Modelling soil moisture with the VIC model during drought (Lei Wen)

Modeling Soil Moisture with theVIC Model During DroughtLei Wen 1 , Charles A. Lin 1,2 , John Pomeroy 31 23

1. VIC prairie soil moisture modeling• three soil layers (0-20 cm, 20-100 cm, 0-100 cm), 0.25 ° x0.25 °, dailytime step• starting on 1 January, 1950, real-time forecasting with a lead time up to 35-day• meteorological forcing: 1,167 stations + operational Canadian GEM forecast +operational 40-number super ensemble forecast + operational CMC ensembleseasonal forecast• VIC soil moisture + its 60-yr climatology (1950-2009) calculating a soilmoisture index SMAPI (Soil Moisture Anomaly Percentage Index)• VIC SMAPI compares favorably with three independent drought datasets, canexplain historical drought events in the Prairies• VIC soil moisture is updated daily at present; SMAPI results are publiclyaccessible online (http://www.meteo.mcgill.ca/~leiwen/vic/prairies/)

1,167 met stations (black dot) on thePrairies4393 grid points, 0.25 ° x 0.25 °Flat terrain and non-contributingdrainage areas, which bringschallenges to hydrological modeling

5 additional validationcatchments in red7 calibrationcatchments in green;VIC calibration and validation6 moisturesites‣ We calibrate the six VIC user-calibrated hydrologicalparameters using observed daily hydrographs at the outlets ofeach of the 7 calibration catchments.‣ The validation of the calibrated VIC over the Prairies involvesthe following three parts.1. First, we validate VIC using observed daily hydrographs fromthe same 7 calibration catchments taken over different periodsthan for calibration.2. Second, we further validate VIC using observed dailyhydrographs from 5 additional catchments.3. Third, we compare simulated soil moisture anomalies with in situobservations from 6 Alberta sites.We define 7 VICsimulation regions over thePrairies, which is based onthe annual precipitation of1950-2009

2. VIC soil moisture60-yr (1950-2009) average of soil moisture (top 1-m) over the Prairieswith the 200 mm soil moisture contour, showing modeled very dry areas200 mm is the VICaverage wilting pointIdentifications of the Palliser Triangle region and the Prairie Dry Belt (Jones, 1978) in South Prairies.

DRI periodSoil moisture deficit of twoperiods with respect to the60-year climatology:• 1999-2005 (top)• 2001-2002 (bottom)

3. Soil Moisture Anomaly Percentage Index (SMAPI)FrequencySMAPI100%• The soil moisture climatology reflects local characteristics and mirrors the hydrometeorologicalphenomena of a region• Applying the concept of relative soil wetness for measuring drought severity• Keyantash and Dracup, BAMS, 2002 (second highest ranking among the five evaluatedindices for agricultural drought)Drought classifications based on SMAPI0.300.250.200.150.100.05HarbinXifengzhenHaihongJinzhouZhumadianXuzhouSuxianZhenjiangJinjiangBaiseAverage0.00-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60SMAPI(%)

Reconstructing prairie drought historySouthern Saskatchewan, April 2002;Taken from StewartExampleDaily SMAPIdistributions of thethree soil layers forApril 20, 2002,together with theApril-2002 average

Annual SMAPI for the period of 1997-2005

4. Comparing SMAPI with three datasetsa. North American Drought Monitor (NADM)NADMSMAPI

NADM from Richard Rieger, Agriculture and Agri-Food Canada

VIC SMAPI, June 30, 2009VIC SMAPI, June-2009 average

. National Drought Indice (PDI) of Agriculture and Agri-Food CanadaLocations of PDI stationsDry regionWet region

c. Environment Canada PDSIhttp://www.meteo.mcgill.ca/~leiwen/vic/prairies/month-seasonalannual/index_compare.htmlFor the period 1950-2005 (monthly)

Monitoring andforecasting Winnipeg2009 flooding

Real-time droughtforecasting with alead time up to 35-d

35dReal-time China drought forecastForecast verifying on April 4, 2010 withdifferent lead time25d15d4dMonitoring(Drought Monitor,China MeteorologyAdministration

Thanks very much !Merci beaucoup !