Cascade Tank Water Quality Management: A Case Study in Thirappane Tank Cascade System, Sri Lanka

Abstract

Tank cascade system (TCS) is a series of tanks located in a mesocatchment and has been accepted as a Globally Important AgriculturalHeritage System found in Sri Lanka. Ecosystem components of theTCS play a major role in purifying water within the system. Thisstudy attempted to investigate the water quality status and the farmers’willingness to rehabilitate the ecosystem components of the ThirappaneTCS. Drinking and irrigation water quality parameters were tested in34 locations and drinking and irrigation water quality indexes werecalculated. Participatory rural appraisal and a questioner survey wereconducted to gather social data. Water of TCS was observed to beappropriate for irrigation but not for drinking during the Maha croppingseason. Based on the results of the Nitrate (as NO3- ) and Total Phosphate(as PO4 3-), water of TCS can be categorized as eutrophic. Presenceof ecosystem features of tank cascade system, annual income of therespondents, satisfaction on the quality of water for drinking, and theawareness about the tank cascade system significantly influenced theparticipatory decisions of the community on the rehabilitation of TCS.This study shall be an example and an eye opener to formulate sustainabletank cascade management plan.