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C:\Program Files\CRHM\Examples\badlakeflow7475jp.prj

Hydrology of Prairie Droughts

John Pomeroy, Kevin Shook, Robert Armstrong, Xing FangCentre for Hydrology

University of SaskatchewanSaskatoon, Sask

www.usask.ca/hydrology

Non-Contributing Areas to Streamflow a Prairie Characteristic

Prairie Runoff GenerationSnow Redistribution to Channels

Spring melt and runoff

Water Storage in Wetlands

Dry non-contributing areas to runoff

Prairie Hydrology – don’t blink

0

5

10

15

20

25

01-Jan

31-Jan

02-Mar

01-Apr

01-May

31-May

30-Jun

30-Jul

29-Aug

28-Sep

28-Oct

27-Nov

27-Dec

Str

eam

flow

m3

per

seco

nd

Average 1975-2006

1995 High Year

2000 Low Year

Smith Creek, Saskatchewan

Drainage area ~ 450 km2

No baseflow from groundwater

Hydrological drought can be viewed as the absence of prairie runoff……

How to Characterise Hydrological Drought for the Prairies?

River flows well gauged, but subject to abstraction, storage and do not reflect Prairie hydrological conditions.

Streamflow network is more representative but is sparse, and subject to changes in land cover, drainage, abstraction, storage.

Possibility to model prairie runoff generation and related hydrological processes to create a hydrological drought “surface” for the Prairies using atmospheric driving data and standardised representation of prairie snow redistribution, melt, runoff generation, infiltration and evaporation.

Modelling Objectives

To Demonstrate the: differences between drought and non-drought

hydrological cycling at the surface, evolution of hydrological drought over time and

space Calculated Variables as ratios to non-drought

conditions (~Hydrological Drought Indices~) Snow Accumulation peak SWE, duration Spring Freshet total, duration Actual ET/PET growing season Soil Moisture spring, summer, fall

Cold Regions Hydrological Model (CRHM) Drought Hydrology Simulation Model the effects of local drought meteorology on the

hydrology of ”representative”, first-order prairie basins Create “virtual” basin models, which can be applied to

gridded datasets Allows comparison of basin response to drought

conditions and to normal variability Requires high resolution driving data over entire Prairies

for normal (1961-1990), non-drought (1962-1987) and drought periods (1999-2004) Snowfall, rainfall Incoming shortwave radiation, cloudiness or sunshine hours Temperature Humidity Wind speed

CRHM – Prairie Hydrological Model Configuration

Flow Chart in Cold Regions Hydrological Modelling

Platform (CRHM)

CRHM Tests Creighton

Tributary of Bad Lake-well drained semi-arid

St. Denis National Wildlife Area-internally drained sub-humid

Case Study at St. Denis, Sask (2007) Granger-Gray Evaporation module

Validation site

Eddy CovE = 2.2 mm

Granger-Gray E ≈ 2.6 mm

Aug 5, 2007Aug 5, 2007

Udir

mmmm

CRHM Hydrological Response Unit (HRU) Configurations

Fallow Stubble

Grass Coulee

Stream

Creighton Tributary, Bad Lake

Cultivated

Wooded Wetland

Pond

Wetland 109, St Denis

Well Drained Poorly Drained

CRHM Hydrological Indices Snowcover duration Peak SWE Spring discharge (freshet) amount Streamflow duration AET/PET Soil moisture

NARR Variables

All data required by CRHM are available from NARR

Quality of data varies Incoming shortwave radiation is computed

from modelled clouds, NOT from surface measurements

Edmonton 1979-2000

Winnipeg 1979-2000

Why not use all NARR data?Winnipeg daily Tmin & Tmax, 1979-2000

NARR precipitation

Unusable

Calgary 1999-2003

CRHM Simulations

Winnipeg and Calgary to date HRUs grass, cropped Evaluation of changes to drought

hydrology

Calgary SWE on GRASS 1961-89

Winnipeg 2002 Drought SWE

Winnipeg Maximum SWE

Winnipeg Spring Freshet

CRHM Gridded First Order Hydrology

Runs to be completed for all Prairies this winter, then mapped

Will provide first physically based, comprehensive estimation of runoff generation from first order basins in Prairies

Useful information for DEWS (soil moisture, SWE, peak flow, duration of flow, wetland level, actual evaporation)

Actual evapotranspiration maps using remote sensing, splined observations, reanalysis

Provides a hydrological modelling tool for general prairie application

Advises application of VIC and MESH to Prairie environment