Hydrodynamics is a very rich area of study, involving some of the most intriguing theoretical problems, considering our present level of knowledge. General nonlinear solutions, closed statistical equations, explanation of sudden changes, for example, are wanted in different areas of research, being also matter of study in Hydromechanics. Further, any solution in this field depends on many factors, or many “boundary conditions”. The changing of the boundary conditions is one of the ways through which the human being affects its fluidic environment. Changes in a specific site can impose catastrophic consequences in a whole region. For example, the permanent leakage of petroleum in one point in the ocean may affect the life along the entire region covered by the marine currents that transport this oil. Gases or liquids, the changes in the quality of the fluids in which we live certainly affect our quality of life. The knowledge about fluids, their movements, and their ability to transport physical properties and compounds is thus recognized as important for life. As a consequence, thinking about new solutions for general or specific problems in Hydromechanics may help to attain a sustainable relationship with our environment

Traditionally, hydrogeology is defined as the area of geologic sciences, as well as engineering, that in its broadest sense deals with water below the land surface. Hydro is the Greek word for water, and geology is the science of Earth: geo being a prefix derived from the Greek word gaia (meaning the earth, but also Gaia – a primordial Earth goddess in Greek myth), whereas logy is derived from the Greek word logos which means word, thought, principle, or speech, but in modern times is most commonly understood to mean science. Thus, geology literally means the science of Earth.

This book is about the study of hydrogeology and the significance of groundwater in the terrestrial aquatic environment. Water is a precious natural resource, without which there would be no life on Earth. We, ourselves, are composed of two-thirds water by body
weight. Our everyday lives depend on the availability of inexpensive, clean water and safe ways to dispose of it after use. Water supplies are also essential in supporting food production and industrial activity. As a source of water, groundwater obtained from beneath the Earth’s surface is often cheaper, more convenient and less vulnerable to pollution than surface water.

Inadequate in situ observations have been historical barriers in the development of hydrologic science. Additionally, with the changing climate and ever accelerating human activities, it is anticipated that water-related disasters such as flood, landslide, and drought will be more severe and frequent, thus threatening more regions around the world. Flooding, which is considered as one of the most hazardous disasters in both rural and urban areas, accounts for around one-third of all global geophysical hazards and causes significant human suffering, loss of life, and property damage.