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Groundwater Systems and Karst Features

Groundwater and surface water are two parts of a single, interconnected water system. They influence each other in many ways, affecting water supply, water quality, and aquatic ecosystems. Nearly all surface water features, such as streams, lakes, and wetlands, interact with groundwater. These interactions can involve the movement of water and chemicals between the two systems. For example, surface water can gain water from groundwater, or conversely, surface water can recharge groundwater. These exchanges are important because they affect the availability and quality of water resources. Managing water effectively requires understanding how groundwater and surface water work together. This understanding is essential for making informed decisions about water use and protection. Groundwater and surface water are not separate resources but are part of a unified system that must be considered together for sustainable water management.

Figures (10)

Water balance
Schematic of an aquifer showing confined zones, groundwater travel times, a spring and a well
Within a long period of groundwater depletion in California's Central Valley, short periods of recovery were mostly driven by extreme weather events that typically caused flooding and had negative social, environmental and economic consequences.[48]
Groundwater withdrawal rates from the Ogallala Aquifer in the Central United States
An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the water table (4), and three different wells (7, 8 and 9) dug to reach it.
Dzherelo, a common source of drinking water in a Ukrainian village
The entire surface water flow of the Alapaha River near Jennings, Florida, going into a sinkhole leading to the Floridan Aquifer groundwater
Groundwater may be extracted through a water well
Center-pivot irrigated fields in Kansas covering hundreds of square miles watered by the Ogallala Aquifer
Families collecting water from a water well in Niger.

Groundwater is water beneath the surface, stored in spaces between soil and rock. The top of this water is called the water table. Water moves through the ground in paths called flow systems.

For example, a gaining stream gets water from groundwater, while a losing stream gives water to groundwater. This exchange happens through the streambed and depends on the water levels of the stream and groundwater. Karst landscapes, like those with caves and sinkholes, are shaped by groundwater dissolving soluble rocks like limestone.

In these areas, groundwater moves quickly through underground channels, making the connection between surface water and groundwater especially strong.

Key Points

  • Ground water is the water in the saturated zone below the water table, which is completely filled with water and can be withdrawn using wells.
  • The zone of saturation is the area below the water table where all the voids in the subsurface materials are completely filled with water.
  • The water table is the upper surface of the saturated zone, and its configuration indicates the direction of ground-water flow.
  • An aquifer is a subsurface layer of permeable rock, sediment, or soil that can store and transmit significant quantities of water.
  • A confined aquifer is an aquifer that is overlain by a confining bed, which restricts the movement of water into or out of the aquifer.

Terms

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Sources & licensing(4)