SWAT-predicted influence of different landscape and cropping system alterations on phosphorus mobility within the Pike River watershed of south-western Québec

Abstract

. 2007. SWAT-predicted influence of different landscape and cropping system alterations on phosphorus mobility within the Pike River watershed of south-western Québec. Can. J. Soil Sci. 87: [329][330][331][332][333][334][335][336][337][338][339][340][341][342][343][344]. An agreement between the governments of the province of Québec and the State of Vermont calls for a 41% decrease in phosphorus (P) loads reaching Missisquoi Bay, the northern portion of Lake Champlain. The agreement particularly targets the agricultural sector, since 80% of non-point source P inputs to the bay are associated with cultivated lands. In order to identify sustainable cropping practices likely to help meet the target P loads, the SWAT (soil and water assessment tool) model was employed to assess hydrological performance, erosion processes and P mobility on the bay's principal Québec P contributing tributary, the 630 km 2 Pike River watershed. Strong in-watershed spatial clustering of vulnerability to non-point source exports highlights the need for targeted implementation of sustainable agricultural practices and soil conservation works to derive the reduction in P loads. Planting cover crops over the 10% most vulnerable lands would result in roughly a 21% drop in overall P exports at the watershed outlet, whereas the same 10% randomly distributed over the watershed would only contribute to a 6% drop in P exports. The study of different field-scale management scenarios indicated that achieving the targeted 41% reduction in P exports would require the widespread (half the land devoted to annual crops) implementation of sustainable cropping practices, and the conversion of a specific 10% of the territory to either cover crops or permanent prairie land. Meeting the P target-loads would require additional investments in the protection of floodplains and riparian strips, the targeted construction of runoff-control structures, and the rapid soil incorporation of manures on lands dedicated to annual crops.Key words: Soil and water assessment tool, modelling, sediment, phosphorus, cropping system, scenario, best agricultural management practices Michaud, A. R., Beaudin, I., Deslandes, J., Bonn, F. et Madramootoo, C. A. 2007. Modélisation de l'influence du paysage et des systèmes culturaux alternatifs sur la mobilité du phosphore dans le basin versant de la rivière aux Brochets, Québec. Can. J. Soil Sci. 87: 329-344. La réduction de 41 % des flux de phosphore à la baie Missisquoi, portion septentrionale du lac Champlain, a fait l'objet d'une entente entre les gouvernements de la province de Québec et de l'état du Vermont. L'entente interpelle particulièrement le secteur agricole, puisque 80 % des apports diffus de phosphore (P) atteignant la baie y originent. À l'aide de SWAT (Soil and Water Assessment Tool), une modélisation du fonctionnement hydrologique, des processus d'érosion et de la mobilité du P a été réalisée à l'échelle du bassin versant de la rivière aux Brochets (630 km 2 ), principal contributeur de P à la baie en territoire québ...

Simulated impacts of climate change and agricultural land use change on surface water quality with and without adaptation management strategies

“…In a previous study , SWAT was used as a decision support system to define optimal land uses and field management changes that would provide at least a 41% reduction in TP loads into the Missisquoi Bay, to achieve acceptable water quality at the watershed outlet. The aim of the STRAT scenario was to replicate the same management strategies that were most effective in the Michaud et al (2007) study, but this time using SWAT with the future climate and agricultural land use changes. The following adaptation strategies were implemented in the STRAT scenario based on reconstituting the major elements of scenario #21 in Michaud et al (2007):…”

“…The aim of the STRAT scenario was to replicate the same management strategies that were most effective in the Michaud et al (2007) study, but this time using SWAT with the future climate and agricultural land use changes. The following adaptation strategies were implemented in the STRAT scenario based on reconstituting the major elements of scenario #21 in Michaud et al (2007):…”

Impacts of climate change on nutrient losses from the Pike River watershed of southern Québec

“…Intensive animal production is commonly practiced within the municipalities of the Missisquoi and Pike River watersheds with 38 867, 40 357 and, 37 530 animal units in the years 1996respectively (MDDEP 2007. The watershed has been extensively described in previous studies Michaud et al 2007). …”

“…Organic and inorganic fertilizer applications were kept as originally set by Deslandes et al (2007) and Michaud et al (2007). The methodology used to parameterize individual HRUs' nutrient inputs and crop uptakes has been initially developed by Deslandes et al (2004) (2008) and temporal distribution of rainfall events.…”

Risk aversion and willingness to pay for water quality: The case of non-farm rural residents

“…13 Taxpayers' costs are expressed in dollars per taxpayer, but in our instructions to respondents it was stated that a $2 contribution would amount to a $12 million investment in water quality. 14 Percentage reductions have been used as public policy targets by the Quebec and Vermont governments and they have also been used to describe BMP performance by hydrologists (Michaud et al, 2007). Percentages were used to portray water quality improvements because they are easy to understand by respondents who had to evaluate several attribute trade-offs embodied in the choice sets.…”