source water protection reduces water treatment costs for urban suppliers contributes to improved access to safe drinking water in rural communities and can potentially also provide water of adequate quality for other uses such as agricultural irrigation for example a recent modelling exercise by abell et al more than billion people over half of the world s urban population living in the cities in the area covered by this study could therefore potentially benefit from improved water quality as a result of nbs applied to their source watersheds including million people who live in watersheds located in countries in the bottomtenth percentile of the human development index as of abell etal forested riparian buffers serve to prevent pollution of rivers while providing shade that helps to reduce thermal pollution parkyn