Modelling Nitrogen Transport and Removal in Wetlands Using SWAT+

Wetlands capability to remove nitrogen from water is an essential ecosystem service needed to improve water quality. Quantifying nitrogen removal and monitoring at watershed scale is an expensive and time consuming task that may not be feasible everywhere. For that reason modelling the formation of wetlands across the floodplain of a watershed is a growing interest among scientist and decision makers. The revised version of the Soil and Water Assessment Tool (SWAT) called SWAT+ implements with ease the hydrological connectivity among different hydrologic spatial units. Improving from its predecessor, the connectivity between highlands and wetlands is a much more intuitive process, facilitating its use for the common user, without the need to change its base code. This study explores the runoff routing capabilities of SWAT+ by creating the wetland floodplain in the Little River Experimental Watershed located in Tifton-Georgia. Nitrogen concentrations and loads are being modelled and compared to in stream chemical data and removal percentages due to denitrification are simulated. Results show the effects of the implementation of the wetlands on the water and nitrogen balance of the area as well as its effect on the simulation of the waterflow.