EV1-237
mmacrae@uwaterloo.ca
Merrin started in the Department in 2006 and has research interests in the linkages between hydroclimatology, biogeochemical cycling and surface-water chemistry in both natural and impacted systems under variable climatic regimes and following disturbance or land use change. Her work is largely in agricultural watersheds and wetland ecosystems
Key Areas of Graduate Supervision
biogeochemistry, hydrology, wetland science, agricultural water quality, agricultural tile drainage, nutrients
Recent Courses Taught
GEOG 102: Global Environmental Systems: Processes and Change
GEOG 303: Physical Hydrology
GEOG 407: Environmental Hydrology
GEOG 640: Foundations in Environmental Science
Research Interests
Professor Macrae’s research explores the individual and combined impacts of hydroclimatology and land use change on water quality in disturbed landscapes. The vast majority of her work has been done in agricultural systems, although she applies this general concept across different landscapes such as disturbed wetlands and surface water bodies. Her recent work has focused on (1) understanding the role of assisted or modified drainage on water quantity and quality in agricultural landscapes; (2) understanding differences in hydrological and biogeochemical processes between cold and warm regions, and (3) development of targeted conservation strategies based on geographic regions and landscape types to improve water quality.
Selected Recent Publications (for full list, see research page)
*denotes MM HQP; ** denotes other HQP
- Gospodyn*, L., Jarvie, H.P., Williams, M., Plach, J.M., Macrae, M.L. (2026) Separating flow components in tile drainage and streamflow in a headwater agricultural catchment. Journal of Hydrology: Regional Studies 63: 103081.
- Macrae, M.L., Kleinman, P.J., Osmond, D., Shober, A. and Nelson, N., (2025) The importance of consensus science to managing phosphorus in the environment: SERA‐17 and the legacy of Andrew Sharpley. Journal of Environmental Quality, 54(4): 798-806.
- Shober, A.L, Simpson, Z.P., Jarvie, H.P., Macrae, M.L., Kleinman, P.J.A., Haygarth, P.M., Kulesza, S., Gatiboni, L., Davies, J. (2025) Towards a transdisciplinary and unifying definition of legacy phosphorus. Journal of Environmental Quality 54 (4), 882-892.
- Hanke*, K., Singh, N.K., Basu, N.B., Michaud, A., Yang, W. and Macrae, M.L., 2024. Going underground: Changing climate and flow seasonality may increase subsurface flow contribution and modify dissolved nutrient export from agricultural catchments. Journal of Great Lakes Research: 102452.
- Noyes*, I., Koiter, A., Jarvie, H.P., Plach*, J.M., Lobb, D.A., Glasauer, S. and Macrae, M.L., 2024. Potential phosphorus mobilization from riparian vegetation following freezing. Journal of Environmental Management, 370: 122710.
- Kompanizare*, M., Costa, D. Macrae, ML, Pomeroy, J, Petrone RM. (2024) Developing a tile drainage module for Cold Regions Hydrological Model: Lessons from a farm in Southern Ontario, Canada. Hydrology and Earth System Sciences, 28(13): 2785-2807.
- Macrae, ML, Plach*, JM, Carlow*, R, Little, C, Jarvie, H, McKague, K, Pluer*, W, Joosse, M. (2023). Trade-offs in nutrient and sediment losses in tile drainage from no-till versus conventional conservation till cropping systems. Journal of Environmental Quality 52(5): 1011-1023.
- Carlow*, R., Plach*, J.M., Pluer*, W.T., Lam*., W.V., Kompanizare*, M., Brunke, R., McKague, K., Jarvie, H.P., and Macrae, M.L. (2023) Can surface filters at the edge-of-field reduce phosphorus losses from agricultural fields that already use multiple conservation practices? Agricultural Water Management 284: 108362.
- Kokulan*, V., Macrae, M.L., Plach*, J.M., Ali, G.A., Morison*, M., and Lobb, D.A. (2023) Phosphorus dynamics in surface runoff during overbank flooding of field-edge and ditches in vertisolic clay agricultural land in the Red River Valley. Canadian Water Resources Journal 48(3): 1-13.
- Plach*, J.M., Macrae, M.L., Wilson, H.F., Costa, D., Kokulan, V., Lobb, D.A. and King, K.W., 2022. Influence of climate, topography, and soil type on soil extractable phosphorus in croplands of northern glacial‐derived landscapes. Journal of Environmental Quality 51(4): 731-744.
- Price*, D., Plach*, J.M., Jarvie, H.P., and Macrae, M.L. 2021. Bunker silo runoff discharged via a riparian zone: contributions to watershed phosphorus loads under varying flow conditions. Journal of Great Lakes Research 47(5), 1296-1304
- Macrae, M.L., Jarvie, H., Brouwer, R., Gunn, G., Reid, K., Joosse, P., King, K., Kleinman, P.J., Smith, D., Williams, M. and Zonitzer, M. (2021) One Size Does Not Fit All: Towards Regional Conservation Practice Guidance to Reduce Phosphorus Loss Risk in the Lake Erie Watershed. Journal of Environmental Quality 50(3): 529-546.