, relative evaporative stress, and transpiration fraction, at adequate spatial and temporal resolutions across regions of diverse agricultural types, scales, and challenges. The spatial-temporal investigation conducted, covering sufficient timespans and spatial extents, proved instrumental in detecting spatial and temporal variabilities in performance indicators, thus enabling a reliable understanding of current performance status and facilitating the detection and quantification of potential improvements. These identified improvements have been used to construct plausible scenarios of future crop intensification and associated water and land requirements. Furthermore, the analyses conducted have identified specific interventions necessary to enhance production efficiency and to conserve water and land resources across the studied regions. The findings of this thesis emphasize the considerable potential for crop intensification in the studied regions. The identified improvements have profound implications for water and food securities as well as for the sustainable development of water and land resources. These findings serve as pivotal entry points for guiding interventions and investments to enhance crop production and conserving vital water and land resources. These insights are valuable for strategic decision-making, directing efforts towards fostering agricultural sustainability and resilience amidst evolving environmental and socio-economic challenges

Will the Eastern Nile countries be able to sustain their crop production by 2050? An outlook from water and land perspectives

Securing agricultural commodities for a growing population requires a paradigm shift in agricultural thinking. An appropriate agricultural development pathway should be determined, which may include larger land extensions and water consumption or more intensive use of smaller extensions and optimized water use. This study ad-dresses this question in the Eastern Nile Basin countries (ENC), namely Egypt, Sudan, and Ethiopia, where such research is scarce. We utilized open-source datasets, based on relevant remote sensing products and agricultural statistics (harvested area, production, yield, and water footprint [WFP]), to understand the spatio-temporal var-iability of cropland performance. The study proposes a scenario-based approach that evaluates four development pathways towards sufficient crop production by 2050 in the ENC. While the extensification pathway suggests a continuation of the business-as-usual, i.e., same average WFP and yield values (horizontal scenario), three inten-sification pathways assume that increased efficiency can improve WFP and yield values (vertical scenarios). Re-sults show that substantial amounts of water and land could be saved by 2050 by following the vertical development pathways. Nonetheless, the three countries, especially Egypt, are expected to face enormous chal-lenges to satisfy their future demand for the main crops by 2050. Our research provides key messages to promote cooperation between the three countries by following a regional benefit-sharing approach to the challenge. The findings of the current study have deep implications on sustainable natural resources development and water and food security in such a vital and conflicted region. (C)2021 Elsevier B.V. All rights reserved

The Performance of Satellite-Based Actual Evapotranspiration Products and the Assessment of Irrigation Efficiency in Egypt

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