The clues used by scientists to find groundwater are the topography of a location, its vegetation and the location of wells. A scientist looking for water, or hydrologist, is generally concerned with finding large quantities of shallow groundwater.
The conditions for shallow ground water to be located in sufficient quantities are much more favorable under valleys than under hilly areas. Water may be located at swamps and streams but may not be in sufficient quantities. The type of vegetation in the area is another clue for the hydrologist. The presence of water-loving plants and trees, such as cottonwoods or willows, are good indicators of groundwater at shallow to moderate depths.
Scientists also look at maps that depict cross sections of the rocks in an area along with the number and positions of various kinds of rocks. Long layers of sedimentary formations are a sure sign of an underground water supply.
Wells are another clue as to the presence of groundwater and its quality.