Evaluating the impacts of river pollution on ecosystem services: a case of Periyar River, Kerala

Abstract

River ecosystems have, since the advent of human civilization, served as key areas for human settlements, production, and infrastructure. With ever-increasing intensification of land use coupled with other radical changes like damming of rivers in recent years, there has been a shift in the functions and services available in riverine ecosystems. This underscores the need for understanding ecosystems at the level of the ecosystem services they provide. The Periyar River, often called the ‘Lifeline of Kerala’, is the longest in the state flowing through multiple towns and providing the basin with various essential services including drinking water, flood regulation, waste treatment, aesthetic and spiritual values, among others. However, in recent years, the river has been steadily undergoing eco-degradation, primarily owing to factors like industrial pollution, sewage discharge, and deforestation in the higher reaches. This thesis aims to study the impacts drivers of change like pollution can have on the services provided by a river ecosystem. Further, the extent of their impacts is analyzed spatio-temporally. Ecosystem services – defined as the ‘various benefits humans derive from ecosystems in the form of goods and services’ – are crucial to human well-being and it can be directly impacted by changes to ecosystems. Evaluation of ecosystem services has thus been growing as a popular method to create an important argument towards improving their visibility in decision-making processes, apart from significantly validating the need for ecosystem conservation. The study has been carried out along four objectives: i) identifying the key parameters of pollution, ii) identifying and examining the key ecosystem services provided by the river, iii) mapping and analyzing the temporal changes in the ecosystem and its services as a result of pollution, and further iv) suggesting suitable strategies to address the problems associated with river pollution. A comprehensive literature review was undertaken to study and extract various methodologies for examining the impacts of river pollution on ecosystem services. For the identification and quantification of ecosystem services, various ecosystem assessment toolkits were studied such as the Millenium Ecosystem Assessment (MEA), the Common International Classification of Ecosystem Services (CICES), and The Economics of Ecosystems and Biodiversity (TEEB). Methods for the economic valuation of ecosystem services like benefit transfer, avoided costs, and others were studied as well.