Micro-scale to Meso-scale: An
update on the IP3 sub-grid
sub grid soilsoil
water budget
by
E.D. Soulis, J. Craig, L.Liu, V.Fortin
mostly
University of Waterloo
Department of Civil and
Environmental Engineering
Acknowledgments
• Funding and patience
-
IP3 – John Pomeroy et al
MAGS – H. Woo et al
MSC/CRB - B.
B G
Goodison,
di
D
D. V
Verseghy,
h R
R. St
Stewartt
NWRI - A. Pietroniro, P. Marsh
NSERC Partnership Program
• Scientific help and guidance
- D. Verseghy, A. Pietroniro, M. McKay, J. Craig
• Code, parameterizations and
tests
- K. Snelgrove, T. Whidden, S. Fassnacht, G. Liu
Outline
• Introduction
• Limitations of MESH (MAGS) soil-water
budget
• Revised parameterization
• Verification
• Opportunities
pp
Introduction: Modelling Imperatives
• 1) Use generic algorithms
-CRHM
CRHM ttypically
i ll allows
ll
ffor explicit
li it ttreatment
t
t off
HRUs
-MESH/GEM groups representative HRUs
• 2) Do everything we can to minimize number of HRUs
• 3) Use distribution based algorithms
- sum fluxes by area
- or use p
pdfs of important
p
p
properties
p
• 4) Embed as much physics as possible in the tile
algorithms
Peat Plateaus
Courtesy of Bill Quinton
Rural Ontario
3)) Use PDFs for Hydrologic
y
g Properties
p
probaability den sity
Hydraulic radius
L = 2 * area / perimeter
1 km
Lake
Peat plateau
Isolated bog
Fen
0.5
04
0.4
0.3
02
0.2
0.1
0
0
100
200
L (m)
300
Connected bog
Courtesy of Bill Quinton
MAGS Tile
Surface Runoff:
Manning’s Equation
Qover
⎛ 1 ⎞ 5/3
1/ 2
= ⎜ ⎟ ⋅ d e ⋅ Λ I ⋅ Lv
⎝n⎠
Infiltration redistribution interflow:
Ri h d’ E
Richard’s
Equation
ti
−
∂K v (θ ) ∂ ⎡
∂ψ (θ ) ⎤ ∂θ
+ ⎢ K v (θ )
=
∂z
∂z ⎣
∂z ⎥⎦ ∂t
Drainage or Recharge:
Darcy’s Law
qdrain = K v (θ 3 )
0
θ1
l
L
θ2
h
H θ3
Drainage
Ksat0
MAGS Tile
Easy to Interpret
Evaporation
Infiltration
Saturated area
Interflow
Recharge
Retained water
IP3 Tile?
Initial state
T
Transition
i i state
Steady state
S
h
Upper-saturation
Middle-streamline
Lower-total head
New Parameterization
Field Capacity Comparison
Fl ceases when
Flow
h suction
ti gradient
di t equals
l slope.
l
Thus,
Th
and
1/ b
1 ⎛ −ψ a b ⎞
S fc =
⎜
⎟
(b − 1) ⎝ LΛ ⎠
[(3b + 2)
( b −1) / b
− (2b + 2) ( b −1) / b
]
Note the second equation includes both topographic and
soil parameters.
Field Capacity Comparison
θ
θfc2
(Soil
profiles)
p
0.5
04
0.4
0.3
0.2
0.1
0
0
Comparison
p
of Field Capacity
p y
(θfc) estimates
Analytic…
0.1
0.2
0.3soil 0.4
θfc1 based
on
suction0.5
Numerical Analysis Comparison
Silty Loam 1,2 and 3 months
Numerical Analysis Comparison
Improved Recession Curves
Red line is a typical gravity
dominated curve. Green line is
the corresponding suction
dominated solution. WATDrainV2
uses an empirical blend of these
these.
WATDrainV3 will use Equation (1)
which is the blue line in Figure 3.
Scotty Creek, DA = 177 km²
One grid with 2 tiles (peat plateau and fen),
20% of flow from peat plateau diverted to fen
14
Flow (cms)…
…
12
10
8
Modelled
Measured
6
4
2
0
Julian day (2004-2005)
IP3 Tile
Initial state
T
Transition
i i state
Steady state
S
h
Upper-saturation
Middle-streamline
Lower-total head