By Mohan Seneviratne*
COLOMBO, Sri Lanka | 16 January 2025 (IDN) — Water is at the centre of economic and social development. It influences whether communities are healthy places to live, whether farmers can grow food and underpins natural ecosystems. Moreover, humans experience Climate Change through water be it floods, droughts, cyclones or tsunamis. Sri Lanka is famed for its water reservoir management built by kings who understood the value of water for life and food security.
The rainwater reservoirs developed in the ancient kingdom of Anuradhapura (437 BCE-845 CE) and Polonnaruwa (846 -1302 CE) in the dry zone of Central Lowlands of the island resulted in two seasons of rice farming. This was well understood by the ancient kings of Sri Lanka as seen by the famous quote from King Parakramabahu who built the Parakrama Samudrya (Ocean).
“Not a single drop of water received from rain should be allowed to escape into the sea without being utilised for human benefit” – King Parakrama Bahu the Great (1153–1186 CE).
Today there are in total around 21,456 tanks including 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.
Another is the unique sluice gate used in tanks for controlled release. The cascades of small tank networks are one of the country’s greatest legacies from a remarkable hydraulic civilization that provided a solution for water scarcity in the dry zone. The cascade system enabled the water from one tank to flow to the next ensuring minimal wastage. Thus, maintaining the water balance in the ecosystem, replenishing groundwater and supporting biodiversity.
Overall, the construction of the tanks demonstrated advanced knowledge of soil, hydrology and environmental sustainability. These have been supplemented by water reservoirs built in the last 50 years like the giant Senanayake Samudraya. The ancient water tanks were not merely utilitarian but were integral to the culture, economy, and spirituality of the people.
Today, sadly as a result of mismanagement and apathy of the responsible agencies only about 11,000 tanks are in working order.
Globally by 2030, food production will need to double and meet a significantly higher demand for calories driven by population growth and increased per capita calorie consumption. On the supply side, the amount of arable land is decreasing by 1% per year, and more than 90% of global soils could be degraded by 2050, reducing overall food production by 2050.
Moreover, under the threats of Climate Change and the unprecedented economic crisis that has exacerbated food security in Sri Lanka, the role of tank cascade networks has become even more crucial.
With the changing patterns of Climate Change in Sri Lanka there is ample evidence to show that dryer regions are becoming dryer, placing the services that the tank cascades have been providing under even 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 465,746 people were affected.
In addition to floods and droughts growing socio-economic demands and lack of watershed management puts greater pressure on these systems. 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 were desilted in a timely manner.
The loss to the national economy from loss of paddy fields is humongous. According to a World Bank report, on average Sri Lanka experiences losses of LKR 50 billion (USD 0.17 billion) – approximately 0.4% of Gross Domestic Product (GDP) – from disasters of which LKR 32 billion is due to extreme weather events[1].
Therefore, Sri Lanka urgently needs a holistic integrated approach to management of water reservoirs with the participation of Central Government Agencies and the Divisional Secretariats if it is to address timely repair of water tanks, siltation removal and flood management.
These should include:
- Rehabilitation of tanks using a cascade planning approach improves sustainability.
- Compared to the ad hoc rehabilitation of individual tanks, a cascade approach helps planners capture any benefits arising from the joint rehabilitation of tanks, for example groundwater recharge and avoids conflicts between water users.
- Participatory planning produces key information leads to better decisions.
- Multistakeholder engagement and coordination at the village level to the divisional secretariat.
- Simplifying the regulatory framework and water governance
- A reassessment of the existing regulatory framework and water governance. Currently 40 state agencies across various line ministries are responsible for water management without an overarching apex body.
- Rural sector participation generates additional income to the community
- Rural development programs generates additional income to the community by engaging them to protect and repair critical infrastructure.
- Private sector participation in financing capital works
– The private sector needs to be encouraged to provide loans at low interest rates, in the form of SME loans to collectives for repair of infrastructure.
For the first time in decades, in November last year, the Sri Lankan government approved the import of a large consignment of rice – the country’s staple diet. This is thus the opportune time for the government to take a holistic view to improving rice production through sustainable water management and water reservoir management.
* Mohan Seneviratne was the Global Thematic Water Lead at the International Finance Corporation, the private sector arm of the World Bank Group from 2011 to 2019. He has over 40 years of experience in water conservation, water management and water treatment. Every Drop Counts Business program he conceptualized and implemented for Sydney Water won the prestigious Stockholm Industry Water Award in 2006. He also published several books including “A Practical Approach to Water Conservation for Commercial and Industrial Facilities” (Elsevier, 2007).
Photo: Para Samudra is the man-made lake built during the King Parakaramabhahu era which is still an important water reservoir for Sri Lankan farmers. Credit: Kalinga Seneviratne.
[1] World Bank, “Fiscal Disaster Risk Assessment and Risk Financing Options”, March 2016.
