Small Reservoirs in Africa: A Review and Synthesis to Strengthen Future Investment.

Background Small reservoirs are a critical mechanism to strengthen resilience and enhance rural livelihoods in Africa. They provide a range of benefits, including increased access to water in local communities, improved household food security, diversified livelihood options, female empowerment and enhanced entrepreneurial activities. As a result, governments, development agencies and the private sector have invested significant resources in constructing new or rehabilitating existing small reservoirs. However, a range of factors, including insufficient maintenance, rapid siltation and ineffective institutions, can weaken the performance of small reservoirs. Reconciling mixed evidence to generate a balanced picture - Despite existing data on various benefits and costs of small reservoirs in Africa, no comprehensive assessment of their impacts has been undertaken. Case studies yield important insights, but cannot be used individually to confidently generalize. This paper responds to the lack of comprehensive examination of the impacts of small reservoirs by undertaking a stock-take of available evidence to understand the frequency of reporting of various impacts, benefits and costs. A survey of available evidence provides the basis for more conclusive guidance on how to improve the performance of small reservoirs in Africa. Objectives and methods - This paper synthesizes available literature on the benefits, performance and challenges of small reservoirs, and provides recommendations that can inform future investment. The study compiled and classified more than 80 documents concerning about 4,000 small reservoirs in Africa, according to a set of basic, descriptive and explanatory parameters. Basic parameters describe a reservoir's name, location and investment status. Descriptive parameters capture the impacts of a reservoir (what happened) and explanatory parameters capture the determinants of the impact (why it happened). In addition, the study included field-based research on the conditions around a set of 10 small reservoirs in southern Zambia, which enabled more nuanced analysis and discussion of key findings. Field-based data were collected through conducting interviews on a set of key parameters including benefits, costs, degree of functionality, institutions and maintenance. Results from document analysis - Results from the desktop study show a range of benefits derived from small reservoirs. These benefits include improved reliability of access to domestic water and expanded irrigation water supply, as well as increased livestock watering and greater entrepreneurial activities. Further, positive impacts realized include improved household food security, increased household income, reduced out-migration and the empowerment of women. Identified costs were relatively fewer than benefits. Costs were limited to conflicts in communities on water and land use, membership fees for users, and negative health impacts arising from water-related diseases. The performance of small reservoirs is generally rated as mixed to poor. Operational lifespans of less than 10 years, and high water loss rates in small reservoirs illustrate this poor performance. Reasons for the poor performance include weak institutions, sedimentation, poor siting and inadequate maintenance. Results from fieldwork - The case study based on fieldwork in southern Zambia confirmed both the benefits and challenges of small reservoirs that emerged from the document analysis. Further, fieldwork identified that the short-term planning horizon for investments in small reservoirs, often driven by emergency response, contributes to a rapid decline in the functionality of small reservoir infrastructure, the primary factor for such an outcome being sedimentation. However, the advocacyoriented nature of investments in small reservoirs may create a positive narrative that eclipses their generally poor performance. More significantly, fieldwork provided evidence that suggests that reinvesting in old infrastructure might be more cost-effective than building a new reservoir, particularly since the structural quality of new small dams seems to be declining. Key messages - The results point to five key messages. First, small reservoirs produce a range of benefits that provide practical value to rural communities. Second, the performance of small reservoirs - measured through economic analysis, reservoir longevity or other means - is generally not spectacular. Third, the primary factor explaining the temporal decrease in reservoir lifespan is sedimentation - explained by a host of factors, including institutions. Fourth, rehabilitation appears to be a better investment than new dam construction. Fifth, the quality of small dam infrastructure may be declining. Conclusions - Ultimately, findings from this study suggest that rehabilitating existing reservoirs may be more efficient than building new infrastructure to gain the benefits of small reservoirs. At the same time, findings also point to broader lessons on the need to change the approach to small reservoir development and management. In other words, to consider adopting a long-term, more holistic approach (or model) to the construction and maintenance of small reservoirs that match the challenges associated with sustainably tapping the benefits of the water that they store. The following three points are worth mentioning in this regard: • It is time to adapt the design of advocacy-based, disaster-responsive investments in small reservoirs, by drawing more evidence-based, practically informed approaches. In practice, this may mean insistence on the achievement of certain benchmarks by local institutions, such as provision for the collection and management of recurring costs of controlling sedimentation. • The long-term approach needed for investments in sustainable small reservoirs will require formal institutions, presumably national small reservoir programs, to ensure sustainability by managing and maintaining infrastructure. • Regular monitoring of reservoirs after investment is critical to the success of a long-term approach to investments in small reservoirs. [ABSTRACT FROM AUTHOR]