Village Tank Cascade Systems

The Healthy Landscapes project is rehabilitating and promoting the sustainable management of Village Tank Cascade Systems (VTCSs). Find out more about this ancient water management system below.

How dry is Sri Lanka’s dry zone?

Sri Lanka has two distinct monsoon seasons: the Maha season (September – March) and the Yala season (May – August). The country can be divided into three distinct zones based on the amount of rainfall received during these seasons:

  1. The wet zone, found in the southwest, receives an average annual rainfall of over 2,500 mm.
  2. The intermediate zones found in the eastern and central regions, receive between 1,750 mm and 2,500 mm.
  3. The dry zones, found in the south and northwest, receive less than 1,750 mm.

While relatively dry compared to the other two zones, Sri Lanka’s dry zone is certainly not as dry a desert-which receives only about 250 mm of rain per year!

Several centuries ago, as populations expanded into the dry zone of Sri Lanka, efficient water storage and management became a high priority.


Most rivers and streams found in the country’s dry zone are seasonal, emerging only during the monsoon season, with their flow dependent on the amount of rainfall received. The resourcefulness of ancient communities led to the creation of VTCSs or Ellangawa (made up of the Sinhalese words ‘ellan’, meaning hanging and ‘gawa’, meaning one after the other) which store and distribute rainwater. When fully functional and well managed, this system provides surrounding villages with a year-round water supply, thus helping the surrounding landscape and communities to thrive.  

VTCSs consist of an intricate network of small to very large tanks (or reservoirs), that are connected through a series of canals.  They are organized in succession- starting from those at the highest elevations- and all drain into a ‘village tank’. The tanks each have specific purposes. For example, the village tank is used for irrigation, as well as other community activities, while the ‘water hole’ is constructed for the trapping and deposition of silt.