library(tbeploads)Groundwater loads to Tampa Bay are estimated using the three-aquifer
framework from Zarbock et al. (1994). The anlz_gw()
function computes monthly TN, TP, and hydrologic loads for all bay
segments.
Methodology
Three aquifer types contribute to each bay segment each month.
Floridan aquifer: Flow is estimated with Darcy’s Law: Q = 7.4805 x 10^-6 x T x I x L, where T is transmissivity (ft²/day), I is the hydraulic gradient (ft/mile), and L is the flow zone length (miles). Q is in million gallons per day (MGD). Monthly nutrient loads (kg/month) are Q x C x 8.342 x 30.5 / 2.2, where C is the TN or TP concentration in mg/L. Monthly hydrologic load (m³/month) is Q x 3785 x 30.5. Transmissivity and flow zone length are fixed constants per segment from Zarbock et al. (1994). Hydraulic gradients are season-specific: months 1-6 and 11-12 are dry season; months 7-10 are wet season. Lower Tampa Bay and Remainder Lower Tampa Bay have zero gradient in the dry season and Boca Ciega Bay has zero gradient in both seasons.
Surficial and intermediate aquifers: Loads are fixed monthly constants per segment derived from 1995-1998 (surficial) and 1999-2003 (intermediate) SWFWMD monitoring data. These values have not changed since the original analysis.
Floridan aquifer concentrations
Floridan aquifer TN and TP concentrations (mg/L) can be obtained from
the Water Atlas API using
util_gw_getwq(). The default stations are 18340 (CR 581
North Fldn) and 18965 (SR 52 and CR 581 Deep), the two Pasco County
Floridan aquifer monitoring wells used in the 2022-2024 loading
analysis. Old Tampa Bay uses the first station mean only and
Hillsborough Bay uses the arithmetic mean of both station means. The
rest of the bay segments retain fixed historical values from the
1995-1998 SWFWMD analysis that have been used unchanged in every loading
cycle through 2021.
# Requires internet access; retrieves Floridan aquifer concentrations
wqdat <- util_gw_getwq()When wqdat = NULL (the default in
anlz_gw()), hardcoded concentrations from the 2022-2024
analysis are used directly.
Estimating groundwater loads
anlz_gw() requires only a year range. Hardcoded 2021
FDEP potentiometric surface gradients are used for all years because
updated contours were not available when the 2022-2024 analysis was
run.
gw <- anlz_gw(yrrng = c(2022, 2024))
head(gw)
#> Year Month source segment tn_load tp_load hy_load
#> 1 2022 1 GW Boca Ciega Bay 0.0004188783 0.003957298 0.0132126
#> 2 2022 2 GW Boca Ciega Bay 0.0004188783 0.003957298 0.0132126
#> 3 2022 3 GW Boca Ciega Bay 0.0004188783 0.003957298 0.0132126
#> 4 2022 4 GW Boca Ciega Bay 0.0004188783 0.003957298 0.0132126
#> 5 2022 5 GW Boca Ciega Bay 0.0004188783 0.003957298 0.0132126
#> 6 2022 6 GW Boca Ciega Bay 0.0004188783 0.003957298 0.0132126Load columns are in tons/month and hy_load is in million
m³/month.
To pass concentrations retrieved from the API:
# Requires internet access
wqdat <- util_gw_getwq()
gw_api <- anlz_gw(yrrng = c(2022, 2024), wqdat = wqdat)Temporal summary
Setting summtime = 'year' sums monthly loads to annual
totals. The Month column is dropped.
anlz_gw(yrrng = c(2022, 2024), summtime = 'year')
#> Year source segment tn_load tp_load hy_load
#> 1 2022 GW Boca Ciega Bay 0.00502654 0.04748757 0.1585512
#> 2 2023 GW Boca Ciega Bay 0.00502654 0.04748757 0.1585512
#> 3 2024 GW Boca Ciega Bay 0.00502654 0.04748757 0.1585512
#> 4 2022 GW Hillsborough Bay 20.72632859 2.46652041 73.9028084
#> 5 2023 GW Hillsborough Bay 20.72632859 2.46652041 73.9028084
#> 6 2024 GW Hillsborough Bay 20.72632859 2.46652041 73.9028084
#> 7 2022 GW Lower Tampa Bay 0.10948950 0.62279120 3.8203550
#> 8 2023 GW Lower Tampa Bay 0.10948950 0.62279120 3.8203550
#> 9 2024 GW Lower Tampa Bay 0.10948950 0.62279120 3.8203550
#> 10 2022 GW Manatee River 0.10249411 0.50923100 3.5031130
#> 11 2023 GW Manatee River 0.10249411 0.50923100 3.5031130
#> 12 2024 GW Manatee River 0.10249411 0.50923100 3.5031130
#> 13 2022 GW Middle Tampa Bay 0.28633333 1.62254143 9.9954764
#> 14 2023 GW Middle Tampa Bay 0.28633333 1.62254143 9.9954764
#> 15 2024 GW Middle Tampa Bay 0.28633333 1.62254143 9.9954764
#> 16 2022 GW Old Tampa Bay 6.58537094 1.95697341 60.1804539
#> 17 2023 GW Old Tampa Bay 6.58537094 1.95697341 60.1804539
#> 18 2024 GW Old Tampa Bay 6.58537094 1.95697341 60.1804539
#> 19 2022 GW Terra Ceia Bay 0.01894529 0.10028212 0.6552311
#> 20 2023 GW Terra Ceia Bay 0.01894529 0.10028212 0.6552311
#> 21 2024 GW Terra Ceia Bay 0.01894529 0.10028212 0.6552311