Integrated Land and Water Scenarios of the Raisin River Watershed Using the SWAT Model

This paper investigates the linkage between Canada's National Agri-Environmental Standards Initiative (NAESI) Biodiversity and Water themes by studying how patterns in terrestrial habitat, generated through land cover scenario modelling, influence water quality and quantity in the Raisin River watershed in southeastern Ontario. NAESI developed nonregulatory performance standards that define ideal and achievable levels of environmental quality. The indicators used to investigate the scenario risks included sediment and nutrient concentrations. The SWAT (Soil and Water Assessment Tool)-2005 model was calibrated and validated from 1985 to 2006 for current land cover and five other scenarios: potential natural vegetation (PNV); high biodiversity conservation (HBC); moderate biodiversity conservation; agricultural intensification with limited application of conservation direction; and agricultural intensification with no consideration of conservation direction (ANC). Scenario comparisons are provided for the average annual flow, and concentrations of total suspended sediment (TSS), total nitrogen, and total phosphorus for five watershed locations. The PNV scenario predicted the lowest total flows, and sediment and nutrient concentrations, and the ANC scenario predicted the highest sediment and nutrient concentrations. The SWAT median values for the HBC, "Current," and ANC scenarios at the outlet all exceeded the Ideal Performance Standards, except for the median TSS concentration of the HBC scenario.

Overview of Impacts of Recent Land and Channel Changes in Eastern Ontario

Recent land and channel changes on the Raisin River watershed in eastern Ontario altered the hydrological processes of the water cycle in a context of climate fluctuations. In particular, the development of agriculture faced two major obstacles in the area: a high water table and too long flood duration. Land transformations were intended to solve those problems and were relatively successful, though in accelerating the flow of land water toward the stream, the water balance was modified, which in turn changed the water quality dynamics. Surface hydrology and water quality of the Raisin River as they appear today are in part the result of past land transformations. Stream water quality restoration should therefore not be addressed alone but be integrated with restoration of hydrological processes at the scale of the watershed, a new necessity in the context of climate warming.