Hydrology deals with the origin, occurrence, circulation, distribution, the physical and chemical properties of water and its interaction with living organisms. This text introduces students to the key concepts and methods in physical and engineering hydrology.

Hydrology deals with the origin, occurrence, circulation, distribution, the physical and chemical properties of water and its interaction with living organisms. Hydrology is an essential field of science since everything from tiny organisms to individuals to societies to the whole of civilization - depends so much on water. Hydrological engineering, also called water resources engineering, is a civil engineering specialty offered at both the undergraduate and graduate levels. Hydrological engineering is chiefly concerned with the flow and storage of water. Topics commonly covered include urban drainage, water supply, wastewater treatment, river management and coastal protection. Hydrological engineering also focuses on preventing floods and lessening the effects of floods, droughts and other natural disasters. Water is an essential resource that is required by all life on Earth. Studying the movement, availability, and quality of water are the jobs of a hydrologist. More specifically hydrologists study the chemical properties, biological interactions, and the physical processes that govern the water cycle. The water cycle or hydrologic cycle is a process by which water is continuously cycled around the earth. This happens through different pathways and at different rates but the central concepts remain the same. Water evaporates from the ocean, condenses as clouds, moves over land, and precipitates. From there it can enter ground water, evaporate again, or enter a stream or lake. It will eventually find its way back to the ocean either by falling as precipitation, flowing with a river, or by moving ever so slowly with ground water. The hydrologic cycle is also a process that transfers heat energy. Heat is transported pole ward by water being evaporated and then condensing which releases heat. Without the water cycle the climate would be much more frigid and areas away from the equator would be much less habitable. Hydrology is more significant these days because we plan ahead of time to deal with extremes (scarcity of water leading to droughts, and overflowing of water bodies leading to floods). This text introduces students to the key concepts and methods in physical and engineering hydrology.