| description:
|
A spring is defined as a place where groundwater flows naturally onto the land surface or into a body of surface water. A spring's occurrence depends on the nature and relationships among topography, underlying geologic strata, and aquifer water levels. While some springs are isolated features, many are clustered into spring groups of varying size and areal extent. In addition to providing a unique recreational resource, springs provide important base flow to rivers and streams and critical habitat to plants and animals. Most springs in SJRWMD occur in discharge areas of the Upper Floridan aquifer where limestone is at or near land surface, or where the sediments overlying Floridan limestone have been breached. The majority of the springs in SJRWMD are located along the major river systems of the St. Johns, Ocklawaha, and Wekiva rivers. This data layer also includes surficial aquifer springs, which are now called seeps, under nomenclature recently agreed upon by the Florida Geological Survey. Springs are classified by magnitude based on the volume of flow, or discharge of water. The amount of water that flows from a spring depends on several factors, including rainfall, size of the caverns within the rocks, the water pressure in the aquifer, and the size of spring recharge basin. Human activities can also influence the volume of water that discharges from a spring; for example, increased groundwater withdrawals can reduce the hydraulic pressure in an aquifer, causing water levels to decline and spring flows to decrease. Since springs have dynamic flows dependent on climate, hydrogeology, and others factors, a spring classified as being a certain magnitude at one time may not continue to flow at that rate at other times. Springs are classified by magnitude, which is based on the median value of all discharge measurements for the period of record. First magnitude springs discharge the greatest amount of water. The following is a summary of spring classification magnitude by discharge. |