Surface-water hydrology, often referred to as simply hydrology, is the study of the movement, distribution, and quality of water on Earth's surface. There are several synonyms that can be used to describe this field of study, such as aquatic science, limnology, and water resources engineering. Aquatic science focuses on the study of freshwater and marine ecosystems, while limnology is the study of inland waters, including lakes, rivers, and wetlands. Water resources engineering focuses on the management and development of water resources for human use, such as irrigation and urban water supply. All of these synonyms relate to the study of water and its interactions with the environment.