It then describes the main bottlenecks that can be envisaged as they relate to water use, land use and energy use, as well as the materials dimension of the nexus. Finally, it motivates why an integrated dynamic modelling approach is most suitable for investigating the interlinkages of the nexus bottlenecks. We need water to grow food and for energy production, we need energy to grow' food and to pump and treat water, and w,e need land to produce bioenergy. Unsustainable use of these resources raises serious concerns about their looming scarcity.