Experiments and Modeling of Water and Energy Transfer in Agro-ecosystem

Yi LUO Zhu OUYANGYi LUO Zhu OUYANGYucheng Comprehensive Experiment Station, CASYucheng Comprehensive Experiment Station, CAS

Sept, 2002

Outline

(1) Background(2) IEM in Field Scale Framework and Components of the Model

Field Exp., Model Validation (3) IEM in Regional Scale (4) No Conclusion

Background

Processes in Field Scale

Processes in Regional or Watershed Scale

Groundwater

Soil

Land Use/Cover

Ground monitoring

RS

Integrated Ecological Modeling

CropS: Crop and Soil system

model

SWAT/MODFLOW

IEM in Field Scale-Framework and Components

SQED sIP

dt

d12,1

11

SQQD iiiii

ii dt

d

1,,1

SQQD NNNNN

N dt

d

,1

Currently, CropS can simulate:(1) Soil water dynamics, infiltration(2) Evaporation and transpiration(3) Root water uptake(4) Drainage percolation(5) Photosynthesis, and(6) CO2 flux from canopy

IEM in Field Scale- Framework and Components

Modified Feddes Root Uptake Model

T

dZt,ZRht,ZRh

t,ZS rLr0

T

dZhh

t,ZS rLr0

Feddes Model

Root Density Profile Function

Modified Modified FeddesFeddes ModelModel

IEM in Field Scale- Framework and Components

IEM in Field Scale- Field Exp. And Validation

Soil and Root Profiles Sampling

IEM in Field Scale- Field Exp. And Validation

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80 100 120 140

土层深度 /cm

根长

密度

cm

/cm

3

Samples of winter wheat root

Root length density profile(CI201)

IEM in Field Scale- Field Exp. And Validation

Soil properties and parameters:

(1) Texture

(2) Retention curves

(3) Hydraulic conductivities

Soil Physics Lab, Yucheng Agri. Exp. St.

IEM in Field Scale- Field Exp. And Validation

SPAC System Observations ：(1) Soil and Root profiles

(2) Soil moisture profile and groundwater

level

(3) Transpiration by lysimeter

(4) Crop growth

(5) Meteo. factors 、 CO2 flux

(6) Leaf photosynthesis and stomata

resistance

Yucheng Agri. Exp. St.

160

140

120

100

80

60

40

20

00.0 0.1 0.2 0.3 0.4

May-6 M-R (M) Feddes (M) S-I (M)Í

Á²ãÉî¶È (cm

)0.0 0.1 0.2 0.3 0.4 0.5

ÍÁÈÀÌå»ýº¬Ë®Á¿

May -6 Feddes Feddes (M)

Comparison among soil water profiles simulated by different root uptake Comparison among soil water profiles simulated by different root uptake modelsmodels

Volumetric soil water content

Soil d

ep

th

(cm

)

IEM in Field Scale- Field Exp. And Validation

IEM in Field Scale- Field Exp. And Validation

0.00

0.10

0.20

0.30

0.40

0 20 40 60 80 100

Soil depth /cm

Vo

l. so

il w

ater

co

nte

nt

4-17(M) 4-17(S)

Comparison among soil profiles by CropS and the measured

IEM in Field Scale- Field Exp. And Validation

-2

0

2

4

6

8

10

120:0

0

6:0

0

12:0

0

18:0

0

0:0

0

6:0

0

12:0

0

18:0

0

0:0

0

Time

ET

/m

m/d

ET

BWRET

ET = 0.9673BWRET + 0.8063R2 = 0.9376

0

5

10

15

0 5 10 15

波文比法(BWRET) /mmd

(ET)

模拟

值 /

mm

/d

Comparison of ET Between CropS to Bowen Ratio Approach

Diurnal Process of ET

Correlation Analysis

IEM in Field Scale- Field Exp. And Validation

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

8:0

0

16:0

0

0:0

0

8:0

0

16:0

0

0:0

0

8:0

0

Time

CO

2 F

lux

CO2 flux calculated with Bowen Ratio approach

Comparison of CO2 fluxes by CropS and measurement

0.0

0.5

1.0

1.5

2.0

2.5

18:0

0

8:0

0

22:0

0

12:0

0

2:0

0

16:0

0

6:0

0

20:0

0

10:0

0

0:0

0

14:0

0

4:0

0

18:0

0

8:0

0

22:0

0

12:0

0

2:0

0

16:0

0

6:0

0

Time

CO

2 F

lux

CO2Flux(M)

CO2Flux(S)

IEM in Field Scale- Field Exp. And Validation

-5

0

5

10

15

0 480 960 1440 1920

Time /hours

Flu

x /m

m/d

-50

0

50

100

150

Ra

infa

ll a

nd

Irr

i. /m

mIrrigation Rainfall 100cm 200cm

Percolation processes simulated by CropS at the depths of 100cm and 200cm, respectively

IEM in Watershed Scale

MODFLOW

InterfaceSWAT

RS Info.

IEM

Eco-hydrological System

Eco-hydrological Processes Modeling in Watershed Scale

IEM in Watershed Scale

Target areas

Hetao Irrigation District

11000KM2

Panzhuang Irrigation District3300KM2

IEM in Watershed Scale

Expected Outcomes1. Dynamics of shallow groundwater table under

influence of

change of land use/cover

irrigation (diversion from Yellow river and groundwater use)

2. Effects of shallow ground water table fluctuation on

land salinization

desertification

wetland preservation(water quantity and quality)

No Conclusions

Thanks For Your Attention !