p. 213-255 | Food security and water security in the Mediterranean are intrinsically linked and are facing similar challenges. Food security is threatened mainly by the high dependency of Mediterranean countries on food imports, making them vulnerable to external pressures such as volatile food prices. From a nutritional standpoint, the number of overweight and obese people has increased as a result of the traditional Mediterranean diet being abandoned. Water security has degenerated due to the deterioration of internal freshwater resources, both in terms of water quantity and quality, with a high dependency on external water resources, higher regional water footprints than the global average, increasing scarcity of renewable water resources, an increased number and capacity of dams exerting pressure on freshwater ecosystems, and a growing risk of conflicts between water users and countries. Access to water and sanitation remains a major challenge in the region. Territorial divisions separating coastal urban and remote rural areas are growing stronger, making isolated populations such as smallholder farmers particularly at risk of food and water insecurity. With climate change, precipitation is expected to decrease and temperatures to rise in the region, which will affect water supply (and thereby energy and food supply). It will also directly affect soil moisture and crop growth, thereby further increasing irrigation water needs. There are clear but difficult to measure interactions between the water, energy and agricultural sectors, as they are all interdependent, which calls for integrated policies and management. Agriculture being the largest water user in the region, further efforts need to be made to promote the use of non-conventional water resources. The conservation and restoration of Mediterranean agroecosystems is key to ensuring sustainable development. This requires better management of continuing arable land loss, land use intensification, and soil erosion and salinization. Integrated Water Resources Management and Water Demand Management (WDM) provide guidelines for achieving better water efficiency and reducing conflicts between users.

Water, food, energy, and the ecosystems they depend on interact with each other in highly complex and interlinked ways. These inter‐dependencies can be traced particularly well in the context of a river basin, which is delineated by hydrological boundaries. The interactions are shaped by humans interacting with nature and, as such, a river basin can be characterized as a complex, coupled socioecological system. The Niger River Basin in West Africa is such a system, where water infrastructure development to meet growing water, food, and energy demands may threaten a productive and vulnerable basin ecosystem. These dynamic interactions remain poorly understood. Trade‐off analyses between different sectors and at different spatial scales are needed to support solution‐oriented policy analysis, particularly in transboundary basins. This study assesses the impact of climate and human/anthropogenic changes on the water, energy, food, and ecosystem sectors and characterizes the resulting trade‐offs through a set of generic metrics related to the sustainability of water availability. Results suggest that dam development can mitigate negative impacts from climate change on hydropower generation and also on ecosystem health to some extent. | PR | IFPRI3; CRP5; ISI | EPTD | CGIAR Research Program on Water, Land and Ecosystems (WLE)

Water, food, energy, and the ecosystems they depend on interact with each other in highly complex and interlinked ways. These interdependencies can be traced particularly well in the context of a river basin, which is delineated by hydrological boundaries. The interactions are shaped by humans interacting with nature, and as such, a river basin can be characterized as a complex, coupled socioecological system. The Niger River Basin in West Africa is such a system, where water infrastructure development to meet growing water, food, and energy demands may threaten a productive and vulnerable basin ecosystem. These dynamic interactions remain poorly understood. Trade‐off analyses between different sectors and at different spatial scales are needed to support solution‐oriented policy analysis, particularly in transboundary basins. This study assesses the impact of climate and human/anthropogenic changes on the water, energy, food, and ecosystem sectors and characterizes the resulting trade‐offs through a set of generic metrics related to the sustainability of water availability. Results suggest that dam development can mitigate negative impacts from climate change on hydropower generation and also on ecosystem health to some extent.

To ensure water, energy and food supply security in the future, examining resources shortage risks within the integrated management strategy of the water-energy-food-society (WEFS) nexus system under uncertainties is necessary. Reliability, resilience, and vulnerability (RRV) are the most popular criteria for quantifying risks. However, their current applications focus on individual systems and adopt constant resource shortage rate thresholds across different spatial scales. To consider the interconnections in the WEFS nexus system and reflect the spatial heterogeneities of resource shortage risks when estimating the RRV, this study proposed a framework for estimating the RRV of the WEFS nexus system under uncertainties through a WEFS nexus model integrating water resources allocation model. Water availability uncertainty was simulated using Monte Carlo simulation and inputted into the stochastic WEFS nexus model. The water, energy, and food shortage rates outputted from the WEFS nexus model were used to determine the RRV of the WEFS nexus system. The impacts of water resources allocation on the RRV of the WEFS nexus system were studied by investigating its response to different water resources allocation scenarios at the basin and operational zone scales.