With increasing urbanization the pressure on ESS and resources in peri-urban areas is also increasing: 1) there is significant competition for land and water, resulting often e.g. in informal water markets, 2) the city is releasing waste and wastewater causing pollution in the peri-urban areas and 3) there is inefficient nutrient application and poor coupling of (peri-)urban crop and livestock production which often causes negative externalities in UPA systems of African cities threatening human health and groundwater quality. This project looks at opportunities and constraints of urban food security and urban and peri-urban farming in Ghana, Sri Lanka and Burkina Faso focusing among others at rural-urban nutrient flows. The following sub-components are considered: a) mapping rural-urban food flows, b) land use changes with increasing urbanization, b) valuing changes in ESS from an economic perspective, and c) analyzing options to improve urban farming systems, wastewater use and rural-urban nutrient flows. A particular component of the project is capacity building through the involvement of several PhD students.