Review of Agricultural Water Management Intervention Impacts at the Watershed Scale: a Synthesis Using the Sustainable Livelihoods Framework

Agricultural water management (AWM) interventions are increasingly being promoted as a first step to enable further investments for necessary productivity gains and yield increases in the smallholder farming systems that dominate rural sub-Sahara Africa and South Asia.

These AWMs range from in-situ soil and water management improvements (conservation tillage, terraces, pitting) to supplemental and full irrigation systems, drawing water from a wide variety of sources in the landscape. However, re-allocation of water, i.e. changing the spatial and/or temporal flow of water in the landscape, can potentially undermine other uses of the same water, for other livelihood purposes or, indirectly, by reducing availability for support of different ecosystem services (Batchelor et al, 2002; Shiferaw et al., 2008). In extreme cases, these changes can cause so-called shifts in resource availability, which may not be possible to restore. These changes toward undesirable productivity states have been described elsewhere as undermining social-ecological resilience (cf Gordon et al, 2008).

To date, there is little synthesised knowledge regarding how much AWM interventions can improve livelihoods in poverty-dominated rural areas in sub-Sahara Africa and South Asia. Despite the growing number of examples of significant changes in landscape water flows (notably reduced groundwater tables and decreased water quality due to agricultural intensification), thus far little attention has been given to the environmental impacts AWM interventions may have. In addition, despite a growing number of success stories, there is evidence that the impacts of AWM interventions are often evaluated in a one-dimensional way, either from a natural resource or social-human perspective. Much evidence is still based on a limited number of meta-analyses that in themselves point to inconclusive outcomes due to inconsistent or sometimes nonexistent monitoring and evaluation of impacts (World Bank, 2007; Joshi et al, 2008; Barron et al, 2008; Kerr, 2002; Joshi et al, 2005)

This synthesis focuses on capturing the changes in different capitals that AWM interventions may have at the watershed scale (i.e., at meso-scale, 1- 10 000 km2). The aim is to assess which impacts are predominant, and if these relate to negative or positive impacts. Secondly, this review will suggest parameters needed for inclusion in monitoring and evaluation of AWM interventions in the project pilot watershed areas. These parameters will assist in addressing potential positive and/or negative impacts of AWM from a holistic socialenvironmental perspective at the landscape scale. These outcomes could further be used to guide potential cost and/or benefit estimates of AWM interventions.

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