Ecosystems (e.g. forests, wetlands and grasslands) and the environment are critical components of the global water cycle. All freshwater ultimately depends on the continued healthy functioning of ecosystems and the broader environment and recognising the water cycle as a biophysical process is essential to achieving sustainable water management. Biodiversity within inland water ecosystems is both highly diverse and of great regional importance to livelihoods and economies. However, development activities are not always cognisant with the conservation of this diversity and it is poorly represented within the development planning process.

All countries in Eastern and Southern Africa now increasingly realise that greater investments are needed to protect aquatic ecosystems and the environment from the negative impact of human developments. On the other hand, implementation of the polluter pays principle is either very slow or non-existent. Integration of ecosystem needs into water management practices empowers decision makers to engage major productive water users with the clear end goal of sustainability. Addressing the challenge of striking the right balance between allocating water for direct human use (agriculture, power generation, domestic purposes and industry) and indirect use (sustenance of ecosystem goods and services) in view of global challenges such as urbanisation and climate change become less subjective. Improved understanding of the linkages between the various water sources and uses, which implies recognising the existence of, not just hydrological boundaries, but ecosystems boundaries both at the national and transboundary levels is critical. 

The papers in this sub-theme address new and innovative methodologies for determining environmental water requirements, recent advances and best practices in environmental impact assessment, valuation of ecosystems services and goods, determining ecosystems boundaries, inclusion of ecosystem goods and services in water resources development, pollution prevention and treatment and river basin management, wise use of water-linked ecosystems and people's livelihoods, as well as studies of water quality in the IWRM framework.