SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Modeling mineral nitrogen export from a forest terrestrial ecosystem to streams 
Authors:Li, X., R.B. Ambrose and R. Araujo 
Journal:Transactions of the ASABE 
Volume (Issue):47(3) 
Article ID: 
URL (non-DOI journals): 
Broad Application Category:pollutant only 
Primary Application Category:model and/or data interface 
Secondary Application Category:nitrogen cycling/loss and transport 
Watershed Description:31.6 km^2 Hubbard Brook Experimental Forest drainage area, located in central New Hampshire, U.S. 
Calibration Summary: 
Validation Summary: 
General Comments:The DAYCENT model was used to estimate landscape level nitrogen cycling and losses. Transport of mineral N exported from subwatersheds was simulated with SWAT to the watershed outlet. 
Abstract:Terrestrial ecosystems are major sources of N pollution to aquatic ecosystems. Predicting N export to streams is a critical goal of nonpoint−source modeling. This study was conducted to assess the effect of terrestrial N cycling on stream N export using long−term monitoring data from Hubbard Brook Experimental Forest (HBEF) in New Hampshire. The field−scale DAYCENT model was used to quantify N pools and long−term annual streamflow and mineral N export for six subwatersheds at the HBEF. By combining DAYCENT with the Soil and Water Assessment Tool (SWAT) watershed model, mineral N export simulations were extended to the watershed scale. Our study indicated that only 13% of external N input was exported to streams during 1951−2000 at HBEF. As much as 4763 kg/ha of N was stored in forest litter, soil organic matter (SOM), and living plant biomass. Net N mineralization of SOM and forest litter contributed 93% of total available N for export within the HBEF ecosystem. The Nash−Sutcliffe coefficient (Ens) evaluating model performance of DAYCENT at six subwatersheds ranged from 0.72 to 0.82 for simulating annual streamflow (1964−2000) and from 0.48 to 0.67 for annual mineral N export (1971−1995), indicating reasonable simulated values. DAYCENT successfully predicted the effect of ecosystem disturbance such as forest cut and insect invasion on stream mineral N export. The watershed−scale simulation suggested that soil spatial variability affects stream N export in addition to the accepted controls of land cover, external N input, climate, and ecosystem disturbance. 
Keywords:Biogeochemical processes, Hardwood forest, Modeling, Nitrogen export, Nonpoint-source pollution, Soil organic matter, Terrestrial ecosystem, Water quality.