Groundwater is one of our most important and widely available resources. Yet people's perceptions of groundwater are often and incorrect The reason is that groundwater is hidden from view ex in caves and mines, and the impressions people gain from these subsurface openings are often misleading observations on the land surface give an impression that Earth is solid. This view is not changed very much when we enter a cave and see water flowing in a channel that appears to have been cut into solid rock Because of such observations, many people believe that groundwater occurs only in underground rivers" But actual s flood rivers underground are rare
In reality, most of the subsurface environment is not solid at all. It includes countless tiny pore spaces between grains of soil and sediment, plus narrow joints and fractures in bedrock. from Together these spaces add up to an immense volume. It is in these inner tiny openings that groundwater collects and moves.