Surface Water and Groundwater: What's the Difference?
Of all the water on Earth, more than 96% is too salty to drink. Most of that is in the oceans. Surface water—in lakes, rivers, creeks, ponds, and playas and other wetlands—is our most visible source of freshwater, but it makes up just one-fifteenth of the 1 percent of useable freshwater on Earth. The rest is tied up in frozen glaciers or is groundwater—stored in subsurface layers of rock and sediment.
The distinction between surface water and groundwater sounds more straightforward than it really is. The two often intermingle and one can quickly become the other. Through a spring, for example, groundwater runs out onto the Earth’s surface and becomes surface water. If that water then soaks back into the ground before it evaporates, is consumed by plants and animals, or runs into a body of water, it may seep into an aquifer and become groundwater again. Just as surface water can infiltrate aquifers, groundwater can migrate into lakes, rivers, and oceans.
Surface Water and Groundwater in Kansas
In Kansas, surface water is more abundant in the eastern part of the state, where higher annual precipitation replenishes rivers, lakes, and wetlands on a fairly regular basis. Groundwater is more plentiful in western Kansas, where the expansive High Plains aquifer provides almost all of the water used in the region. In between, surface water gets gradually less plentiful as annual precipitation totals drop from east to west. A number of aquifers underlie the state from east to west, but none are as widespread or used as extensively as the High Plains aquifer.