Research Project Updates

New and ongoing projects in 2023 are funded by MECP, OMAFRA and NSERC, and focus on chloride transport via groundwater pathways to the Great Lakes, nitrate transport under extreme storm events; phosphorous transport in groundwater and streams; and groundwater-tile drain interactions.

Examples of recent projects include the following:


1. Agricultural N loadings to hydrological systems: Assessing the impacts of climate change

  • 2021-2024
  • Funded by OMAFRA (Ontario Agri-Food Innovation Alliance)
  • Theses:
    • Juan Arce-Rodriguez (MASc): in progress
    • Christina Zeuner (PhD): in progress

Project Summary/Update:

Rural watersheds in southern Ontario are experiencing water quantity and quality stress; this will be magnified by climate change. This project addresses climate change resiliency in Ontario’s Agri-Food sector by assessing storm event driven nutrient loadings from agriculture to stressed watersheds. This is accomplished through a field and modelling study using a well-instrumented research site in southwestern Ontario (Lower Whitemans Creek). An integrated (surface and subsurface) hydrological model (SWAT-MODFLOW software) was previously developed to understand long-term source availability for agricultural production enhanced or limited by groundwater. For this new research, N in soils, surface water and groundwater are quantified at the site, for storm events and seasonal variations. The SWAT-MODFLOW model is used to simulate N mobilization and transport in the hydrological system under expected future conditions. Higher intensity storm events, shorter and warmer winters, dryer summers, and more variable inter-year meteorological conditions are considered. In late 2023, most of the field data has been collected, and the numerical modelling is being conducted. 

Field work in 2023 at Lower Whitemans Creek field site

2. Groundwater-surface water interactions and agricultural nutrient transport in a Great Lakes Basin clay plain system

Project Summary/Update:

Non-point source agricultural contamination (phosphorus and nitrogen) is a serious concern for surface and groundwater quality within the Great Lakes Basin (GLB), with severe associated environmental and ecological implications. The roles of groundwater-surface water interactions and movement of stream sediments in nutrient transport in agriculturally-dominated areas are currently not well understood. The purpose of this research is therefore to investigate the spatial and temporal evolution of phosphorus and nitrate in various hydrological pathways and stream sediments in a typical clay plain system in the GLB.

This research aims to use field-based data collection to help to fill the knowledge gaps that exist concerning nutrient transport through the surface water and groundwater interfaces and the hydrogeological processes influencing this transport in clay dominated settings, typical of the GLB. The subsequent research objectives are to:

  1. Characterize the spatial distribution and temporal evolution of P and N in the shallow groundwater/streambank, stream and streambed over multiple growing seasons;

  2. Relate the observed concentrations to watershed characteristics (e.g. land use) and hydrological patterns;

  3. Model the effect of future changes in hydrologic regime and agricultural practice on the spatiotemporal distribution of stream/streambed P; and

  4. Develop a conceptual model of the geological and hydrological factors responsible for the transport and fate of agricultural P and N to GLB tributaries (via groundwater discharge, overland flow, tile flow) in a typical clay plain setting.

Monthly collection of water (groundwater, surface water, tile water, and hyporheic water) and sediments for water quality analyses (primarily phosphorus and nitrogen species) from five study sites throughout the watershed is conducted. Field research (water and sediment sample collection) and mathematical modelling will continue to be performed to investigate contaminant inflows/transport through the groundwater-surface water interface and determine how the contaminated sediments move downstream in order to better understand processes that contribute to contamination of GLB tributaries by nutrients in agricultural subcatchments.

Thus far, project results suggest that tile drainage water and surface runoff are the main transport pathways for agricultural nutrients in the watershed, with varying influence on surface water quality throughout the year. Groundwater is likely not a significant source of nutrients of to the stream due to clay-rich soil and abundant tile drainage systems in the watershed. Instream loading of phosphorus from streambed sediment may have a critical impact on water quality in the summer months. Further monitoring of this nutrient delivery mechanism is essential to understand overall nutrient transport dynamics in the watershed.

Best management practices (BMPs), such as conservation tillage practices, in the watershed have been linked to water quality observations, particularly elevated dissolved phosphorus concentrations, in the stream. Consequently, BMPs in the watershed should be refined to improve water quality in the area.

Provincial agricultural and environment ministries (OMAFRA, MECP) will benefit from the project results for the development of future research directions or policies for water resource protection related to impacts of agricultural practices. Ontario conservation authorities and landowners in the area can integrate the new knowledge in watershed conservation, restoration, and best management practices.


3. Changing agricultural landscapes and groundwater quality in sensitive aquifers

Project Summary/Update:

Groundwater is the main source of drinking water for rural communities and many cities in Ontario (~30% of the total population). Nitrogen use on agricultural lands has been increasing over the past decades for higher crop yields. However, over application of fertilizers can result in leaching (transport) of excess nutrients below the root zone to aquifers. Weather patterns can also impact nutrient fate. A comprehensive understanding of cropping systems and their potential impacts on groundwater quality in various geological conditions is necessary to ensure protection of rural water supplies for agriculture and potable water. Field data were collected from 25 groundwater monitoring locations in southern Ontario (Acton, Guelph, and Norfolk County).  Groundwater quality was investigated bimonthly since June 2014 in different groundwater settings (sandy aquifers and fractured bedrock aquifers) under different land uses. The collected samples were analyzed for numerous parameters such as pH, electrical conductivity, dissolved oxygen, redox potential, nitrate, chloride, sulphate, dissolved organic carbon, and isotopes of hydrogen, oxygen and nitrogen. Nitrate concentrations varied with time, depth and location. Each of the three research sites displayed different trends. The Guelph site experienced peaks in nitrate concentrations in spring 2016 after a drought period (summer 2015). The Norfolk site displayed concentrations which align with what is expected from a continuous nitrate source, although certain wells had concentration peaks like the Guelph site. The Acton site experienced consistent nitrate concentrations which did not vary significantly. Evidence from groundwater geochemical analyses suggests that denitrification may be occurring at some of the deeper monitoring wells. A vadose zone model (RZWQM) that simulates both vertical water flow and nitrogen losses in the shallow subsurface was used to quantify the movement of nitrate from different crop types through the unsaturated soil zone to groundwater. Suction-type lysimeters were installed at 40 cm depth in different cropping systems to quantify the nitrate infiltrating from fields into the subsurface (June-September 2015). The RZWQM results produced higher shallow nitrate in Norfolk County compared to the other two sites in similar crop types. The vadose zone concentrations were used as input to the groundwater modelling. HydroGeoSphere software was used for the groundwater modelling to quantify groundwater nitrate, focusing on Norfolk and Guelph. Predictive climate and land use scenarios were evaluated following model calibration. Three climate change scenarios were selected based on their extreme conditions. Three land use scenarios were selected (continuous corn, corn-soybeans rotation, corn-soybeans-winter wheat-red clover). A decreasing groundwater elevation trend yielded from the climate change modelling. Nitrate concentrations are also lower in the future, likely due to changes in groundwater recharge. The continuous corn scenario produced much higher nitrate concentrations compared to the other two land use scenarios. Future extreme climate conditions combined with continuous corn can put an aquifer at risk of nitrate contamination. The BMP scenario performed better regarding future nitrate concentrations; it is recommended that farmers adopt BMPs to avoid the nitrate contamination of groundwater and also increase the farm productivity considering future potential climate conditions. 
Monitoring wells in Norfolk County
Monitoring wells in Norfolk County

4. Impacts of alkaline stabilized biosolids application on fate and transport of emerging substances of concern in agricultural soils, plant biomass and drainage water

5. Improving crystalline bedrock aquifer conceptual models using novel discrete fracture network methods

6. Source water protection planning for First Nations communities

7. Groundwater use for agricultural production - current water budget and expected trends under climate change

8. Presence and fate of neonicotinoids in groundwater resources in Ontario