Hydrologic Report for October 2017
October typically kicks off the dry season with comparatively little rainfall than the previous summer months. This year was no different as the Winter Haven area averaged 2.88 inches of gross rainfall for the 10th month of 2017. The amount of water loss due to evapotranspiration was calculated at 3.23 inches this month. Correcting for this water loss due to evaporation and plant use, lands the City in the red for months net rainfall at -0.35 inches – slightly deepening our year-to-date deficit to 0.86 inches (Figure 1). As the final few months of the year are typically drier, we must observe an unseasonable abundance of rainfall to end the year with a positive annual precipitation total.
Historic records show that the amount of precipitation received this month was fairly typical – the long-term average was right at 2.90 inches (Figure 2). It is interesting that the record low for October was observed relatively recently in 2010. The rainfall that year totaled at just 0.02 inches. This was the 2nd lowest monthly total for the period of record – beat only by a nil sum in April of 1967.
Winter Haven’s lakes are some of our most economically and ecologically important natural resources; with visitors coming from across the globe to live the lake life. Therefore, its important for the NRD to monitor surface levels not only to ensure they are usable, but because water quality is strongly associated with the volume of water in the lakes. Since Winter Haven is a purely rainfall driven system, the amount of precipitation we receive can impact things like wetland connectivity and nutrient concentrations.
Winter Haven has approximately 50 lakes, so monitoring the level of each one presents challenges. However, the 14 lakes on the Souther Chain are all connected via canals and surface levels are equalized. Since the Souther Chain spans a large area of the City, its surface level is generally representative of the region.
Partnering with the Lakes Region Lakes Management District, the NRD complies daily staff gauge reading on Lake Shipp to calculate monthly surface level averages for the Southern Chain. We can then compare surface levels to previous months as well as long-term levels.
October Surface Level Report
Average surface level (SL) for the Southern Chain of Lakes was reports at 132.04 feet above sea level for the month of October (Figure 3). This has placed the SL of the Chain well above the long-term monthly average and slightly above the normal range of 131.94 feet. While we did post a rainfall deficit this month, surface levels continued to rise. This is the most likely due to a time lag as rain water seeps into the water table and reach an equilibrium with the lake levels. Again, we are excellently poised with full lakes prior to the dry season.
Provided by: City of Winter Haven – Natural Resource Division
Your comment will be posted after it is approved.
Leave a Reply.