Therefore we isolated a submodel that in addition to hydrology represented the nitrogen dynamics, referred to here as the Water Quality submodel. Calibration tests were carried out, similar to the ones performed for the hydrologic model alone. Unfortunately the data available for dissolved nitrogen is mostly limited to observations of NO3 content in the estuarine part of the Patuxent river. The northern-most point in that data set is provided by the USGS National Stream WQN at Bowie. The calibration was performed for this station and then for the full watershed.
Calibration results for the spatial water quality model.
After the initial adjustment period, the model results were in quite good agreement with the data.