Sri Lanka has one of the oldest traditions of irrigation in the world, dating back as far back as 500 BC. It was around these ancient tank (water storage reservoir) irrigation systems that the economy and human settlements of early Sri Lankan society were organised into a “hydraulic civilization”. Unlike in the case of most ancient civilizations, which grew in fertile river valleys and floodwater retention areas, Sri Lankan hydraulic societies were based on reservoir systems.
Traditional tank systems thus form a vital component of both the natural and man-made landscape in Sri Lanka. Providing irrigation water, domestic supplies and natural resources to millions of people, they also constitute one of the richest sources of wetland biodiversity in the country. Yet traditional tank systems are also under severe, and increasing, threat – which is, in turn, both putting in danger livelihood security and threatening the status of biodiversity. These threats arise from multiple sources, including upstream water allocation decisions, which marginalise traditional tank systems in favor of seemingly more productive uses such as “modern” large-scale irrigation and hydropower, as well as from siltation and sedimentation arising from unsustainable land use practices in upper catchments. The reduced capacity of the reservoirs will result in less irrigation water available for downstream lands and livelihood benefits to the community.
The study quantifies the benefits associated with tank goods and services, and underlines their high economic and livelihood value to local communities. It also looks at the economic returns to different options for restoring and maintaining the traditional tank system. These results reveal that removing silt and rehabilitation of tank reservation is the most feasible option, which could improve the services, provided for a longer period of time and give the highest economic return.
The study concludes by making recommendations about economic and financial instruments to strengthen tank management. Although the government spends lot of resources to maintain the tanks, the communities around the tanks are not happy and complain about the low quality of the work. In order to internalise their concerns, a mechanism with appropriate provisions to involve community in tank management needs to be developed.
