What would typically be found in a groundwater reservoir?

A groundwater reservoir typically contains sand and gravel deposits because these materials are particularly effective at storing and transmitting water. Sand and gravel have interconnected pore spaces that allow rainfall and surface water to percolate down through the soil layers, replenishing the groundwater. Unlike solid rock formations, which may have very few pore spaces and thus limit the movement of water, or open air, which does not retain water, sand and gravel provide an ideal medium for groundwater storage. This characteristic makes them crucial components in aquifers, which are natural underground reservoirs from which water can be extracted for various uses. Surface water would also not be found as part of a groundwater reservoir since it refers specifically to water that is found above ground, such as in lakes and rivers.