This “Volume 4 – Environmental flows assessment” is the 4th and last of a 4-part series and a supplementary volume to the Sudd Monograph, a key output of the NBI’s Wetlands Programme support to South Sudan through the South Sudan's Wetlands Working Group, which aims to develop a comprehensive information and knowledge base on the existing conditions of the Sudd that can be used as an aid by decision makers to help guide future planning and development initiatives. Supplementary volumes follow with specific focus on detail aspects such as hydrological modelling, TEEB and environmental flows. These documents will be important sources from which to reference critical information that is required to ensure sound management of the Sudd.