A new report finds communities along the Charles River will experience an appreciable increase in flooding within the next 50 years. Due to climate change, extreme storms that are less common now are expected to become more frequent and discharge a higher amount of water. Using these existing rainfall predictions, a Charles River Watershed Association report modeled the impact of future storms on 20 towns along the river and found many places where flooding could damage key infrastructure, including in Newton, Dedham, Watertown, Waltham and Wellesley.