Your Link to Muskoka's Water!

Evaluation and application of SWAT model to surface waters in the Muskoka River
Watershed

April James (PI/Nipissing University)
Huaxia Yao (co-PI/Dorset OMOE)
(Post-doctoral fellow unassigned)

SWAT (Soil Water Assessment Tool) is an internationally used model developed to predict the impact of landuse change on water, sediment and chemical yields in large, complex, heterogeneous terrain. It was originally developed for agricultural landscapes but recent applications are expanding the use of SWAT to new landscapes and diverse landuses (including urban, forest, grasslands). It has extensive publicly available documentation, active users groups in Canada and around the world, and it is part of the USA EPA's BASINS (Better Assessment Science Integrating Point and Nonpoint Sources) software system, a multipurpose environmental analysis system.

SWAT is a dynamic, mass balance model that models temporal changes in hydrologic flowpaths, transformation and stores of nutrients on land and in-streams. Our work will focus on evaluating the abilities of SWAT to model the hydrology and water quality within the Muskoka River Watershed. There has been limited application of SWAT on Canadian Shield forested terrain and climate.

The SWAT modeling code offers an ArcGIS interface, facilitating the use of digital landuse, topography and soils data, and is accessible for research-based alternations. The model includes upland processes (e.g snowmelt, evaporation, runoff, interflow, percolation), in-stream processes (e.g. in-stream kinetics), nutrient processes (e.g. N, P pools, crop uptake, degradation) and management activities.

SWAT modeling studies cover the range of scales (e.g. 1 to 5,000 km²) that span the DESC research catchments (e.g. Harp Lake catchment system) to the full extent of the Muskoka River Watershed, and can incorporate the different types of water bodies that are part of this landscape (e.g. reservoirs, wetlands, small lakes, ponds). Long-term yield simulation (e.g. daily, monthly, decades) makes SWAT well suited to modeling scenarios that incorporate stresses from climate and landuse change.

As part of this project, application of SWAT will formally begin in Spring 2013 with the hiring of a 1-year postdoctoral research position. Advertisement for this position will begin in July 2012.

We have reviewed the SWAT literature, its applications across relevant landscapes and landuse, its open-access codes, and possible modifications that may be required for application to the Muskoka River Watershed. We have collected and prepared a case-study field dataset, the Harp Lake catchment system, which will be used for our first trial of SWAT application and modification.

Update - November 2013

 
SWAT (Soil Water Assessment Tool) is an internationally used model developed to predict the impact of landuse change on water, sediment and chemical yields in large, complex,
heterogeneous terrain. Our work will focus on evaluating the abilities of SWAT to model hydrology and water quality within the Muskoka River Watershed.

The Harp Lake Watershed was used as a case-study for the first trial of SWAT. In this preliminary study we asked whether SWAT could provide reasonable and useful representation of hydrologic function for Canadian Shield watersheds. By testing SWAT on the Harp Lake catchment system, this effort was supported by an extensive 30-year dataset, including on-site water and nutrient balances.

We were particularly interested in testing how SWAT was able to model characteristics and streamflow generation processes that are common to the Canadian Shield (Muskoka River Watershed) landscape, including shallow forested soils with high infiltration rates and low bedrock infiltration, that generate little overland flow due to significant macropore and subsurface flow through hillslopes.

As part of this effort, several revisions were made to the SWAT model. Model results of streamflow, lake outflow and snowmelt are encouraging and suggest to us that additional investigation of hydrochemical/nutrient flux modeling, as well as a larger scale application of SWAT-CS in the Muskoka River Watershed will be valuable in further exploring its use as a tool for managing cumulative effects in the Muskoka River Watershed.