Exploring water fluxes for agricultural production in African croplands

Abstract

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. <br /> 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. <br /> 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. <br /> 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.