Drought, Climate Variability and Water Resources in Western Canada

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1 Drought, Climate Variability and Water Resources in Western Canada J.W. Pomeroy, K.R. Shook, R.N. Armstrong, X. Fang Centre for Hydrology University of Saskatchewan, Saskatoon, Canada

2 Canadian Rocky Mountains are the Headwaters Rocky Mountains for much of Canadian Prairies North America

3 Canadian Rocky Mountains Cold alpine and sub-alpine climate

4 Rivers Draining the Rocky Mountains Supply Prairie Cities and Irrigation

Canadian Prairie Agriculture: mostly dryland grain farming & pasture Cold, continental, semi-arid climate Precipitation on average 350 mm Grain Growing

5 Canadian Prairie Agriculture: mostly dryland grain farming & pasture Cold, continental, semi-arid climate Precipitation on average 350 mm Grain Growing 125 mm soil water reserves needed from snowmelt 175 mm spring rainfall needed Roughly 300 kg/ha increased wheat yield for each extra 25 mm of water added

Canadian Prairie Drought of 1999-2004 Most Expensive Natural Disaster in Canadian History $5.8 billion decline in GDP 2001-2002 $3.

6 Canadian Prairie Drought of Most Expensive Natural Disaster in Canadian History $5.8 billion decline in GDP $3.6 billion drop in agricultural production, ,000 jobs lost British Columbia & Alberta forest fires Saskatchewan dust storms

7 OBJECTIVE OF DRI the Drought Research Initiative To better understand the physical characteristics of and processes influencing Canadian Prairie droughts, and to contribute to their better prediction, through a focus on the recent severe drought that began in

8 DRI THEMES 1. Quantify the physical features, flows of water and energy into and out of the region, and storage and redistribution within the region 2. Improve the understanding of processes and feedbacks governing the formation, evolution, cessation and structure of the drought 3. Assess and reduce uncertainties in the prediction of drought 4. Compare the similarities and differences of current drought to previous droughts and those in other regions 5. Apply our progress to address critical issues of importance to society

1. QUANTIFY THE DROUGHT Observational Networks Surface Storage Change 200 m GRACE satellite

Elnora Buffalo Lake Buffalo Lake Stettler Kirkpatrick Lake Duck Lake Hague Warman Saskatoon

DrumhellerHand Hills Sounding Creek Sibbald Big Stone Gem Cessford Cluny Buffalo North Duchess

Dam Forty Mile Coulee Elkwater Warner Pakowki Cypress Verlo Instow Shaunavon Swift Current

9 1. QUANTIFY THE DROUGHT Observational Networks Surface Storage Change 200 m GRACE satellite Crestomere Lake Gull Lake Ponoka Sylvan Lake Red Deer Dickson DamInnisfail Olds Pine Lake Elnora Buffalo Lake Buffalo Lake Stettler Kirkpatrick Lake Duck Lake Hague Warman Saskatoon Saskatoon Vanscoy Blucher Bruno Many Springs Irricana Calgary Carseland OkotoksHigh River DrumhellerHand Hills Sounding Creek Sibbald Big Stone Gem Cessford Cluny Buffalo North Duchess Cavendish Tyner Swanson Conquest Enchant Barons Medicine Hat Mud Lake Orton Lethbridge Oldman Dam Forty Mile Coulee Elkwater Warner Pakowki Cypress Verlo Instow Shaunavon Swift Current Smith Coulee Del Bonita Legend Wells in South Saskatchewan Observation Well Location Kilometers

10 2. UNDERSTAND THE DROUGHT Drought Vertical Scale Drought Non-drought Non-drought Storage of Water Horizontal Flux of Water

11 3. SIMULATE AND PREDICT THE Global Climate model DROUGHT NWP Model AGCM3 200 km Global Reanalysis GEM 15 km Regional Climate Model CRCM4 45 km Cloud-Resolving Model GEM-LAM 2.5 km Forcings and Initial conditions Process Parameterizations LDAS data flow LDAS Land Surface Hydrology Models CLASS, MESH 15 km CPM, CRHM 1 km Hydrological Process Models Regional Analysis & obs (for LDAS)

12 Canadian Prairie Runoff Generation Snow Redistribution to Channels Spring melt and runoff Dry non-contributing areas to runoff Water Storage in Wetlands

13 Runoff Non-Contributing Areas to Streamflow a Prairie Characteristic

14 Prairie Streamflow very seasonal Smith Creek, Saskatchewan Streamflow m 3 per second Drainage area ~ 450 km 2 Average High Year 2000 Low Year No baseflow from groundwater 27-Dec 27-Nov 28-Oct 28-Sep 29-Aug 30-Jul 30-Jun 31-May 01-May 01-Apr 02-Mar 31-Jan 01-Jan Hydrological drought can be viewed as the absence of prairie runoff

15 Sparse Prairie Streamflow Network for Drought Analysis Burn et al., 2008 Inadequate coverage to characterise prairie runoff

16 How to Characterise Hydrological Drought for the Prairies? River flows reflect Rocky Mountain, but not Prairie hydrological conditions. Streamflow network is very sparse. Modelling required to create a hydrological drought surface for the Prairies over small first order basins.

17 Cold Regions Hydrological Model (CRHM) Drought Hydrology Simulation Create virtual representative basin models, which can produce simple exceedence probability drought indices Allows comparison of basin response to drought conditions and to historical variability Requires high resolution driving data over entire Prairies for normal ( ), non-drought ( ) and drought periods ( ) Snowfall, rainfall Temperature Humidity Wind speed

18 CRHM Prairie Module Structure Garnier and Ohmura s radiation module Global radiation Max. sunshine Observation module Temperature, Windspeed Relative Humidity Vapour Pressure Precipitation Sunshine hour module Sunshine hour Walmsley s windflow module Long-wave module Interception module Adjusted windspeed Rainfall Snowfall PBSM SWE Gray and Landine s Albedo module Adjusted short- and long-wave radiation Canopy effect adjustment for radiation module albedo EBSM snowmelt All-wave radiation module Short- and long-wave radiation Gray s snowmelt infiltration module, Green-Ampt infiltration Snow INF Rain INF Runoff Granger s evaporation module, Priestley and Taylor evaporation module Evap in recharge and rooting zones Wetland module Runoff Muskingum routing module

19 Impact of Wetland Change on Streamflow in a Wet Year Scenarios of Smith Creek Spring Discharge near Marchwell Daily Mean Discharge (m 3 /s) 30 "Normal Condition" 25 high natural wetland extent 20 minimum wetland extent Mar 10-Mar 19-Mar 28-Mar 06-Apr 15-Apr 24-Apr 03-May 12-May 21-May 30-May Flood: Record High Discharge Volume

20 Impact of Wetland Change on Streamflow in a Drought Year Scenarios of Smith Creek Spring Discharge near Marchwell Daily Mean Discharge (m 3 /s) "Normal Condition" 1.2 high natural wetland extent 1 minimum wetland extent Feb 20-Feb 29-Feb 09-Mar 18-Mar 27-Mar 05-Apr 14-Apr 23-Apr 02-May Drought: Lowest Discharge Volume on Record

21 Drought Hydrology Simulations Station locations & Prairie ecozone

22 Summer Growing Season Climate Normals ( ) Dry southwestern zone is suited for pasture rather than dryland farming

23 CRHM Surface Water Drought Modelling CRHM was used to create virtual model of typical prairie upland basin Model was run over climate normal period ( ) 1990) Output during drought period was compared to normal period and spatially interpolated

24 CRHM model of small upland Small stream basin prairie stream basin CRHM model HRU1 HRU2 HRUs 1 and 2 alternate between cropped and fallow HRU3 is grassed HRU3

25 Prairie Spring Discharge 2001 Drought

26 Prairie Spring Discharge 2005 Wet Year

27 Spatial Variation of Prairie Soil Moisture (Drought vs Wet) Mean for normal period 332 mm Drought period: distribution wide, variance large, median > mean Wetter period: distribution loses low soil moisture, variance smaller, median < mean Drought Wet Probability density of soil moisture

28 Spatial Variation of Evapotranspiration (Drought vs Wet) Mean for normal period 352 mm Drought period: distribution wide, variance large, median >> mean Wetter period: distribution symmetric, variance greatly reduced Drought Wet Probability density of evapotranspiration

29 Climate Change Impacts Virtual basin model also useful for estimating climate change impacts on Prairie hydrology Climate warming has a strong effect on cold season hydrological processes.

30 Prairie Streamflow & Climate Change First more, then less Three most reliable climate change scenarios suggest increases in annual prairie winter temperature and precipitation from the average: ºC and +11% ºC and +15.5% Using these scenarios in the virtual upland basin results in a 24% rise in 2050 spring runoff, but a 37% drop by 2080, compared to conditions in the mid 1970s.

31 Prairie Climate Change Winter Snow Winter Snow Accumulation at Bad Lake, SK Normal SWE (Winter of 1974/75) SWE (Winter of 2049/50) SWE (Winter of 2079/80) SWE (mm) 01/10/ /10/ /10/ /11/ /11/ /12/ /12/ /01/ /01/ /02/ /02/ /03/ /03/ /04/ /04/ /04/1975

32 Prairie Climate Change Spring Runoff Spring Runoff from Creighton Tributary at Bad Lake, SK Runoff (mm) 01/10/ /10/ /10/ /11/ /11/ /12/ /12/ /01/ /01/ /02/ /02/ /03/ /03/ /04/ /04/ /04/1975 Normal Spring Runoff (Spring of 1975) Spring Runoff (Spring of 2050) Spring Runoff (Spring of 2080)

33 Conclusions Prairie streamflow is inherently unreliable in drought, Hydrological droughts migrate across the Prairies. Drought increases the variability of soil moisture, evapotranspiration and snowpack Future climate change likely to first increase then decrease spring snowmelt runoff from prairie drainages. Flooding Shortages If droughts also increase, this means greater use will need to be made of mountain-derived river water supplies for agriculture

34 Thanks! The gracious invitation of ISACS-3 and financial support of National Natural Science Foundation of China made this presentation possible.

The Link between Soil Moisture and Drought as Examined in DRI

The Link between Soil Moisture and Drought as Examined in DRI John Pomeroy Centre for Hydrology Department of Geography University of Saskatchewan, Saskatoon THE TEAM Co-leads leads: Ron Stewart (PI, McGill)