a high-resolution land model with groundwater lateral flow ... · institute of atmospheric physics,...
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Zhenghui Xie, Yujing Zeng , Shuang Liu, Junqiang Gao，
Binghao Jia, Peihua Qin, Jinbo Xie
The 24th Annual CESM Workshop, June 17-19, 2019, Boulder
A high-resolution land model with groundwater lateral flow, water use and soil freeze-thaw front dynamics and
its applications in an endorheic basin
State Key Laboratory of Numerical Modelling for Atmospheric Sciences
and Geophysical Fluid Dynamics (LASG)
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing
Outline
Motivation
Developing a land model coupled with groundwater
lateral flow, human water regulation and the
changes in soil freeze–thaw fronts
High-resolution simulations in Heihe River Basin
Summary
3
On evaluation, in 2000, more than 300 billion tons of available water was
depleted by groundwater over-exploitation.
Many recent studies have shown that in some key regions, the GW
resources were rapidly depleted.
(Zou & Xie et al. 2013)
(Rodell et al. 2009)
India China
(Döll et al. 2012)USA
Available water resources depletion
4
GW table declining caused by over-exploitation may reduce the soil moisture and
environmental base flow, and then induce drought and damage ecosystems.
Large-scale irrigation may modify the water and energy fluxes between the land and
atmosphere, and further influence the atmospheric circulation.
So, it’s very meaningful for us to study the effects of anthropogenic water
exploitation on water availability, ecohydrologic and climate systems.
Human water exploitation modifies the environment
and climate system
5
Groundwater lateral flow (GLF) cannot be ignored
GLF shapes the pattern of groundwater resource around the world.
GLF recharges the groundwater depression cones caused by over-exploitation,
and relieves the side effects of human GW pumping.
Lateral flowLateral flow
GW depression cone
6
Distribution of permafrost and seasonally frozen
ground in China (Xin Li,et al.,2008)
Distribution of permafrost and seasonally frozen
ground in Northern Hemisphere
Frozen soil：all kinds of ice-containing frozen soil at 0℃ or below 0℃。
Permafrost and seasonally frozen soil account for 24% and 30% of the land
area in the north Hemisphere, respectively；
In China, The area of frozen soil is equivalent to 72% of land surface.
Current land model didn’t describe freeze–thaw
fronts dynamics
7
Current LSMs and ESMs did not consider groundwater lateral flow,
human water regulation and the changes in soil freeze–thaw fronts.
Motivitation
Developing a high-resolution land model coupled with groundwater
lateral flow, human water regulation and the changes in soil freeze–
thaw fronts
Applying the developed models to study effects of GLF and human
water exploitation on land surface processes and explore the changes
in frozen soil.
Outline
Motivation
Developing a land model coupled with groundwater
lateral flow, human water regulation and the
changes in soil freeze–thaw fronts
High-resolution simulations in Heihe River Basin
Summary
In this study, we incorporated a quasi-3d GLF, human water exploitation and soil freeze–thaw fronts
dynamics scheme into the CLM4.5, and applied the coupled model to study the effects of both GLF and
human water exploitation on the land surface processes and soil freeze–thaw fronts dynamics.
Xie et al., 2012, JHM
Xie et al., 2018, JGR-Atmosphere
Zeng, Xie, Liu, et al, 2017, ESD
Soil Frost and Thaw Fronts Dynamics
Groundwater
lateral flow
module
Human water
exploitation
module
Water
consumption
in agriculture,
industry, and
live
Influencing water
table
human water regulation
Surfac
e
Water table
Datum plane
X
Y
Z
q
Quasi-3d groundwater
lateral flow scheme
The land model with groundwater lateral flow, human
water regulation and soil freeze–thaw fronts dynamics
Zeng, Xie, Zou, et al, 2017, Journal of Climate
Zeng, Xie, Liu, et al, 2016, JAMES
Gao,,Xie, Wang,, et al, 2019, JAMES
10
0
( , ) , 0
, ,0 , , , 0
, , 0
e
h h hn Kf Kf R L x y t
t x x y y
h x y h x y x y t
K f h t h Q x y t
n
Eight Flow Direction
0.5 tan / 8w S
Two-dimension shallow water equations
Discretization
8
1
1 18 81 1
1 1
1,2, ,
n
e
n n
k kk k ke n n n n e
n nn n
wT h hhn R L
t l S
n w T w T nh i h n R i h i i N
t l S i l S i t
Parameterization
0 0
0 min
1 2 1 2 0 0 00 0
00 0 0
exp ,1
, , exp
exp exp
m m
s
zwt d zwt d
z aK K f f f
f bs
zT T T T K z T Kdz K dz K f zwt d
f
h h dzT Kdz K dz K f zwt d
f f
，
Model developed 1: Groundwater lateral flow scheme
(Xie et al., JHM,2012)
11
Model developed 2: Human water regulation scheme
CLM4.5Exploitation
＆consumption Schemes
Changes of land surface processes
Groundwater
exploitation Qg
Irrigation
Q1
Back to soil
Q1+Q2
Waste Water
α3Q3+α4Q4+α5Q5+α6Q6
RiverWell
Soil
Aquifer
Human water withdrawal＆consumption Schemes
Surface water
Intake Qs
Ecosystem
Q2
Industry
Q4
Live
Q5
Public
Q6
Livestock
Q3
Net water loss
(1-α3)Q3+(1-α4)Q4+(1-α5)Q5+(1-α6)Q6
(Zeng &Xie et al., JAMES,2016)
12
Estimation of human water withdrawal and consumption amount
(Zeng &Xie et al., ESD,2017)
Model developed 3: A two-directional freeze and thaw algorithm
(Gao & Xie et al, JAMES, 2019)
2
2
2
22
( ) ( )
f
f
f f
f
f
Dz
L
Dz
L
Dz z
L
zD L z
11 1 1
22 2 2 1
1
1
( )( )2
( )( )2
( )( )2
ii
i i i n
n
RN L z
RN L z R
RN L z R
1 10
0
1 1
1/22
1 1 12
0
1 1 1
1 0
( )( )2
2 ( ) / ( )
i if
n i f n
n n i
i i i
f i n i n i n i
n n n
f i f
zD N L z R
z R R D N L
z z z
The Stefan equation assume
all the heat is used for the
freezing or melting of
ground ice.
Soil profile is modelled as a
homogeneous medium
Use the Stefan equation
in a multi-layered system
The FTFs scheme coupled with CLM4.5
14
Update FTF depths s1n+1,s2n+1
Solve heat equation to get temperature T1in+1
Solve soil water equation to get soil unfrozen water content W1in+1
Return initial soil hierarchy and update Tin+1
Given initial FTF depths
According to the FTF in the original stratification,update soil hierarchy
Phase change?
Update soil unfrozen water content Wliqn+1
Soil temperature Tin+1、soil ice Wice
n+1
Y N
n=0
Tin+1=T1i
n+1,Win+1=W1i
n+1
n=n+1
N<TY
End(Gao & Xie et al., 2017)
The main calculation process in CAS-LSM and its coupling
with GLF, HWR, and FTFs
15(Xie et al., 2018,JGR)
Model soil layers Soil water and iceComputing method
for FTFs
Find 0º table
in each layer Obtain FTFs
Update soil
temperature
Soil temperature module with FTFs
Forcing datasets
Canopy interception
Surface runoff
Surface energy fluxes
Lake hydrology
Carbon and Nitrogen
Soil temperature
Soil water
Groundwater
River runoff
Calculation process in CAS-LSM
t=t+∆t
Reduce
groundwater storage
Update groundwater
levels
Groundwater levels
Calculate groundwater
lateral flux
Update groundwater
levels and storage
River routing
Evaporation and infiltration
Soil hydrology module with HWR and GLF
Read surface water use data Read groundwater use dataNet water input
Reduce river
water storage
Compute Surface runoff
Update aquifer information
Add water on top soil layer
Calculate soil water and ice
Calculate subsurface drainage
Soil temperature
Outline
Motivation
Developing a land model coupled with groundwater
lateral flow, human water regulation and the
changes in soil freeze–thaw fronts
High-resolution simulations in Heihe River Basin
Summary
Experimental design
Study domain: Heihe River Basin
Resolution：1-km
Simulation period： 1981-2013
Atmospheric forcing : ITP (Dataset
from Institute of Tibetan Research,
Chinese Academy of Sciences)
Three runs:
EXP1 (Only GLF was included)
EXP2 (GLF + HWR)
EXP2 (GLF + HWR + FTFs)
17
Validation 1：groundwater observations from wells
18
If the GLF is not accounted,
the modeled water table in
the middle stream is
obviously deeper than it is
in the observations.
After the GLF was
incorporated, in the EXP1
and EXP2 simulations. the
modeled results were much
closer to the observations
than they are in the control
simulation.
SH
LH
Gro
un
d T
We compared our modeled results of sensible heat flux, latent heat flux and ground
temperature with observations from several flux stations.
Arou station Gobi station Luodi station
Validation 2：observation from flux towers
19
20
In the EXP1 simulation, we can see that the evapotranspiration in middle
reaches of the basin is very weak.
In the EXP2 simulation, we can identify some areas with strong
evapotranspiration in the middle reaches caused by the irrigation.
This high-value regions can also be identified in the remote sensing data.
Validation 3：remote sensing data of ET
Validation 4：FTFs
Soil freeze–thaw fronts
We compared observed and simulated daily soil frost and thaw front depths at
Hulugou site in the Heihe River Basin from 2011 to 2012.
21
Validation 4：FTFs
We compared the spatial distribution of the permafrost in the Heihe River Basin.
22
23
Spatial distribution of the climatologic states for the depths
of FTFs and ground temperature
24
Interannual variations in frozen soil
permafrost areas
natural seasonally
frozen areas
human-dominated areas
25
Interannual variations in land-atmosphere exchange over the
permafrost zone.
precipitation evapotranspiration
latent heat flux sensible heat flux
carbon use efficiency net ecosystem exchange
26
Interannual variations in land-atmosphere exchange over the
human-dominated zone
26
precipitation evapotranspiration
latent heat flux sensible heat flux
carbon use efficiency net ecosystem exchange
Outline
Motivation
Developing a land model coupled with groundwater
lateral flow, human water regulation and the
changes in soil freeze–thaw fronts
High-resolution simulations in Heihe River Basin
Summary
28
Brief summary
We developed a land model coupled with a high-resolution scheme of
groundwater lateral flow, human water regulation and the changes in
soil freeze–thaw fronts. The developed model performed well in site
validation in Heihe River Basin.
Based on the developed model, we preliminarily explored the impacts of
groundwater lateral flow and some human activities on land processes
from the perspectives of regional scales.
Also we give the distribution of permafrost and seasonally frozen
ground and revealed the changes in soil freeze–thaw fronts.
Groundwater lateral flow can essentially change the groundwater table
pattern and influence other related land processes, even the spatial
distribution precipitation and wind field.
