Environmental Management

, Volume 47, Issue 3, pp 398-409

First online:

Nutrient Response Modeling in Falls of the Neuse Reservoir

  • Jing LinAffiliated withModeling and TMDL Unit, Department of Environment and Natural Resources, North Carolina Division of Water Quality-PlanningDepartment of Marine, Earth, and Atmospheric Sciences, North Carolina State University Email author 
  • , Jie LiAffiliated withCollege of Ocean and Meteorology, Guangdong Ocean UniversityDepartment of Marine, Earth, and Atmospheric Sciences, North Carolina State University

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In order to study system responses of Falls of the Neuse Reservoir (Falls Lake) to varied nutrient loadings, a coupled three-dimensional hydrodynamic and eutrophication model was applied. The model was calibrated using 2005 and 2006 intensive survey data, and validated using 2007 survey data. Compared with historical hydrological records, 2005 and 2007 were considered as dry years and 2006 was recognized as a normal year. Relatively higher nutrient fluxes from the sediment were specified for dry year model simulations. The differences were probably due to longer residence time and hence higher nutrient retention rate during dry years in Falls Lake. During the normal year of 2006, approximately 70% of total nitrogen (TN) and 80% of total phosphorus (TP) were delivered from the tributaries; about 20% (TN and TP) were from the sediment bottom. During the dry years of 2005 and 2007, the amount of TN released from sediment was equivalent to that introduced from the tributaries, indicating the critical role of nutrient recycling within the system in dry years. The model results also suggest that both nitrogen and phosphorus are limiting phytoplankton growth in Falls Lake. In the upper part of the lake where high turbidity was observed, nitrogen limitation appeared to dominate. Scenario model runs also suggest that great nutrient loading reductions are needed for Falls Lake to meet the water quality standard.


Nutrients Eutrophication Water quality modeling Falls Lake Benthic flux