Hydrogeology is the location of geology that offers with the distribution and movement of groundwater inside the soil and rocks of the Earth's crust. The terms groundwater hydrology, geohydrology, and hydrogeology are frequently used interchangeably. A hydrogeologist is someone who studies the methods that groundwater (hydro) moves thru the soil and rock of the earth (geology). A similar career, a hydrologist, is someone who studies surface water. Water is a crucial part of life on earth and is something that people, plants and animals want to live on.