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geer > 2000 > poster > synthesis on the impact of 20th century water-management and land-use practices on the coastal hydrology of southeastern florida > temporal changes in the ground-water flow system

Synthesis On The Impact of 20th Century Water-Management And Land-Use Practices On The Coastal Hydrology Of Southeastern Florida

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Abstract | Saltwater Intrusion | Land Use and Land Use Cover | Surface Water Conveyance System | Municipal Water Use | Agricultural Water Use | Ground-Water Flow System | Canal Stage and Discharge | Impact on Ecosystem

Temporal Changes In The Ground-Water Flow System

October 1940 to 1944
map of ground-water flow system October 1940 to 1944

distance scale

[larger image]

October 1990 to 1994
map of ground-water flow system October 1990 to 1994

distance scale

[larger image]

triangle representing surface water control point
Surface water control point
circle representing well control point
Well control point
dashed line used to indicate county line
County Line
blue colored line used to indicate canal
Canal
green line showing potentiometric surface
Line showing potentiometric surface, dashed
where uncertain, altitude in feet

Water-table contour maps shown here illustrate five-year 'average' conditions that existed during the months of October 1940-44 and October 1990-94. Accordingly, the reader should be careful not to confuse these maps with synoptic potentiometric surface maps. In southeastern Florida, water levels are highest in September or October and lowest during April or May. A five-year interval of time was used to dampen or smooth the effect of unusually wet or dry months.

Maps showing average conditions were prepared to examine temporal and spatial changes in the flow system resulting from development of the present-day surface water conveyance system. The October 1940-44 map shows conditions prior to development of that conveyance system. In the early 1940's, the levee system, most canals, water conservations areas, and gated salinity control structures had not been constructed. By 1990-94, the water management system evolved to include hydraulic control structures, and a system of levees, impoundments, and conveyance canals affecting both the altitude and configuration of the water table. Such features were designed to control flooding in urban and agricultural areas during the rainy season, impound water and provide recharge to the underlying aquifer, retard the inland advance of the saltwater within the aquifer, and provide adequate municipal and agricultural water supplies.

Note: The information in this legend relates to the four maps below
dashed line used to indicate county line
County Line
blue colored line used to indicate canal
Canal
green line showing potentiometric surface
Line showing potentiometric surface, dashed
where uncertain, altitude in feet
Average differences
in water levels

color gradient from orange to blue used to indicate average differences in water levels

Average difference in water levels between April 1940-44 and April 1990-94
average difference in water levels between April 1940 to 1944 and April 1990 to 1994

distance scale

[larger image]


Average difference in water levels between October 1940-44 and October 1990-94
average difference in water levels between October 1940 to 1944 and October 1990 to 1994

distance scale

[larger image]


Average difference in water levels between April 1970-74 and April 1990-94
average difference in water levels between April 1970 to 1974 and April 1990 to 1994

distance scale

[larger image]

Average difference in water levels between October 1970-74 and October 1990-94
average difference in water levels between October 1970 to 1974 and October 1990 to 1994

distance scale

[larger image]

A well hydrograph can illustrates only the temporal change in ground-water levels at only a single site. Maps shown here illustrate both temporal and spatial water level changes that occurred during the last 60 years of the 20th century. These maps illustrate the temporal change in 'five-year average' water levels that occurred between 1990-94 and 1940-44, 1990-94 and illustrate the temporal change in 'five-year average' water levels that occurred between 1990-94 and 1940-44, 1990-94 and October 1990-94 appear to have declined in large inland areas when compared to the average conditions that existed during the months of April 1940-44 or October 1940-44. This is assumed to be the result of water management efforts to control urban and agricultural flooding. Water levels along the coast seem to be, on average, higher during the 1990-94. This is assumed to be the result of water management efforts to control saltwater intrusion. Conversely, a comparison of water level maps for October 1970-74 and October 1990-94 suggests that, on average, similar hydrologic conditions existed in Broward and Miami-Dade Counties. Conditions appear to be more variable in Palm Beach County on the basis of this same comparison.


Next: Temporal Variation In Canal Stage and the Canal Discharge

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For more information contact:

Bob Renken
U.S. Geological Survey
9100 N.W. 36th Street Suite 107,
Miami, FL, 33178
Phone: (305) 717-5822
Fax: (305) 717-5801
EMAIL: rarenken@usgs.gov

Related information:

SOFIA Project: Synthesis on the impact of 20th Century water-management and land-use practices on the coastal hydrology of southeast Florida

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Last updated: 04 September, 2013 @ 02:07 PM (KP)