MIT Professor Emeritus Peter S. Eagleson, an accomplished and influential hydrologist who helped revolutionize the field, died of natural causes on Jan. 6 at the age of 92. Eagleson started working at MIT in 1952 and served as the head of the Department of Civil and Environmental Engineering from 1970 to 1975. He was a pioneer in the field of hydrology, transforming it from an engineering specialty with local application into the global-scale study of the water cycle. His 1970 book, titled “Dynamic Hydrology,” provided a radically new perspective on…