| Title: | Land use change impacts on water quality in three Lake Winnipeg watersheds |
| Authors: | Yang, Q., L.F. Leon, W.G. Booty, I.W. Wong, C. McCrimmon, P. Fong, P. Michiels, J. Vanrobaeys and G. Benoy |
| Year: | 2014 |
| Journal: | Journal of Environmental Quality |
| Volume (Issue): | 43(5) |
| Pages: | 1690-1701 |
| Article ID: | |
| DOI: | 10.2134/jeq2013.06.0234 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | land use change assessment |
| Secondary Application Category: | pollutant cycling/loss and transport |
| Watershed Description: | 2,400 km^2 La Salle River, 1,102 km^2 Boyne River, and 4,000 km^2 Little Saskatchewan River in central Canada |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Lake Winnipeg eutrophication results from excess nutrient loading due to agricultural activities across the
watershed. Estimating non-point source pollution and the mitigation effects of beneficial management
practices (BMP), is an important step in protecting the water quality of streams and receiving waters. Use
of computer models to systematically compare different landscapes and agricultural systems across the
Red-Assiniboine basin has not been attempted at watersheds of this size in Manitoba. In this study the
Soil and Water Assessment Tool (SWAT) was applied and calibrated for three pilot watersheds of the
Lake Winnipeg basin. Monthly flow calibration yielded overall satisfactory Nash-Sutcliffe coefficient of
efficiency (NSE), with values above 0.7 for all simulations. Total phosphorus (TP) calibration NSE
ranged from 0.64 to 0.76; total nitrogen (TN) from 0.22 to 0.75; and total suspended solids (TSS) from
0.29 to 0.68. Based on the assessment of the TP exceedance levels from 1993 to 2007, annual loads were
above proposed objectives for the three watersheds more than half of the time. Four BMPs scenarios
based on land-use changes were studied in the watersheds: (ACHL) annual cropland to hay land; (WR)
wetland restoration; (MACHL) marginal annual cropland conversion to hay land; and (WRMAC) wetland
restoration on marginal cropland. Of all four land use change scenarios, ACHL had the greatest impact:
TSS loads were reduced by 33-65%, TN by 58-82% and TP by 38-72% over the simulation period. By
analyzing unit area and percentage of load reduction, the results indicate that the WR and WRMAC
scenarios had a significant impact on water quality in high loading zones in the three watersheds. Such
reductions of sediment, nitrogen and phosphorus are possible through land use change scenarios,
suggesting that land conservation should be a key component of any Lake Winnipeg restoration strategy. |
| Language: | English |
| Keywords: | |