Hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust Hydrogeology is a branch of the earth sciences dealing with the flow of water through aquifers and other shallow porous media. The very shallow flow of water in the subsurface is pertinent to the fields of soil science, agriculture and civil engineering, as well as to hydrogeology. Hydrogeology looks at how water interacts with geological systems. But there is more to hydrogeology than wet rocks. Water is a vital natural resource for people all around the world - whether it is piped to homes or drawn out of wells. Understanding where it is and how it moves under the ground is essential in protecting this resource. Hydrogeologists study the distribution, flow and quality of water underground. This involves interpreting technical data and information from maps and historical documents to build a conceptual model of groundwater flow and quality; designing and completing an investigation, which may include environmental measurement and sampling or an ongoing monitoring regime, in order to confirm or develop the model; using modelling techniques to enable predictions to be made about future trends and impacts on groundwater flow and quality. Some parts of the world are blessed with frequent rainfall and plentiful surface water resources, but most countries need to use the water that is stored underground to supplement their needs. Hydrogeologists can help by locating suitable reserves and by assessing how much water it is possible to extract without permanently damaging underground aquifers or surrounding ecosystems. By looking at the way that groundwater flows, hydrogeologists can also identify when it is at risk from pollution and how we can protect it by careful planning and land-use. Without the knowledge that hydrogeology gives us we have no way of predicting what will happen to our water resources or the future effects on the environment of water extraction. This book ephasizes on understanding of hydrogeology; to describe wide-reaching progress in hydrogeology; and a reference tool for, researchers, engineers, scientists, and practitioners in developing and industrialized countries.