Inputs and Selected Outputs Used to Assess Stormwater Quantity and Quality in Selected Urban Watersheds in Hampton Roads, Virginia, 2016 - 2020

Nitrogen (N), phosphorus (P), and total suspended solids (TSS) loads, in Hampton Roads, Virginia stormwater conveyance systems have been calculated using monitoring data from 12 intensively monitored watersheds for the period from water year (October - September) 2016 through 2020. Nutrient and TSS loads were computed using a surrogate (multiple-linear regression) approach with lab analyzed N, P, and TSS samples as the response variable and basic water-quality parameters (e.g. turbidity, specific conductance, water temperature), streamflow, a baseflow separation Boolean term, and time and seasonal terms as predictor (surrogate) variables. Load results represent the mass of N, P, and TSS exported from each of the Hampton Roads watersheds. Coefficients are provided for each unique station-constituent model. Loads are provided for the following constituents: TSS, total N, total P, nitrate plus nitrite, total Kjeldahl N, total organic N, and orthophosphate. Streamflow is an important driver of water-quality conditions; therefore, datasets are provided describing stream flashiness as well as a suite of event-based metrics, which include stormflow volume, peak flow, lag to peak, storm event duration, time to peak, runoff ratio, and rise rate. Streamflows are driven by precipitation patterns; therefore, rainfall data collected at 10 Hampton Roads Sanitation District (HRSD) gages are also provided. These data were used to evaluate rainfall patterns during the study period as well as compute the lag to peak and runoff ratio metrics for each storm event.
This data release contains six comma-delimited (.csv) files and one zip file with corresponding data dictionary files (.csv). 
HRSD.Rain.csv contains 15-minute interval rainfall data collected at 10 precipitation gages operated by the HRSD.
HR_Loads_CalibrationData.csv contains all data used in the calibration of surrogate regression models for the computation of N, P, and TSS loads.
HR_Loads_SurrogateData.csv contains 5-minute interval measurements of streamflow, water-quality parameters, and a Boolean baseflow separation identifier “BASE.” These data were used to compute 5-minute interval measurements of N, P, and TSS loads using surrogate regression models, which were calibrated with the data provided in HR_Loads_CalibrationData.csv. 
Model_Coefficients.csv contains the coefficients for each station-constituent specific model. 
Storm_Events.csv contains an identification number and mean timestamp for each storm extracted using the methods described in Porter, 2022, and seven metrics describing the hydrograph.
RBI.csv contains an average Richards-Baker Flashiness (RBI) index score for 41 streamgaging stations operated by the United States Geological Survey: Virginia and West Virginia Water Science Center. 
UV_Loads.zip contains 12 identically formatted data tables with 5-minute unit value predictions of N, P, and TSS loads from the beginning of water year (October 1 - September 30) 2016 through 2020 at 12 stormwater monitoring stations in the Hampton Roads region of Virginia. 
For each file entity and attributes are described in data.dictionary.csv that shares the same name. The data dictionary file "UV_Loads_Data.dictionary..csv" applies to all .csv files in the UV_Loads.zip. 
A README text file is also attached, which contains descriptions of each data table and supplementary information.

Tags: biota, coastal-plain, hampton-roads, load-analysis, nitrogen, phosphorus, sediment, stormwater, surrogate-regression, total-suspended-solids, urban, usgs-6241a50fd34e915b67e9e5ad, virginia, water-quality
Organization: Department of the Interior