Thursday, May 21, 2009 - 9:00 AM
536

Estimation of achievable performance standards for nutrients and sediments in streams draining agricultural watersheds through scenario-based modeling

Glenn A. Benoy1, Qi Yang2, Isaac Wong3, Fanrui Meng2, Bill Booty3, Joseph M. Culp4, and Patricia Chambers3. (1) Environment Canada and Agriculture and Agri-Food Canada, 850 Lincoln Road, PO Box 20280, Fredericton, NB E3B 4Z7, Canada, (2) Forestry and Environmental Management, University of New Brunswick, Fredericton, NB E3B 6C2, Canada, (3) Environment Canada, 867 Lakeshore Road, Burlington, ON L7R 4A6, Canada, (4) University of New Brunswick, Environment Canada and Canadian Rivers Institute, 10 Bailey Drive, PO Box 45111, Fredericton, NB NB E3B 6E1, Canada

For Canada’s National Agri-Environmental Standards Initiative (NAESI), SWAT model was used to develop achievable performance standards (APS) for nutrients and suspended sediments (TSS) in streams of two agricultural watersheds. For the Black Brook watershed (BBW) in New Brunswick, simulations of BMP implementation (including diversion terraces, crop rotation, tillage practices, and fertilizer application rates) forecast reductions in average concentrations of TSS by 92%.  The provisional average daily APS value for BBW was 56.7 mg/L for TSS.  For nutrients, provisional APS for average daily concentrations of nitrate-N and soluble P were 2.13 and 0.010 mg/L, respectively.  Compared to current conditions, the impacts of these BMPs on water quality are greater for sediments and soluble P than nitrate-N.  For the Raisin River watershed (RRW) in Ontario, simulations of “ideal” and realistic biodiversity conservation scenarios (including changes to extent of forest and wetland coverage, and buffer zone widths) forecast that TSS would be reduced by 12.8% and 2.6%, respectively, in comparison with current conditions, and that APS levels of 1.78 mg/L for TN and 0.031 mg/L for TP could be achieved.  APS for both watersheds are likely to change as additional BMPs are incorporated into the modeling framework (i.e., grassed waterways and riparian management for BBW, and tile drainage management and restriction of livestock access for RRW).


Web Page: agri-environmental standards, beneficial management practices, scenario-based modeling