Skip to contents

Estimated non-point source (NPS) ungaged loads

Source: R/anlz_nps_ungaged.R
anlz_nps_ungaged.Rd

Estimated non-point source (NPS) ungaged loads

Usage

anlz_nps_ungaged(
  yrrng = c("2021-01-01", "2023-12-31"),
  tbbase,
  rain,
  lakemanpth,
  tampabypth,
  bellshlpth,
  verbose = TRUE
)

Arguments

yrrng

A vector of two dates in 'YYYY-MM-DD' format, specifying the date range to retrieve flow data. Default is from '2021-01-01' to '2023-12-31'.

tbbase

data frame containing polygon areas for the combined data layer of bay segment, basin, jurisdiction, land use data, and soils, see details

rain

data frame of rainfall data, see details

lakemanpth

character, path to the file containing the Lake Manatee flow data, see details

tampabypth

character, path to the file containing the Tampa Bypass flow data, see details

bellshlpth

character, path to the file containing the Bell shoals data, see details

verbose

logical indicating whether to print verbose output

Value

A data frame with monthly pollutant load estimates containing the following columns:

  • bay_seg: Bay segment identifier (1: Old Tampa Bay, 2: Hillsborough Bay, 3: Middle Tampa Bay, 4: Lower Tampa Bay, 5: Upper Boca Ciega Bay, 6: Terra Ceia Bay, 7: Manatee River, 55: Lower Boca Ciega Bay)

  • basin: Basin identifier (USGS gage number or internal code)

  • yr: Year

  • mo: Month (1-12)

  • clucsid: Consolidated Land Use Classification System ID

  • h2oload: Water load (cubic meters)

  • tnload: Total nitrogen load (kg)

  • tpload: Total phosphorus load (kg)

  • tssload: Total suspended solids load (kg)

  • stnload: Stormwater total nitrogen load (kg)

  • stpload: Stormwater total phosphorus load (kg)

  • stssload: Stormwater total suspended solids load (kg)

  • bodload: Biochemical oxygen demand load (kg)

  • area: Land use area (hectares)

  • bas_area: Total basin area (hectares)

Details

This function estimates pollutant loads from non-point sources in ungaged (unmonitored) basins within the Tampa Bay watershed. The approach combines spatial land use data, rainfall patterns, hydrologic modeling, and empirical relationships to estimate monthly nutrient and sediment loads. Several steps are followed:

  1. Data Preparation: Processes land use data for logistic regression modeling and calculates inverse distance-weighted rainfall data for each sub-basin.

  2. Flow Estimation: Uses a logistic regression model to predict monthly streamflow in ungaged basins based on:

    • Current month rainfall and 2-month lagged rainfall

    • Land use percentages (urban, agriculture, wetlands, forest)

    • Seasonal patterns (wet season: July-October, dry season: November-June)

    • Urban development intensity (Group A: <19% urban, Group B: ≥19% urban)

    • Hydrologic soil group characteristics

  3. Runoff Coefficient Application: Applies land use and soil-specific runoff coefficients to distribute predicted flows across different landscape types within each basin.

  4. Load Calculation: Estimates pollutant loads using Event Mean Concentrations (EMCs) for different land use categories (CLUCSID), calculating:

    • Total Nitrogen (TN) loads

    • Total Phosphorus (TP) loads

    • Total Suspended Solids (TSS) loads

    • Biochemical Oxygen Demand (BOD) loads

    • Stormwater-specific loads (with different EMCs for certain categories)

Spatial Framework:

The analysis uses a nested spatial hierarchy:

  • Bay Segments: Major subdivisions of Tampa Bay (1-7, with 55 for Lower Boca Ciega Bay)

  • Basins: Hydrologic sub-basins, including both USGS gaged and ungaged areas

  • Land Use Polygons: Detailed spatial units combining jurisdiction, land use (FLUCCS codes), and soil characteristics

Flow Prediction Models:

The function uses season- and development-specific regression equations:

  • Separate models for wet vs. dry seasons

  • Separate models for low-development (Group A) vs. high-development (Group B) areas

  • Models account for antecedent moisture conditions through lagged rainfall terms

Load Estimation:

Pollutant loads are calculated as: Load = Flow × EMC × Unit Conversions

Where EMCs vary by land use category (CLUCSID). Special handling is applied for water bodies and certain wetland types (CLUCSIDs 18, 20), which are assigned zero stormwater loads.

Requires the following inputs:

  • tbbase: A data frame containing polygon areas for the combined data layer of bay segment, basin, jurisdiction, land use data, and soils, Stored as tbbase or created (takes an hour or so) with util_nps_tbbase.

  • rain: A data frame of rainfall data. See rain.

  • lakemanpth: character, path to the file containing the Lake Manatee flow data. See util_nps_getextflow.

  • tampabypth: character, path to the file containing the Tampa Bypass flow data. See util_nps_getextflow.

  • bellshlpth: character, path to the file containing the Bell shoals data. See util_nps_getextflow.

USGS gaged flows are also used, as returned by util_nps_getusgsflow and combined with the external flow data using util_nps_getextflow and util_nps_getflow.

Examples

if (FALSE) { # \dontrun{
# external flow sources
lakemanpth <- system.file('extdata/nps_extflow_lakemanatee.xlsx', package = 'tbeploads')
tampabypth <- system.file('extdata/nps_extflow_tampabypass.xlsx', package = 'tbeploads')
bellshlpth <- system.file('extdata/nps_extflow_bellshoals.xls', package = 'tbeploads')

anlz_nps_ungaged(yrrng = c('2021-01-01', '2023-12-31'), tbbase,
   rain, lakemanpth, tampabypth, bellshlpth)
} # }