Water competition, variability and river basin governance: a critical analysis of the Great Ruaha River, Tanzania

This chapter analyses historical irrigation and river basin developments and narratives to demonstrate particular dimensions of water competition in the Great Ruaha River basin in southern Tanzania. Alongside this, we identify three interrelated scalar and emergent dynamic behaviours revealed as a part of basin development. These ‘systems’ behaviours relate to the growth and coalescing of areas of smallholder irrigated farms since the late 1950s. The three concepts are termed ‘parageoplasia’,1 ‘non equilibrium behaviour’ and ‘share modification’. These insights provide additional layers to the ideas captured in Molle’s (2003) conceptual framework for river basin development, specifically on the demand–supply equation, where we bring additional thinking to his allocation ‘third way’ and on the nature of basin development. While exploring the broad narrative of growth in water demand, we explore further dimensions arising from a highly variable inter-/intra-annual water availability, which affects the distribution of water and impacts of this growth curve, as informed by a sub-Saharan environment. As well as explaining the concepts terms, we argue that the ideas revealed by this case study might have application to smallholder irrigation elsewhere in savannah agro-ecologies in Africa. The chapter explores how this analysis leads to new insights – particularly in relation to adaptation to climatic change expressed through increased variability of rain fall and river flow (Milly et al., 2008).