The Water Cycle in Volusia County
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Prepared in cooperation with Volusia County The Water Cycle in Volusia County Earth’s water is always in motion. The water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the Earth’s surface (fig. 1). This fact sheet provides information about Evapotranspiration how much water moves into and out of Volusia County, and where Rainfall it is stored. It also illustrates the Seepage from land surface to seasonal variation in water groundwater Groundwater and Surface-water quantity and movement using Outflow data from some of the hydrologic Groundwater seepage data collection sites in or near and spring discharge to land Volusia County (fig. 2). surface Where is the water and how does it move in Volusia County? Figure 1. Major components of the water cycle. Basic Concepts Most of the water in Volusia County Irrigation water that is not used by the is stored in three types of places—the plants seeps (percolates) into the ground Water that comes from the clouds in atmosphere (where water occurs in as recharge to the aquifers. Residents of the form of rain is known as precipitation. water vapor and droplets); surface-water Volusia County also use water pumped Water from the clouds falls to the Earth features such as lakes, wetlands, and from the aquifers for drinking water and and runs downhill into streams and lakes streams; and in underground reservoirs for household activities such as cleaning, as surface runoff. Some of this runoff known as the aquifers. The amounts of bathing, and flushing the toilet. Some of percolates into the soil and deep into the water in these three individual places are this water ends up as wastewater and is ground to be stored in the aquifer. Water constantly changing as water moves from treated in septic tanks or, more com- travels from the aquifer through the one place to another. monly, is discharged into sewers that springs back up to surface streams or to Human activity affects the move- transport the wastewater to wastewater the ocean. Water transpires from plants ment of water between the three distinct treatment plants. Septic-tank drainage and trees and evaporates from the Earth’s storage places. For example, some people seeps back into the ground as does treated surface and the ocean, returning to the use water from lakes, streams, or aqui- wastewater that is put into percolation atmosphere. Together these two processes fers for irrigating lawns and crops, or in ponds or sprayed onto the land surface at are called evapotranspiration, or ET. The industrial activities such as generation some wastewater treatment plants. How- water vapor from ET condenses to form of electricity. Irrigation water is used ever, in most coastal communities and clouds which produce precipitation that by grass and other plants during photo- near the St. Johns River, treated waste- falls back to the earth. This cycle of the synthesis. Some of the water taken up water is discharged directly into rivers or never ending movement of water on the by plants is returned to the atmosphere estuaries and flows from the county. Earth is called the water cycle. through the process of transpiration. U.S. Department of the Interior Printed on recycled paper Fact Sheet 2009-3004 U.S. Geological Survey October 2009 81°30’ 81°00’ Water does not only move from one storage place to another. It is also in motion as streamflow on the land surface Atlantic Ocean FLORIDA and as groundwater flow through the 29°30’ aquifers beneath the land surface. This Volusia Crescent County motion is driven by gravity, as the natural City 95 behavior of water is to “flow downhill”; Gulf of that is, from locations with higher water M idd Mexico L le i levels to those with lower water levels. t H Creek t l a e w H C PUTNAM COUNTY r Most streams in Volusia County begin a e w e VOLUSIA COUNTY k within the county and flow into the Lake George Halifax ATLANTIC OCEAN Tomoka coastal estuaries, the St. Johns River, FLAGLER COUNTY River or Flagler County (fig. 2). Likewise, VOLUSIA COUNTY Holly Hill Daytona the flow of groundwater is mostly from Tiger Beach Bay Volusia County to the areas with lower Canal River St. water levels, such as the St. Johns River, Deep Creek De Leon the coastal estuaries, the Atlantic Ocean, Springs and parts of surrounding counties. Little F LAKE COUNTY De Leon MARION COUNTY John’s ce C groundwater flows into Volusia County. Springs pru ree S k New Smyrna Thus, most of the water in Volusia River Beach County, both surface water and ground- 29°00’ Deland water, is of “local” origin, as it ultimately Lyonia F 4 Blue Preserve results from the rain that falls directly on Springs the county. Deep Of course the St. Johns River, on the western edge of Volusia County, drains Lake Creek Monroe Cow Creek 95 parts of Volusia County and also a large area to the south of Volusia County. The Sanford BREVARD COUNTY Lake St. Johns River is not considered in the Harney water budget because flow in this river is along the edge of the county rather than through it. EXPLANATION Kennedy MAJOR DRAINAGE DIVIDE SEMINOLE Space Center LakeF ApopkaSPRING COUNTY Storage of Water in the Atmosphere RAIN GAGE ORANGE COUNTY Indian River EVAPOTRANSPIRATION STATION There is always some water in the STREAM GAGING STATION atmosphere. Clouds are, of course, the visible condensation of atmospheric 28°30’ 0 5 10 MILES water, but even clear skies contain some 0 5 10 KILOMETERS water—water in particles that are just too small to be seen. The total amount of atmospheric Figure 2. Surface drainage features and locations of hydrologic data stations. water vapor in a vertical column of air (often called the precipitable water, or PW) is measured daily by the National 3 Weather Service with radiosondes (weather balloons). The highest daily MINIMUM AVERAGE water-vapor content measured at the MAXIMUM Kennedy Space Center radiosonde station (about 20 miles southeast of Volu- 2 Figure 3. Total daily water- sia County) between 1983 to 2005 would vapor content by month, be equivalent to a water depth of about 1983-2005 (data furnished 2.6 in. (inches) on the Earth’s surface by NOAA, from radiosonde (fig. 3). This is less than the amount of IN INCHES 1 station at Kennedy Space rainfall that can be produced from a sin- Center). gle thunderstorm in just a few minutes! Thunderstorms often produce amounts of rain that exceed the water-vapor content TOTAL DAILY WATER-VAPOR CONTENT, WATER-VAPOR DAILY TOTAL of the overlying atmosphere. This excess 0 J FMAMJJASOND of rainfall over water-vapor content can 1983-2005 occur because colliding air currents can 10,000 1,000 Figure 5. Annual water budget for Volusia County 100 (adapted from Rutledge, 1985). All quantities except rainfall are outflow from the 10 county, and are in inches WATER STORAGE, IN INCHES WATER over the entire county. 1 ATMOSPHERE LAKES AQUIFERS EXPLANATION RAINFALL–53 inches Figure 4. Estimated average water storage in Volusia EVAPOTRANSPIRATION–39 inches County. (Amount of storage is equivalent to depth of water STREAMFLOW–11 inches over the entire surface of Volusia County. Each horizontal SPRING AND FLOWING WELL DISCHARGE–2.3 inches GROUNDWATER FLOW–0.7 inches line represents 10 times more water than the line below it). bring additional water vapor from (Fernald and Purdum, 1998), there are not aquifers. A more detailed description surrounding areas into the storm. a few lakes of sinkhole origin which of the ground-water system for Volusia The average daily atmospheric could be more than 100 ft in depth. For County has been provided by several water-vapor content, based on data for example, the assumption that an average investigators, including Knochenmus and 1983 through 2005, is equivalent to only lake water depth is 10 ft suggests that the Beard (1971), Rutledge (1985), Kimrey about 1.3 in. This is a relatively small total amount of water contained in (1990), and Williams (2006). amount of water as compared to the all Volusia County lakes would be about Most of the groundwater in Volusia amounts of water contained in surface- 35 billion cubic feet, which would be County is contained within the Floridan water and groundwater storage. Although equivalent to a water depth of about aquifer system. Estimates of the amounts the atmosphere may not be a great store- 12 in. distributed over the entire county. of water contained in this aquifer can house of water, it is the superhighway Other surface-water features were be made by multiplying the volume used to move large quantities of water not included in this estimate of surface- (lateral area multiplied by thickness) by from one location to another. water storage on the land surface because the porosity of the rock. Porosity is a the areas or depths of water have not measure of the relative volume of empty Storage of Water on the Land Surface been documented. These include smaller space within the rock that can be Lakes are the most important lakes, wetland areas that contain water at occupied by water. Porosity of the vessels for surface-water storage in least part of the year, and the water that is Floridan aquifer system is variable; Volusia County. There are at least flowing in streams. however, an approximate average 239 lakes in Volusia County that are porosity can be used to estimate how Storage of Water in the Ground 10 acres or more in size (Florida Board of much water is contained within the Conservation, 1969).