PhD Abstract

This thesis addresses a fundamental lack of critical research investigating the meaning and practical application of widely used water scarcity metrics that include the Falkenmark Water Stress Index (WSI) and the Water Withdrawal to Availability (WTA) ratio. Recognising that current indicators do not account for the significant inter- and intra-annual variability in freshwater resources, this research proposes a new methodology to characterise water scarcity that explicitly considers the contribution of water storage to freshwater availability. This approach also specifically addresses common assumptions of domestic water demands (i.e. ~100 litres capita day (LCPD)) and adaptive strategies that people employ to maintain access to freshwater.
Central to the arguments presented in this thesis is a case-study from the semi-arid Great Ruaha River Catchment (GRRC) in Tanzania. Application of the two metrics to the GRRC provide contrasting results, despite an absence of river discharge for an increasing period of the year. Investigating the strong inter-annual variability of freshwater availability suggests that naturally-occurring shifts in upstream hydrology may have a greater impact on downstream zero-flows than previously suggested, bringing into question the predominant narrative that livestock keepers and irrigation has constituted the primary cause for the experienced water shortages.
Fieldwork, informed by a mixed-methods approach, quantifies domestic water demand in three villages to show that domestic water use is significantly lower than the assumed ~100 LCPD embedded in the WSI. Analysing the pathways to accessing the varying water available in the same villages show that development interventions which did not follow participatory approaches, failed. As a response to the resulting lack of clarity over water infrastructure ownership, informal pathways emerge through self-supply water storage systems such as hand-dug wells. Such systems are not uncommon in sub-Saharan Africa but remain inadequately represented in water scarcity metrics.
Finally, the research applies a novel framework with which to characterise water scarcity by inter-and intra-annual contributions of storage to water availability, portraying that despite a progressively increasing magnitude and periodicity of water scarcity throughout the dry season, the contributions of freshwater storage can act as a resilient buffer to reduce intra-annual scarcity in the GRRC by two to three months. The impact of an indicator informed by storage is significant as it allows for formal incorporation and measurement of common but neglected methods of adaptation to water shortages.

Citzen Science & Water