Sustainability in the Food-Water-Ecosystem Nexus: The Role of Land Use and Land Cover Change for Water Resources and Ecosystems in the Kilombero Wetland, Tanzania  
Belgian and European aid and executed by the Tanzanian Ministry of Natural Resources and Tourism and the Belgian Development Agency. All three projects focus on the sustainable use and management of wetland ecosystems and the use of satellite-based maps and products. This collaboration directly contributes to the GEO-Wetlands initiative that was recently established as part of the 2017-2019 Work Programme of the Group on Earth Observations (GEO) through a partnership led by several SWOS partners together with the Ramsar Convention Secretariat, the European Space Agency and others. Globally, wetlands are one of the most endangered and fastest declining ecosystems, but there are few spatially inclusive and comprehensive quantitative studies on global wetland degradation and loss [1; 2; 3; 4]. Several global conventions and Multilateral Environmental Agreements therefore strive for their protection and sustainable use and require high quality data and information about their status and trends [5; 6]. Understanding wetland hydrology at multiple scales is crucial to assess the impact of on-site and off-site water resources management measures on diverse wetland ecosystem services. This implies the analysis of catchment-wetland interactions to determine altered wetland water inflows based on local climate variability and land use changes of the upstream catchment and furthermore the impact of wetland use on downstream riparian [7]. Applying historic land-use data, [PERSON] et al. (2007) [8] have demonstrated on a global scale that land-use change has an overall significant impact on hydrological runoff regimes. Furthermore, they have shown that land-use change has had the strongest impact in tropical regions with an even higher share than expected of climate change. Therefore, Integrated Water Resources Management will only provide sustainable solutions with a focus on the complete green-blue water approach [9]. With the growing water demand, especially from agricultural activities, there is an accumulative risk that additional water demands of various sectors cannot be satisfied during the hydrological cycle of the year [10]. The 2030 agenda framed 17 sustainable development goals (SDGs) including a total of 169 targets highlighting the key role of climate and natural resources like water, soil and ecosystems providing the basis for sustainable development. There is a strong need to balance the tradeoffs between the different SDGs and the related targets [11; 12]. Water is one of the key links between the SDGs as an integral part of human development and ecosystem needs [13]. With respect to the food-water-energy nexus, [PERSON] et al. (2015) [14] postulate an urgent need in solution-oriented integrated research on land, water and energy efficiency which is indeed also essential for the sustainability in the food-water-ecosystem nexus under the framework of the different SDGs and their related targets. Overall estimates of increased future water use in sub-Saharan Africa (SSA) primarily concentrate on the energy (hydropower) and agricultural sector [15]. Focusing on the sustainability assessment of the food-water-ecosystem nexus for wetland ecosystems, it is essential to apply an integrated catchment-wetland approach to identify the impact of land use changes on the catchments and the wetlands' water budget in particular and hence on the water-related ecosystem services, again regulating ecosystem health and agricultural practice. There are numerous recent hydrological grid-based model developments and applications assessing the impact of global change, including Land Use Land Cover Change (LULCC), on the water resources at various scales [16; 17; 18; 19].