INTRODUCTION OF ENGINEERING HYDROLOGY :
Hydrology is the science of water. The word hydrology comes from the Greek words hydro (water) and logos (study). Hydrology is an extremely important field of study, dealing with one of the most valuable resources on Earth: water.
All aspects of the Earth’s available water are studied by experts from many disciplines, from geologists to engineers, to obtain the information needed to manage this vital resource. Hydrologists rely on their understanding of how water interacts with its environment, including how it moves from the Earth’s surface, to the atmosphere, and then back to Earth. This never-ending movement is called the hydrologic cycle, or the water cycle.
Water takes on various forms in the environment in response to changes in temperature and other influences. Water from the surface of oceans and other bodies of water is warmed by the sun and evaporates as water vapor.
As this moist air rises high into the atmosphere, it cools and condenses into clouds. Moisture in the clouds then returns to the Earth’s surface as precipitation.