Disentangling Impacts of Climate & Land Use Change on Quantity & Quality of River Flows in Southern Ontario Trevor Dickinson Ramesh Rudra University of Guelph
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Climate change has lowered spring flood risks in Ontario rural watersheds due to higher temperatures, lower snowpack and lower spring runoff volumes. There have been no changes in precipitation affecting runoff volumes, and observed increases in summer runoff are due to urbanization, not climate change effects. Dr. Dickinson and Dr Rudra rightly describe the need for 'disentangling', given the prevalent approach of ignoring hydrologic changes in watersheds and incorrectly linking flood events on climate change and extreme rainfall and precipitation changes that have not been observed in local and regional data. These findings on annual and seasonal patterns complement work by Environment and Climate Change Canada on short duration rainfall that shows no detectable trend in rainfall intensities in the Engineering Climate Datasets contrary to insurance industry statements: https://www.slideshare.net/RobertMuir3/storm-intensity-not-increasing-factual-review-of-engineering-datasets
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Disentangling Impacts of Climate & Land Use Change on Quantity & Quality of River Flows in Southern Ontario Trevor Dickinson Ramesh Rudra University of Guelph
- 1. Disentangling Impacts of Climate & Land Use Changes on the Quantity & Quality of River Flows in Southern Ontario by Trevor Dickinson & Ramesh Rudra, Water Resources Engineering University of Guelph
- 2. Acknowledgements Agencies NSERC, OMAF & Environment Canada Personnel Barry Smith - Retired Program Manager, Water Survey of Canada Golmar Golmohammadi – Post Doctoral Research Fellow Arezoo Amili – Former Graduate Student Akul Bhatt – Undergraduate Student Assistant
- 3. River Flows Have Changed
- 4. 0 20 40 60 80 100 120 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 1916-1925 0 20 40 60 80 100 120 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 2004-2013 Average Monthly Flow Hydrographs For Rural Watersheds like the Moira River at Foxboro: winter flows have increased, spring flows have decreased, & summer flows have remained unchanged.
- 5. 0 1 2 3 4 5 6 7 8 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 2004-2013 0 1 2 3 4 5 6 7 8 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 1916-19251963-1972 Average Monthly Flow Hydrographs For a highly Urbanized Watershed like the Don River at Todmorden: winter flows have increased, spring flows have decreased, & summer flows have greatly increased.
- 6. Monthly & Annual Precipitation has remained unchanged.
- 7. 0 200 400 600 800 1000 1200 1940 1950 1960 1970 1980 1990 2000 2010 AverageAnnualPrecipitation(mm) Nith at New Hamburg Grand at Brantford Cedar Creek at Woodstock Moira near Foxboro Linear (Nith at New Hamburg) Linear (Grand at Brantford) Linear (Cedar Creek at Woodstock) Linear (Cedar Creek at Woodstock) Linear (Moira near Foxboro)
- 8. What’s Going On?! Possible causes of changes in the river flows include: - Changes in Climate, and/or - Changes in Land Use i.e. Urban Development
- 9. How Has Our Climate Changed?
- 10. Temperatures Have Risen - mostly in the Winter
- 12. Changes in Winter Mean Minimum Daily Temperature
- 13. Annual Temperature Trend Slopes
- 14. Rates of Increase in Temperatures Celsius degrees per 100 years Extreme Daily Minimum - 3.5 to 4.0 Mean Daily Minimum - 2.0 Mean Daily - 1.5 Mean Daily Maximum - 0.5 Extreme Daily Maximum - 0 to – 0.5
- 15. So … Temperatures have been increasing somewhat steadily in Ontario, - perhaps for up to and at least 150 years! Winter temperatures have been rising at the greatest rate, suggesting that winter hydrology may have been impacted more than summer hydrology. Temperature Trends
- 16. The Frequency of Frost – Free Days has Increased Exponentially
- 17. Frost-Free Days 020040060080010001200 0 10 20 30 40 50 60 70 80 -25 -20 -15 -10 -5 0 NumberofFrost-FreeDaysperWinter Winter Mean Daily Minimum Temperature (°C) Number of Frost-Free Days versus Mean Daily Minimum Temperature per Winter for 7 Weather Stations WMDMT y = 115.67exp(0.1729x) R² = 0.9496 + 15 days in 60 years + 5 days in 60 years + 1 day in 60 years
- 18. Frost-Free Days As winter mean daily minimum temperatures have been rising steadily, frost-free days have been increasing exponentially. Might snowmelt, which is related to degree-days, also have been increasing exponentially?
- 19. There Has Been a Shift in Winter Precipitation from Snowfall to Rainfall
- 20. Changes in Winter Rainfall
- 22. Changes in Winter Precipitation Total Precipitation Total Precipitation Total Precipitation Snowfall Snowfall Snowfall Rainfall Rainfall Rainfall
- 23. Increased Winter Temperature Increased Number of Frost-Free Days Shift from Snowfall to Rainfall (i.e. fewer Snow Days & Less Snowfall, & more Rainy Days & Winter Rainfall)
- 24. What about Impacts on Snowpacks, Winter Runoff & Infiltration
- 25. Likely Impacts I Rising Winter Temperatures Increasing Number of Frost-Free Days Increased Winter Snowmelt
- 26. Likely Impacts II Increased Winter Snowmelt Increased Winter Rainfall Increased Winter Surface Runoff and/or Increased Winter Infiltration
- 27. More Impacts I Increased Winter Tile Flow Increased Winter Groundwater Recharge Increased Winter Infiltration
- 28. More Impacts II Increased Winter Surface Runoff Increased Winter Tile Flow & Recharge Increased Winter Streamflow
- 30. 0 20 40 60 80 100 120 140 160 Dec Dec Dec Jan Jan Jan Feb Feb Mar Mar Mar Apr Apr May May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Winter Spring Summer Fall Flow(cms) 1916-1925 0 20 40 60 80 100 120 140 160 Dec Dec Dec Jan Jan Jan Feb Feb Mar Mar Mar Apr Apr May May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Winter Spring Summer Fall Flow(cms) 2004-2013 Average Daily Flow Hydrographs Moira River at Foxboro
- 31. Rural Streamflows So … for Ontario Rural Watersheds, changes in winter climate have: - increased winter streamflows and - decreased spring runoff/freshettes.
- 32. Water Quality Impacts What about Water Quality Impacts Are we now seeing more frequent and greater: - Field & Streambank Erosion, - Stream Sediment Loads, and - Nutrient Loads. in rural watersheds during the winter? Have these loads become smaller and less frequent during spring snowmelt events?
- 33. What about Impacts of Urban Development?
- 34. 0 1 2 3 4 5 6 7 8 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 2004-2013 0 1 2 3 4 5 6 7 8 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 1916-19251963-1972 Average Monthly Flow Hydrographs For a highly urbanized basin like the Don River, winter flows have increased & spring flows have decreased likely as a result of both Climate Change & Urban Development. In addition, the summer flows have increased significantly in volume …
- 35. 0 5 10 15 20 25 30 35 Dec Dec Dec Jan Jan Jan Feb Feb Feb Mar Mar Mar Apr Apr May May May Jun Jun Jun Jul Jul Jul Aug Aug Aug Sep Sep Sep Oct Oct Nov Nov Nov Spring Summer Fall Flow(cms) 1915-19251963-1972 0 5 10 15 20 25 30 35 Dec Dec Dec Jan Jan Jan Feb Feb Feb Mar Mar Mar Apr Apr May May May Jun Jun Jun Jul Jul Jul Aug Aug Aug Sep Sep Sep Oct Oct Nov Nov Nov Spring Summer Fall Flow(cms) 2004-2013 Average Daily Flow Hydrographs … and in frequency on the Don River at Todmorden. What’s going on?!
- 36. 0.0 0.2 0.4 0.6 0.8 1.0 April May June July August September October Significant Urbanization (50%) 0.0 0.2 0.4 0.6 0.8 1.0 April May June July August September October Initial Urbanization 0.0 0.2 0.4 0.6 0.8 1.0 April May June July August September October Before Urbanization Runoff Coefficients Meaneventrunoffcoefficient
- 37. Streamflow Volumes So … in Ontario urban watersheds: - urban development has augmented the winter and spring climate change impacts; and - summer flow volumes have increased dramatically, in volume and frequency, these impacts being completely due to urban development.
- 38. Impacts of Urbanization on River Water Quality Are we seeing more frequent flushes and greater volumes of: - streambank erosion - suspended sediment loads - Chlorides and other pollutants - sewage bypasses ???
- 39. Conclusions River flows have changed in Southern Ontario: - in winter and spring, primarily due to climate change; and - during the summer, primarily due to urban development.
- 40. Questions Water Management Questions What do we do about the changes in river flows - in urbanized and urbanizing watersheds? How have these changes modified water quality, and what do we do in that regard?
- 41. Questions ???
- 42. 0 20 40 60 80 100 120 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 1916-1925 0 20 40 60 80 100 120 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 2004-2013 Monthly Average Flow Hydrograph Moira River at Foxboro
- 43. 0 1 2 3 4 5 6 7 8 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 2004-2013 0 1 2 3 4 5 6 7 8 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Winter Spring Summer Fall Flow 1916-19251963-1972 Monthly Average Flow Hydrograph Don River at Todmorden
- 44. 0 20 40 60 80 100 120 140 160 Dec Dec Dec Jan Jan Jan Feb Feb Mar Mar Mar Apr Apr May May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Winter Spring Summer Fall Flow(cms) 1916-1925 0 20 40 60 80 100 120 140 160 Dec Dec Dec Jan Jan Jan Feb Feb Mar Mar Mar Apr Apr May May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Winter Spring Summer Fall Flow(cms) 2004-2013 Daily Average Flow Hydrograph Moira River at Foxboro