106 REPORT OF INVESTIGATIONS NO. 50
Water moves downgradient from areas of high piezometric level to areas of low piezometric level. In general, the direction of movement, shown by the arrows in the figures, is at right angles to the contour lines, although locally the direction of flow may be different because of differences in permeability such as caused by cavern systems.
Figure 46 depicts the piezometric levels in September 1960, the highest observed during the investigation. The high levels of September 1960 equalled or exceeded the highest previous recorded levels which occurred in the early 1930's. Figures 47 and 48 which show the piezometric surface in July 1961 and December 1963 represent about normal conditions; figure 49 shows the piezometric surface in May 1962 when artesian levels were at their lowest for the period of record 1943 through 1963. The relation of the piezometric surface to the land surface is shown in figures 50 and 51. Figure 50 shows the distance above and below land surface of the static water level in tightly cased wells in the Floridan aquifer during extremely high-water conditions (Sept. 1960). Figure 51 shows the distance above and below land surface of the static water level in tightly cased wells in the Floridan aquifer during extremely low-water conditions (May 1962).
Fluctuations
Gages were installed on six wells in the Floridan aquifer to record the fluctuations of the piezometric surface (figures 37, 41, 52, and 53). In addition, water levels were measured periodically in about 70 wells. Most water-level fluctuations are caused by changes in rates of recharge (mostly rainfall) and/or discharge. However,, variation in barometric pressure, temporary loading of the land surface such as by-passing of trains and earthquakes also cause fluctuations. For example, the Alaskan earthquake of March 27, 1964 created a brief surge of more than 10 feet in the water levels of some wells in Orange County.
The sharp rises in the water levels in well 833-120-3 at the Orlando Air Force Base (figure 52) and well 932-128-1 west-of Orlando (figure 53) are caused by rapid recharge through the many drainage wells in the area. The nearly equally sharp declines following the rises show that the water mound created by the drainage wells rapidly dissipated through the porous limestone. Although the water probably moves slowly, the pressure is transmitted relatively rapidly to other parts of the aquifer