In semi-arid areas of Tanzania vulnerability context is depicted as the starting component for policy process analysis through the sustainable livelihood approach. Giving vulnerability a high prominence in this analysis allowed the research to consider all kinds of vulnerabilities as central issues to the ways in which livelihoods are shaped. Hence the Sustainable Livelihood framework was used in this research as the comprehensive framework for assessing the contributing factors to limited water resources availability to sustain people’s livelihoods. The study revealed that, changes in the quantity, timing, intensity and duration of rainfall as a result of climate change contributes to greater water stress and making people more vulnerable. Due to over-abstraction upstream of the Great Ruaha River, it implies that, people depending on the water resources downstream of the Great Ruaha River catchment are vulnerable. Their livelihoods are at risks as they don’t have water for irrigation and other economic activities. The study also revealed that, both vulnerability and livelihood strategies are derived through natural water availability which features droughts, climate change and the link between water availability, agricultural production, and outcomes.