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LandAp is a water balance computer application that estimates storage requirements and wet-weather discharges for slow rate land application systems. It uses rainfall, reclaimed water inflow, evapotranspiration and ground water outflow to determine the amount of storage needed for times when the water cannot be applied. LandAp is mentioned in Chapter 62-610, F.A.C., (Reuse of Reclaimed Water and Land Application) as an example of an analytical means by which storage can be estimated.

Last year, DEP contracted with the University of Florida, Department of Agricultural and Biological Engineering, to create a new version of LandAp, now named LandAp2010. LandAp2010, developed by Dr. Chris Martinez, Dr. Bin Gao and researcher Mayank Thepadia, is a spreadsheet-based modeling package that accesses an internal database of recent climate data and allows for the entry of site specific parameters to calculate water storage needs. The new LandAp2010 is easier to use, provides more information, and is adaptable to a wider set of conditions than the previous version.

New and/or updated features include:

  • A database of 74 weather stations that meet the 20-year minimum data requirement
  • Refined methods for determining plant-specific evapotranspiration
  • A nitrogen balance for the evaluation of nitrogen loading to ground water
  • Input fields to allow for either constant or monthly values for hydraulic loading rate, hydrologic site capacity and surface runoff coefficient
  • Input field allowing for the choice of common crops or the input of custom crop parameters


LandAp2010 is a Microsoft Office Excel 1997-2003 compatible spreadsheet and uses Visual Basic for Application macros and ActiveX controls for some of its calculations. To use the spreadsheet, macros need to be enabled.

Download LandAp2010 (MS Excel - 6.74 MB)

Download User Manual (Adobe PDF - 2.4 MB)

More Information

For more information about LandAp2010, or if you have questions about its use, please contact the FDEP Water Reuse Program.

Last updated: September 21, 2011

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