| Title: | Modeling the effects of onsite wastewater treatment systems on nitrate loads using SWAT in an urban watershed of Metropolitan Atlanta |
| Authors: | Hoghooghi, N., D.E. Radcliffe, M.Y. Habteselassie and J. Jeong |
| Year: | 2017 |
| Journal: | Journal of Environmental Quality |
| Volume (Issue): | 46(3) |
| Pages: | 632-640 |
| Article ID: | |
| DOI: | 10.2134/jeq2016.08.0322 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | on-site and/or municipal wastewater systems |
| Secondary Application Category: | nitrogen cycling/loss and transport |
| Watershed Description: | 44 km^2 Big Haynes Creek, located east of the city of Atlanta in Gwinnett County, north central Georgia, U.S. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Onsite wastewater treatment systems (OWTSs) can be a source
of nitrogen (N) pollution in both surface and ground waters.
In metropolitan Atlanta, GA, >26% of homes are on OWTSs. In
a previous article, we used the Soil Water Assessment Tool to
model the effect of OWTSs on stream flow in the Big Haynes
Creek Watershed in metropolitan Atlanta. The objective of this
study was to estimate the effect of OWTSs, including failing
systems, on nitrate as N (NO3–N) load in the same watershed. Big
Haynes Creek has a drainage area of 44 km2 with mainly urban
land use (67%), and most of the homes use OWTSs. A USGS
gauge station where stream flow was measured daily and NO3–N
concentrations were measured monthly was used as the outlet.
The model was simulated for 12 yr. Overall, the model showed
satisfactory daily stream flow and NO3–N loads with Nash–
Sutcliffe coefficients of 0.62 and 0.58 for the calibration period
and 0.67 and 0.33 for the validation period at the outlet of the Big
Haynes Watershed. Onsite wastewater treatment systems caused
an average increase in NO3–N load of 23% at the watershed scale
and 29% at the outlet of a subbasin with the highest density
of OWTSs. Failing OWTSs were estimated to be 1% of the total
systems and did not have a large impact on stream flow or
NO3–N load. The NO3–N load was 74% of the total N load in the
watershed, indicating the important effect of OWTSs on stream
loads in this urban watershed. |
| Language: | English |
| Keywords: | |