Evaluation of WARMF model for flow and nitrogen transport in an agricultural watershed under a cold climate.

The Watershed Analysis Risk Management Framework (WARMF) model is adapted to simulate flow and nitrate-N transport in an agricultural watershed in Quebec, Canada. The model was evaluated for the St. Esprit Watershed (24.3 km²), which is a part of the 210 km² St. Esprit river basin, a tributary of the L'Assomption Watershed (4,220 km²). WARMF's hydrologic calibration and validation was performed using data from the gauge station located at the outlet of the watershed. Water-quality data collected were used to guide water quality calibration/validation. Simulations were carried out from 1994 to 1996; data from 1994 and 1995 were used for model calibration and data from 1996 were used for model validation. The model performed reasonably well in simulating the hydrologic response and nitrate losses at the outlet of the watershed. The R² between the observed and simulated monthly stream flow for calibration was 0.92, and that for validation was 0.94. The corresponding coefficients of efficiency (E) were 0.89 and 0.91. The R² and E values for calibration/validation of NO₃^--N loads simulation were 0.89/0.84 and 0.86/0.75, respectively. Thus, the model simulated monthly flow and nitrogen losses with a good degree of accuracy over the entire year. [ABSTRACT FROM AUTHOR]