Over the last decade, Sri Lanka has faced droughts, flooding, and food security scares and is struggling to rise from an economic crisis. Water is the lifeblood of all things living on Earth, and Sri Lanka has long neglected a once-robust network of arteries – ancient irrigation systems and a network of irrigation tanks which once fed and kept many parts of Sri Lanka fertile and green.

Water is at the centre of economic and social development. It influences whether communities are healthy places to live and whether farmers can grow food and also underpins the natural ecosystems. Sri Lanka depends on monsoon rainfall as the primary source for its water resources. Due to this, water supply is variable in space and time. According to some reports, between 75-80% of the island’s population resides in rural areas and depends on agriculture for their livelihoods. Water scarcity in the country’s Dry Zone makes cultivation difficult for part of the year and is a major constraint to development. Climate change aggravates this water scarcity further, monsoons are more erratic, and persistent droughts are common. Due to increased demands from agriculture, industry and urbanisation, water resources are being rapidly depleted. Several governments have made efforts to establish new water infrastructure, renovate existing dams and reservoirs, and promote improved irrigation technologies to meet the demand for agricultural water. However, the effort has never kicked off on a large scale.  Meanwhile, water-related challenges continue to increase. And the Island’s seasonal rainfalls have seen severe shifts, impacting two extreme conditions; floods and droughts. The island’s Dry Zone is home to approximately a third of its population of 22.5 million.

It is vital that, as Sri Lanka moves towards economic recovery, the island builds resilience to weather the many disruptions that can undo the progress achieved through austerity and sacrifice. One of the key focus areas should be rehabilitating the island’s ancient cascading tank systems, which are a vital part of Sri Lanka’s agricultural heritage, by taking a holistic approach to restore them as integrated hydrological, socio-economic, and ecological systems. Sri Lanka is blessed by a historical system of around 20,000 irrigation tanks, which includes 320 ancient large dams and man-made lakes that dot the lowlands, with over 10,000 reservoirs in the Northern Province alone. The world-famous 87 km-long Giant Canal (Yodha Ela) with a gradient of 10 cm per km is a prime example of the engineering brilliance of ancient Sri Lankans. Despite this ancient wisdom and heritage that equipped the island to store and manage water received by rainfall and mountain springs, poor governance, mismanagement, and the apathy of the responsible State agencies only about 11,000 tanks are in working order.

With the changing patterns of climate change in Sri Lanka, there is evidence to show that dry regions are becoming dryer, placing the services that the tank cascades have been providing even under  more pressure. Rainfall patterns are becoming unpredictable, and floods are becoming more frequent and severity increases. In the most recent floods in late November 2024, close to 460,000 people were affected. In addition to floods and droughts, growing socio-economic demands and lack of watershed management puts greater pressure on these functioning systems. Further, the siltation of tanks results in less water-holding capacity of small tanks, leaving the farmers vulnerable during heavy rainfall. The recent floods in early December 2024 could have been somewhat mitigated if these tanks had been dredged or silt removed on time. It goes without saying that the loss to the national economy from the loss of paddy and other crops is huge. According to a World Bank report, on average Sri Lanka experiences losses of Rs. 50 billion (US $ 0.17 billion) – approximately 0.4% of Gross Domestic Product (GDP) – from disasters, of which Rs. 32 billion is due to extreme weather events.

As such, the Government needs to craft a national policy for a well-planned, holistic and integrated approach to the management of water reservoirs with all stakeholders involved in the process. Rehabilitation of irrigation tanks using a cascade planning approach can help improve sustainability, while a reassessment of the existing regulatory framework and water governance is needed to improve the situation. Such an approach should have bi-partisan support for the effect and longevity of the process and to sustain the efficiency in the decades to come.