Airborne LIDAR Technology for Sustainable Watershed Management: Red River Basin

Southern Manitoba has a long history of flooding events which has led to significant damages in the region over the years. The Red River Valley (RRV) is a disaster hot spot in the United States and a multi-million dollar floodway was built to protect the City of Winnipeg from floodwaters in Canada (see Figure 1). The spring melt of 2011 brought with it simultaneous flooding events in most of Southern Manitoba (Public Safety Canada 2013). The Assiniboine and Souris River Basins which typically do not have excess floodwaters were also gravely affected in 2011. Water quality also suffers across Southern Manitoba as excess nutrients primarily entrained during the spring snow melt have led to the eutrophication of many water bodies including Lake Winnipeg which has become the largest eutrophic large lake in the world (Lake Winnipeg Foundation, Undated).

A better understanding of the hydrodynamic behavior of Southern Manitoba is required to circumvent these problems. High resolution elevation data is fundamental to understanding the hydrology of a given landscape. Southern Manitoba’s flat and near-uniform topography requires elevation data of the greatest accuracy and precision to determine where and how fast the water will flow on the landscape. Following the 1997 flood in the RRV, which devastated Grand Forks and prompted emergency flood mitigation measures in Winnipeg, a number of efforts were made to collect high resolution elevation data for flood mitigation purposes. LIDAR was collected along the Canadian portion of the RRV in the early 2000s and additional areas were acquired subsequently. Recognizing the importance of adequate elevation data across the basin, the International Water Institute in North Dakota coordinated the collection of LIDAR data for the entire portion of RRB in the United States (International Water Institute, Undated).

The LIDAR data sets collected on both sides of the border have been invaluable as it has been used for a number of land use planning and watershed management applications. It is currently being used in the RRB primarily for flood prevention initiatives but also for water and nutrient management efforts.

The LIDAR data that has been collected within the RRB has been used to model the hydrology of the river’s main stem during spring runoff using the MIKE-11 modeling platform. The International Joint Commission recently used LIDAR and the Telemac-2D hydrodynamic model to simulate the 2006 flood on the Pembina River tracking where the water flows on the landscape (Bell, 2011). High resolution elevation data is being used to plan a number of flood mitigation infrastructure investments such as community ring dykes and water impoundments (Glazewski et al. 2011). The International Water Institute and the Minnesota Centre for Environmental Policy Advocacy are using LIDAR data to identify adequate water retention locations and wetland restoration initiatives.

LIDAR data is also being used for water quality and nutrient management projects. Agriculture and Agri-Food Canada and the LaSalle Redboine Conservation District have acquired LIDAR data to model nutrient flows from the LaSalle watershed using Soil and Water Assessment Tool modeling. This will provide insights for developing effective programs and practices that could improve water quality.

Despite its value, high resolution elevation data has not been collected for all of Southern Manitoba. High acquisition costs remain a significant obstacle to its collection. Consequently, comprehensive and accurate hydrodynamic modeling for Southern Manitoba without sweeping assumptions remains impossible.