April 2019 Hydrology Report
Precipitation
The City of Winter Haven received a total of 2.3 inches gross rainfall during the month of April. According to historic records, April averages 2.6 inches with normal rainfall ranging from 0.8 to 4.4 inches. Not only does this mark the third consecutive month of below-average rainfall during 2019, but also the third month that evapotranspiration exceeded gross rainfall. The resulting net rainfall equaled -2.08 inches–a deficit for the Winter Haven area this month. This loss of water is not out of the ordinary, however. Typically, rainfall begins to exceed evapotranspiration in June as we enter the Florida wet season. The following chart displays the current monthly rainfall for the 2019 year so far (Figure 1). The Year Selector option allows for a visualization of rainfall from previous years.
Figure 1
Surface Level
The response to this rainfall deficit can be observed in the change in surface level on the South Chain of Lakes. The monthly average Southern Chain level dropped from 131.9 ft in March to 131.7 ft in April. Not only is this minor decline in lake levels normal for this time of year, but the surface elevation for these lakes continue to remain well above the April average of 130.5 ft ans well as above the normal high of 131.5 ft. Figure 2 illustrates this change of lake levels in response to rainfall.
Figure 2
Groundwater
A similar response can be seen in the surface of the Upper Floridan Aquifer (UFA). The monthly average level of the UFA as observed via a monitoring well in downtown Winter Haven was 113.4 ft above sea level in April. As with lake levels, the UFA elevation continues to drop in accordance with net rainfall values. Despite this, the current level is still well above the long-term April average of 113.4 ft as well as above the high end of the normal range. As we move into the Florida wet season, the aquifer will likely remain high as the Summer months are typically when groundwater recharge occurs. Figure 3 displays monthly UFA levels in relation to historic means and normal ranges.
Figure 3