Prairie Drought Hydrology Prediction using the Cold Regions Hydrological Model

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1 Q Q Q Q S Q si t r e a u p p p t Q so Q n Q ln S u n A c t fo rm d a ta d d d d u C : \ P r o g r a m F ile s \ C R H M \ E ro D fo D ro fo n M a x g lo b a l C a lc H r c a lc s u n Q si t r e a u p r a in sn o w S u n A c t tm a x t m in tm e a n e a m e a n u m e a n r m e a n n e w sn o w o b s n e t r a in n e t s n o w in t c p e v a p in t c p n e t c u m n e t n e t a ll R n Q g Q s n e t rn Prairie Drougt Hydrology Prediction using te Cold Regions Hydrological Model Pomeroy, J.W., Fang, X., Armstrong, R. and K. Sook, Centre for Hydrology, University of Saskatcewan e v a p tra n s p o n e v a p p b s

2 Background Prairie Drougt Hydrology Prairie drainage is primarily via small streams and slougs wic eiter form internally drained (closed) basins tat are locally important but non contributing to river systems tat drain te prairies, OR drain directly to small prairie rivers (Battle, Souris, Assiniboine) or large mountain rivers tat cross te prairies (Saskatcewan) >80% of noff during snowmelt period Redistribution of snow in winter period critical to formation of noff contributing area In severe drougt streamflow ceases completely in summer

3 Non contributing Areas to Streamflow

4 Rationale Prairie ydrological modelling requires consideration of te following: 1. Transport of water in liquid, vapour and frozen states (noff, percolation, evaporation, sublimation, blowing snow); 2. Coupled mass and energy balances; 3. Pase cange in snow & soils (snowmelt, infiltration in frozen soils, soil freezing and tawing); 4. Snow and rain interception in forest canopies; 5. Episodic flow between soil moisture, groundwater, ponds and streams. 6. Variable storage, drainage and contributing area 7. Land use cange Tese are not normal features of ydrological or land surface models

5 Cold Regions Hydrological Model CRHM Modular purpose built from modules Modules based upon +40 years of prairie ydrology researc at Univ of Saskatcewan Hydrological Response Unit (HRU) basis landscape units wit orizontal interaction, ponds, no need for stream HRUs assumed internally uniform, basis for coupled energy and mass balance HRUs connected aerodynamically for blowing snow and via dynamic drainage networks for streamflow

6 CRHM Module Development DATA ASSIMILATION Data interpolation to te HRUs PROCESSES SPATIAL PARAMETERS Basin and HRU parameters are set. (area, latitude, elevation, ground slope, aspect) Infiltration into soils (frozen and unfrozen) Snowmelt (prairie & forest) Radiation level, slopes Evapotranspiration Snow transport Interception (snow & rain) Sublimation (dynamic & static) Soil moisture balance Pond water balance Sub surface noff Routing (illslope & cannel) Advection

7 Blowing Snow water transport

8 Blowing Snow [ ] E B x dx ds x =P p F x E M, dt x P w in d d i r e c ti o n zb E F B F susp susp s u s p e n s io n la y e r F s a lt s a lt a t io n la y e r snow pack * d S /d t F M F e tc = x References: Pomeroy, Gray & Male, 1993; Pomeroy & Li, 2000 s a lt

9 Snow Redistribution to Wetlands St Denis

10 Snowmelt du Q m Q n Q H Q E QG Q D=, dt M = Q, m ρw B f Daily Energy Balance α References: Gray & Landine, 1988

11 Infiltration into Frozen Soils Snowmelt Water Restricted Infiltration Limited Infiltration or Parametric Equation INF = 1 θp SWE Unlimited Infiltration Soils References: Granger et al., Gray et al., Zao & Gray Runoff

12 Infiltration into Unfrozen Soils Green Ampt Infiltration Depends on Ponding Time Iterative Solution References: Green & Ampt, Ogden and Sagafian, Pietroniro in Pomeroy et al., 1997

13 Evaporation Includes transpiration Granger Gray extension of Penman offers a pysically based, practical solution (Granger and Gray, 1989) No need to rely on surface resistance and soil moisture assumptions and cumulative errors Responsive to atmosperic umidity feedbacks

14 Evaporation Granger Gray Q E= QN G [ s Q Q G C vdd a / r a ] s G γ Ta, ea, uz QE QH QA=QN QG es = f (ea, Ta Ts) Ts, es, z0 Surface Vegetation & Soil QG Water drawn from 1) canopy 2) depressional storage 3) recarge zone 4) deep soil References: Granger & Gray (1989), Granger & Pomeroy (1997)

15 Granger Metod Accuracy Similar to Metods wit Greater Parameter Needs RMS ERROR 0.58 mm D a i l y M o d e l l e d v s M e a s u r e d E v a p o r a t i o n Granger Gray Penman Monteit 0.65 mm St Denis Bulk Transfer LSS 0.96 mm 5 M o d e lle d ( m m ) G D 1 P M B u lk T r a n s f e r M e a s u re d (m m ) 4 5

16 Soil Moisture Balance (SMBAL) Snowmelt Interception Snowmelt Green Ampt Infiltration Infiltration Mass balance and flow from two soil layers & groundwater Runoff Recarge Zone Soil Column INF GW SSR E SURFACE Trans Δθ=0 Groundwater References: Leavesley et al. Dornes et al Evapotranspiration Subsurface Discarge Groundwater Discarge

17 CRHM Prairie Hydrological Model Configuration Flow Cart in Cold Regions Hydrological Modelling Platform (CRHM)

18 CRHM Tests Creigton Tributary of Bad Lake well drained semi arid upland St. Denis National Wildlife Area internally drained sub umid upland

19 CRHM HRU Configurations Fallow Stubble Grass Coulee Cultivated Wooded Wetland Stream Pond Creigton Tributary, Bad Lake Wetland 109, St Denis

20 Snow Accumulation and Ablation at Bad Lake

21 Snowmelt Runoff at Bad Lake

22 Snow Accumulation at Wetland 109, St Denis

23 CRHM drougt simulation St Denis

24 Snow Hydrology in Drougt Bad Lake Sensitivity Test Drougt Factors Winter Precipitation Winter Air Temperature Fall Soil Moisture Summer Vegetation Growt Drougt Response Winter Evaporation Maximum Snowpack Spring Infiltration Spring Stream Discarge Fang and Pomeroy, 2007

25 Results so far First successful ydrological model ns for small prairie basins no calibration Winter snow redistribution and fall soil moisture control spring noff response Extreme sensitivity of spring noff to winter precipitation and temperature due to ydrological interactions witin prairie basins Multi season water balance memory in pond level controls wetland pond response

26 Next Steps CRHM suitable to be driven by CRCM (rescaling time and space inputs possible) or reanalysis data Develop classic virtual small prairie basin configurations (well drained, poorly drained) and n water balance and streamflow calculations in tese for grid cells across te prairies during te recent drougt. Snowpack, soil moisture streamflow, contributing area and pond level response to drougt development and cessation can be quantified and mapped across Prairies. Working wit HAL to include snow redistribution features in MESH for two way coupling wit atmosperic models.