van der Kamp: Characterizing drought:

Transcription

1 van der Kamp: Characterizing drought: - Comparison of evapotranspiration from forest and grassland Fluxnet sites (with Barr and Zhan, Environment Canada). - groundwater levels water level records for shallow provincial observation wells (with Sauchyn, U of Regina). - Comparison of geological weighing lysimeters and GRACE (with Yirdaw and Snelgrove, Memorial U). - Soil moisture regional: geological weighing lysimeters (with Anochikwa and Barbour, U of Saskatchewan).

2 Saskatchewan BERMS Forest flux sites (Old Aspen OA, Old Black Spruce - OBS and Old Jack Pine OJP) compared with Alberta Grassland site (ABG): Comparison of Monthly E,α and G s Between Dry year (2003 for SK Sites, 2001 for ABG) And Wet Year 2005 [Zhan et al. in prep]

3 Duck Lake SK Observation wells: water levels, [Source: SK Watershed Authority, Duck Lake #1 Duck Lake # Aquifer Aquitard 34 m 118 m Aquifer 134 m 480 Aquitard Water table depth (m) Duck Lake 1 Depth below ground level (m) Water level (m asl) Duck Lake #2 Observation well

4 Shallow observation wells in SK water level records : water table depths below ground level (m) Water level (m bgl) ATTON's Lk CONQ 501 DUCKLAKE 1 FORGET MELFORT SIMPSON 13 STENEN SWANSON VERLO Years

5 Shallow observation wells in SK water level changes Water-table drawdown during the drought averaged about 0.5 m, corresponding to ~ 150 mm groundwater storage depletion Watere level change (m) ATTON's Lk CONQ 501 DUCKLAKE 1 FORGET MELFORT SIMPSON 13 STENEN SWANSON VERLO Average Years

6 Overview of the Weighing Lysimeter Instrumentation Fundamentals Change of mechanical surface loading is instantaneously transmitted to deep saturated formations resulting in change of pore water pressure; Piezometers in saturated formations can therefore detect pore pressure changes due to hydrological processes such as: Snow accumulation; Conceptual Sketch of Piezometric Weighing Lysimeter Installation Rainfall; Evapotranspiration tens of meters p Aquitard - highcompressibility - lowpermeability Pressure Transducer Van der Kamp et al, 2003 t

7 Deep observation wells = Geological weighing lysimeters southern Saskatchewan, Duck Lake #2 Hearts Hill Lilac Tyner Obs well average change (m) Water level change (m) Year

8 Regional water storage changes in southern Saskatchewan: - Average of 4 Geological Weighing Lysimeter wells, - Average of 9 water table wells Average - Geological weighing lysimeter wells (m) Average - shallow water table wells (m) Water storage change (m) Years

9 Regional water storage changes in southern Saskatchewan: - GRACE for southern Saskatchewan [provided by Yirdaw and Snelgrove] - Average of Geological Weighing Lysimeter wells - Average of water table wells Average - Geological weighing lysimeter wells (m) GRACE (m) Average - shallow water table wells (m) Water storage change (m) Years

10 Location of Duck Lake observations wells and Watflood grid cell [Marin et al. in prep.] CANADA DUCK LAKE REGION Approximate Eolian Hummocky Sand boundary SASKATCHEWAN Grid Of study Approximate Hatfield Valley Aquifer boundary North Saskatchewan River Precipitation gauges Duck Lake Observation Wells No s 1 and 2 South Saskatchewan River

11 Comparison of Duck Lake No. 2 (geological weighing lysimeter) water level record with Watflood simulation of the vertical water balance Water Storage Change (mm) Vertical Water Balance - Modeled with WATFLOOD Water level Duck Lake No. 2 - Observed Year

12 Comparison of Duck Lake No. 1 (water table storage change) with Watflood simulation of the changes of groundwater storage Water storage change [mm] Watflood Lower zone storage (LZS) Water Table Storage Change - Duck Lake No. 1 Observed Years

13 Modeling of Piezometric Lysimeter Response to Rainfall & Evapotranspiration and water table changes (Anochikwa, MSc U of Saskatchewan) Evapotranspiration Rainfall Rainfall (Using Environment Canada Data)

14 Simulation of observed lysimeter response using SeepW/SigmaW geotechnical model RESULTS: Superposition (or Coupled) and Measured (C) Properties Value Bbar E (MPa) 560 n 0.26 Ss (/m) 1.29E-5 Kv (m/day) 1.2 E-5 D (m2/day) 1.94 Characteristi 229 c time scale (days)

15 Water storage changes observed for Duck Lake SK observation wells : Duck Lake No. 1 Shallow water table well with specific yield = 0.30 Duck Lake No. 2 Deep well in confined aquifer (geological weighing lysimeter) Duck Lake No Duck Lake No Y ear

16 Shallow observation wells in AB water level records : water table depths below ground level (m) 0.00 Water Level (m bgl) Well 105 Well 106 Well 129 Well 159 Well 162 Well 172 Well 219 Well 251 Well 252 Well 260 Well 371 Well Years

17 Shallow observation wells in AB water level changes Water table drawdown averaged ~ 0.6 m corresponding to about 200 mm depletion of groundwater storage. But note lack of recovery after the drought Water level change (m) Well 105 Well 106 Well 129 Well 159 Well 162 Well 172 Well 219 Well 251 Well 252 Well 260 Well 371 Well 379 Average Years