Past Restoration Efforts, Techniques, Challenges ... · The function of the check dam: Control...

NORTHWEST A&F UNIVERSITY

Past Restoration Efforts, Techniques, Challenges, Successes & Future Plan

U.S.-China Exchange on Loess Landforms

Wang Li

Content

Current status of groundwater recharge

Future possible research topic4

A case study3

1 Research Background

2 Research status

6 Research plan

5

The World Loess distribution map

1 Research Background

China Loess Plateau

Loess area accounts for about 10% of global land area; The area of China Loess Plateau is 64 km2.

1 Research Background Soil and water loss in the Loess Plateau was serious, and the area

of soil erosion accounted for about 70% (47.2×104 km2) of the

total area (Yang et al., 1999); Before 1990, engineer measures contributed

54% to soil and water conservation; After

1990, vegetation restoration measures

became a major factor (57%) (Wang et al.,

2016).

Check dams Terraced fieldsFish-scale pit

2 Research status

By the end of 2016, 59 037 check dams had been built in the Loess

Plateau, including 5 829 backbone dams, 11 234 medium-sized

check dams, and 4,1974 small check dams (Hui et al., 2018).

沟道中修建的淤地坝Check dams in the gully channels

2 Research status

The function of the check dam:

Control channels erosion;

Reduce flood and sediment disasters;

Increase the farmland.

沟道中修建的淤地坝Check dams in the gully channels

2 Research status

By the end of 2012, the terraced fields area in the Loess Plateau

was 3.7 million hm2 (Ma et al., 2015).

坡地上修建的梯田Terraced fields on sloping land

2 Research status

The function of the terracing :

Reduce soil erosion;

Increase soil water content;

Increase water and nutrient use efficiency.

坡地上修建的梯田Terraced fields on sloping land

2 Research status In the much steeper slope lands and mountains, fish-scale pits

were built. And fish-scale pit has the same functions as

terraces.(Guo et al., 2017).坡地上修建的鱼鳞坑

Fish-scale pit on sloping land

2 Research status In 1999, the project of returning farmland to forests (grass) began to be implemented,

which significantly increased the vegetation cover on the Loess Plateau.

1999年 2013年

Vegetation cover change in the Loess Plateau（ Chen et al., Nature Geosci., 2015 ）

60 %32 %

Comparison of Vegetation Coverage in Hujia Village, Heijiapu, Yanchang County

1999年 2015年

2 Research status

From 2000 to 2008, the farmland decreased, and the grassland and forest land increased.

The grassland area was about 2.5 times that of the forest land and 1.3 times that of the farmland.

Land use type change in the Loess Plateau

in 2000-2008(Lü et al., Plos One, 2012)

2 Research status

0

20

40

60

80

100

120

140

1960~1969 1970~1979 1980~1989 1990~1999 2000~2009 2010~2016

流域输沙

量（亿t）

年份

The amount of sediment transportation in Toudaoguai-Tongguan

120×108 t

Changes of land use types in typical basins? The spatial and temporal changes of the NDVI in typical basins? Changes and causes of runoff and sediment transportation in

typical basins？

The variation of NDVI in the Loess Plateau in 1999-2013（Gao et al., 2017）

3 A case study

The study area is the typical basins in the northern Loess PlateauZhao QQ, Wang L*, Liu H, Zhang QF. Runoff and sediment variation andattribution over 60 years in typical Loess Plateau basins [J]. Journal of Soils andSediments, 2019, https://doi.org/10.1007/s11368-019-02345-z

3.1 Analysis on the change of land use type in typical basins3.1.1 Distribution characteristics of basins land use structure

The distribution of farmland in the KuyeRiver and WudingRiver Basins in Shaanxi Province decreased, while the distribution of grassland, forest and built-up land increased significantly. It mainly occurred in the north-central part of the Kuye River and the southeastern part of the Wuding River.

Wuding River

Kuye River

Fig. 3-1-1a The distributions of land use of typical basins in 1995, 2005 and 2015

3.1 Analysis on the change of land use type in typical basins3.1.1 Distribution characteristics of basins land use structure

Fig. 3-1-1b The distributions of land use of typical basins in 1995, 2005 and 2015

Land use change mainly occurred in the entire basin of Yanhe, especially in the northeast and the northern part of the Beiluo River.

Beiluo River

Yanhe River

3.1 Analysis on the change of land use type in typical basins3.1.2 The area of different land use types in typical basins

Fig. 3-1-2 The area of different land use types in typical basins

In the four basins, in1995, 2005 and 2015,grassland was themain type of land use(except the WudingRiver in 1995 and2005).

The area of farmlandin the four riverbasins decreased, andthe area of grasslandand forest landincreased. Theincrease in forest areawas 68.3%, 76.6%,76.9% and 10.1%.

（a）Kuye River （b）Wuding River（c）Yanhe River（d）Beiluo River

1995年 2005年 2015年0

400

800

1200

1600

2000

2400

2800

3200

面积

Area (km

2 )

年份 Year

耕地草地林地水域城乡、工矿、居民用地未利用土地

(a)

1995年 2005年 2015年0

2000

4000

6000

8000

10000

面积

Area (km

2 )

年份 Year

(b)

1995年 2005年 2015年0

1000

2000

3000

4000

面积

Area (km

2 )

年份 Year

(c)

1995年 2005年 2015年0

2000

4000

6000

8000

10000

12000

面积

Area (km

2 )

年份 Year

(d)

3.1 Analysis on the change of land use type in typical basins

3.1.2 The area of different land use types in typical basins

In the four basins in Shaanxi Province, grassland was the main land

use type in 2015.

土地利用类型Land use type

窟野河Kuye

无定河Wuding

延河Yanhe

北洛河Beiluo

耕地Farmland 1059.28 8211.11 2391.80 8540.70草地Grassland 2342.64 8551.24 3985.61 9930.03林地Forest 126.06 1617.87 1146.68 6208.72水域Water 61.66 189.01 27.28 117.55

建设用地Built-up 251.66 373.14 60.21 492.18未利用土地Unused 152.78 2905.29 28.58 23.54

Tab. 3-1-1 Land use type area of typical basins in Shaanxi Province in 2015（km2）

3.2 Temporal and spatial variability of typical basins NDVI3.2.1 Distribution of NDVI status of typical basins in 2000, 2010 and 2018

The NDVI of the Kuye River and the Wuding River Basin during the vigorous growth period was increase. From the perspective of spatial distribution, it was mainly in the north of the Kuye River and southeast of the Wuding River.

Kuye River

Wuding River

Fig. 3-2-1a Distribution of NDVI status of typical basins in 2000, 2010 and 2018

3.2 Temporal and spatial variability of typical basins NDVI3.2.1 Distribution of NDVI status of typical basins in 2000, 2010 and 2018

Fig. 3-2-1b Distribution of NDVI status of typical basins in 2000, 2010 and 2018

From the perspective of spatial distribution, the NDVI in the Yanhe and BeiluoRiver basins were mainly in the northeastern part of the Yanhe River and the northern part of the Beiluo River.

Yanhe River

Beiluo River

3.2 Temporal and spatial variability of typical basins NDVI3.2.2 Area percentage of different levels of NDVI in typical basins

2000年 2010年 2018年0%

20%

40%

60%

80%

100%

ND

VI

分级组成

ND

VI g

radi

ng c

ompo

sitio

n (%

)

年份 Y ear

≤0 (0,0.3] (0.3,0.5] (0.5,0.7] (0.7,1.0]

(a)

2000年 2010年 2018年0%

20%

40%

60%

80%

100%

ND

VI

分级

组成

ND

VI g

radi

ng c

ompo

sitio

n (%

)年份 Y ear

(b)

2000年 2010年 2018年0%

20%

40%

60%

80%

100%

ND

VI

分级

组成

ND

VI g

radi

ng c

ompo

sitio

n (%

)

年份 Y ear

(c)

2000年 2010年 2018年0%

20%

40%

60%

80%

100%

ND

VI

分级

组成

ND

VI g

radi

ng c

ompo

sitio

n (%

)

年份 Y ear

(d)

Fig. 3-2-2 Area percentage of different levels of NDVI in typical basins

The NDVI of the four basins area in the (0,0.3] were continuous reduction. The largest decrease was the KuyeRiver Basin.

The NDVI of the four basins with the high vegetation coverage area in the (0.7,1] were increase. The largest increase was the YanheRiver Basin.

3.2 Temporal and spatial variability of typical basins NDVI3.2.4 Annual average NDVI variation from 2000 to 2016 in typical basins

2000 2002 2004 2006 2008 2010 2012 2014 2016

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

ND

VI

年份 Year

(a)

y=0.0069x-13.79R2=0.903

2000 2002 2004 2006 2008 2010 2012 2014 2016

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

ND

VI

年份 Year

(b)

y=0.006x-11.915R2=0.95

2000 2002 2004 2006 2008 2010 2012 2014 2016

0.20

0.24

0.28

0.32

0.36

0.40

0.44

ND

VI

年份 Year

(c)

y=0.009x-18.027R2=0.889

2000 2002 2004 2006 2008 2010 2012 2014 2016

0.36

0.38

0.40

0.42

0.44

0.46

0.48

0.50

N

DV

I

年份 Year

(d)

y=0.0043x-8.193R2=0.762

Fig. 3-2-4 Annual average NDVI variation from 2000 to 2016 in typical basins

From 2000 to 2016, the annual NDVI of the four basins showed an increasing trend (P<0.01), with annual growth rate of 0.7%, 0.6%, 0.9%, and 0.4%, respectively. The largest rate was Yanhe.

3.3 Changes in runoff and sediment transportation in typical basins and their responses to NDVI

3.3.1 Annual runoff and sediment trends in typical basins

3.3.1.1 Annual runoff trends in typical basins

1960 1970 1980 1990 2000 2010 20200

2

4

6

8

10

12

14

径流量

Annual runoff discharge (108m3)

年份 Year

径流量每10年径流量均值

(a)

1960 1970 1980 1990 2000 2010 20204

6

8

10

12

14

16

18

20

22

径流量

Annual Runoff discharge(108m)

年份 Year

(b)

1960 1970 1980 1990 2000 2010 20200

1

2

3

4

5

6

径流量


年份 Year

(c)

1960 1970 1980 1990 2000 2010 20200

2

4

6

8

10

12

14

16

18

20

22

径流量


年份 Year

(d)

The runoff of the four

basins showed a

significantly decreasing

trend from 1960 to 2016.

Fig. 3-3-1 Annual runoff trends in typical basins


3.3.1.2 Annual sediment trends in typical basins

1960 1970 1980 1990 2000 2010 2020

0

1

2

3

4

5 输沙量每10年输沙量均值

输沙量

Annual sediment discharge (108t)

年份 Year

(a)

1960 1970 1980 1990 2000 2010 2020

0

1

2

3

4

5

输沙量


年份 Year

(b)

1960 1970 1980 1990 2000 2010 2020

0

1

2

输沙量


年份 Year

(c)

1960 1970 1980 1990 2000 2010 20200

1

2

3

输沙量


年份 Year

(d)

The sediment

transportation of the four

basins showed a

significantly decreasing

trend from 1960 to 2016.

Fig. 3-3-2 Annual sediment trends in typical basins


3.3.2 Anomaly accumulations for runoff and sediment volume in typical basins

1960 1970 1980 1990 2000 2010 20200

20

40

60

径流量累积距平输沙量累积距平

年份 Year

径流量累积距平

Runo

ff a

ccum

ulat

ion

anom

aly

(108 m

3 )

(a)

1979

1996

0

2

4

6

8

10

12

14

16

输沙量累积距平

Sedi

ment

acc

umul

atio

n an

omal

y (1

08 t)

1960 1970 1980 1990 2000 2010 20200

20

40

60

年份 Year


Runo

ff a

ccum

ulat

ion

anom

aly

(108 m

3 )

(b)

1979

1996

0

2

4

6

8

10

12

14


Sedi

ment

acc

umul

atio

n an

omal

y (1

08 t)

1960 1970 1980 1990 2000 2010 20200

10

20

30

40

50

年份 Year


Runo

ff a

ccum

ulat

ion

anom

aly

(108m3 )

(d)

1994

0

2

4

6

8


Sedi

ment

acc

umul

atio

n an

omal

y (1

08t)

1979

2001

The pivotal

points for the

basins of the

three rivers Kuye,

Wuding and

Yanhe were all in

1979 and 1996.

In the Beiluo

River basin, the

fluctuations were

relatively

complex.Fig. 3-3-3 Anomaly accumulations for runoff and sediment volume in typical basins

1960 1970 1980 1990 2000 2010 2020

0

2

4

6

8

10

年份 Year

径流

量累

积距

平

Runoff accumulation anomaly (108m3)

(c)

1979

1996

0

1

2

3

4

5

输沙

量累

积距

平

Sediment accumulation anomaly (108t)


3.3.3 Precipitation-runoff and precipitation-sediment accumulation in typical basins

0 5 10 15 20 250

50

100

150

200

250

300量

累积径流累积输沙量

累积降水量Accumulated precipitation (m)

累积

径流

量

Accumulated runoff (108m3)

0

10

20

30

40

1996

累积

输沙

量

Accumulated sediment (108t)

(a)

1979

0 5 10 15 20 250

100

200

300

400

500

600

700

800


累积

径流

量


0

10

20

30

40

50

60

累积

输沙

量


(b)1979

1996

0 5 10 15 20 25 30 350

20

40

60

80

100

120


累积

径流

量


0

10

20

30

40

累积

输沙

量


(c)

1979

1996

0 5 10 15 20 25 30 35 400

50

100

150

200

250

300

350


累积径流量


0

10

20

30

40

累积输沙量


(d)1979

2001

1994

In the KuyeRiver, WudingRiver and YanheRiver basins, both curves shifted at 1979 and 1996.

In Beiluo River basin shifted at 1979 and 1994. and the 1979 and 2001.

Fig. 3-3-4 Precipitation-runoff and precipitation-sediment accumulation in typical basins


3.3.5 Effects of precipitation and human activities on runoff and sediment

1970 1980 1990 2000 2010 2020-10

-8

-6

-4

-2

0

2

4

6

年份 Year

影响

径流

量

Influ

ence

d ru

noff

(108 m

3 )

人类活动对径流量的影响降水对径流量的影响

(a)

1970 1980 1990 2000 2010 2020-10

-8

-6

-4

-2

0

2

4

年份 Year

影响径流量

Influ

ence

d ru

noff

(108 m

3 )

(b)

1970 1980 1990 2000 2010 2020-2

0

2

年份 Year

影响

径流

量

Influ

ence

d ru

noff

(108 m

3 )

(c)

1970 1980 1990 2000 2010 2020-8

-6

-4

-2

0

2

4

6

年份 Year

影响径流量

Influ

ence

d ru

noff

( 108 m

3 )

(d)

For the Kuye and Wuding River basins, it can be seen that during the entire period of 1970–2016, human activities played a major role in reducing runoff. The impact of human activities was 2.77×108 m3

and 4.45×108 m3, respectively.

In the Yanhe and Beiluo River basins, precipitation obviously contributed to the reduction in runoff, with an impact on runoff of 0.61×108

m3 and 2.09×108

m3, respectively.Fig. 3-3-6 Effects of precipitation and human activities on

runoff in typical basins

3.3.5.1 Effects of precipitation and human activities on runoff in typical basins


3.3.5.1 Effects of precipitation and human activities on sediment in typical basins

1970 1980 1990 2000 2010 2020-3

-2

-1

0

1

2

年份 Year

影响

输沙

量

Influ

ence

d se

dim

ent (

108 t)

人类活动对输沙量的影响降水对输沙量的影响

(a)

1970 1980 1990 2000 2010 2020-3

-2

-1

0

1

2

年份 Year

影响

输沙

量

Influ

ence

d se

dim

ent

(108 t)

(b)

1970 1980 1990 2000 2010 2020-1.0

-0.5

0.0

0.5

1.0

年份 Year

影响

输沙

量

Influ

ence

d se

dim

ent

(108 t)

(c)

1970 1980 1990 2000 2010 2020-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

年份 Year

影响

输沙

量

Influ

ence

d se

dim

ent (

108 t)

(d)

In Kuye and WudingRiver, in 1970-2016, human activities contributed significantly to the reduction in sediment discharge, the impact being 0.56×108 t and 0.97×108 t, respectively.

In Yanhe and BeiluoRiver, precipitation contributed significantly to the reduction in sediment discharge from 1970 to 2016. The impact on sediment discharge was 0.25×108 t and 0.35×108 t, respectively.

Fig. 3-3-7 Effects of precipitation and human activities on sediment transportation in typical basins


As the NDVI increasing, the runoff in the basins decreased. In Yanhe River and Beiluo River, the NDVI were increasing, but the runoff in

four basins were decreasing, the negative correlation between them were poor.

3.3.6 Trends of NDVI and runoff in typical basins

2000 2002 2004 2006 2008 2010 2012 2014 20160

2

4

6

径流量 NDVI

年份 Year

径流

量

Run

off (

10

8 m3 )

(a)

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

NDVI

2000 2002 2004 2006 2008 2010 2012 2014 20164

6

8

10

12

年份 Year

径流

量

Run

off (

10

8 m3 )

(b)

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

NDVI

2000 2002 2004 2006 2008 2010 2012 2014 20160

2

4

年份 Year

径流

量

Run

off (

10

8 m3 )

(c)

0.1

0.2

0.3

0.4

0.5

NDVI

2000 2002 2004 2006 2008 2010 2012 2014 2016

4

6

8

10

12

14

年份 Year

径流量 R

unof

f (10

8 m3 )(d)

0.30

0.35

0.40

0.45

0.50

NDVI

Fig. 3-3-8 Trends of NDVI and runoff in typical basins

The trend of average annual NDVI in the four typical basins were negative relationship with the trend of annual average sediment transportation. This shown that vegetation restoration was conducive to the reduction of sediment transportation.


2000 2002 2004 2006 2008 2010 2012 2014 20160.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20 输量沙 NDVI

年份 Year

输沙量

Sediment (10

8 t)

(a)

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

NDVI

2000 2002 2004 2006 2008 2010 2012 2014 20160.0

0.2

0.4

0.6

0.8

1.0

1.2

年份 Year

输沙量

Sediment (10

8 t)

(b)

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

NDVI

2000 2002 2004 2006 2008 2010 2012 2014 20160.0

0.2

0.4

0.6

0.8

年份 Year

输沙量

Sediment (10

8 t)

(c)

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

NDVI

2000 2002 2004 2006 2008 2010 2012 2014 20160.0

0.2

0.4

0.6

0.8

1.0

1.2

年份 Year

输沙量

Sediment (10

8 t)(d)

0.30

0.35

0.40

0.45

0.50

NDVI

3.3.7 Trends of NDVI and sediment transportation in typical basins

Fig. 3-3-9 Trends of NDVI and sediment transportation in typical basins


3.3.8 Conclusion

The runoff and sediment transportation of the four basins showed a

significantly decreasing trend from 1960 to 2016.

The changes in sediment discharge were influenced by precipitation and

human activities. Compared with precipitation, human activities within the

more northerly Kuye and Wuding River basins have played a more

prominent role in the changes in sediment regimes. For the more southerly

Yanhe and Beiluo River basins, throughout the research period, the effect of a

reduction in precipitation on the runoff and sediment discharge has been

greater than the effect of human activities.

The trend of average annual NDVI in the four typical basins were negatively

related with the trend of annual average sediment transportation.

4 Future possible research topicWhat are the scientific issues that the Loess

Plateau really needs to study?（1）Soil erosion: many studies（2）Vegetation restoration: many studies（3）Runoff and sediment changes: many studies

Two important scientific questions:（1）Why natural forest vegetation exists only in loess and rock

mountains?（2）Recharge route and mechanism of groundwater in thick

layer loess area?

0

2

8

20

50

100 Δ

2：Contribution of deep soil water to vegetation transpiration and ratio of groundwater recharge？

Deep(m)

Deep soil

1：Movement mechanism and flux of deep soil water under deep soil conditions？

How does precipitation recharge groundwater through thick loess?

Vegetation growth and groundwater level decline

11.41.82.22.63

0.250.270.290.310.33

1979 1984 1989 1994 1999 2004 2009 2014

NDVI

NDVI

Runoff

(×

108m3yr-1)

降水

量（

0

400

800

1976 1984 1992 2000 2008

地下

水位

（m）

24

26

28

30

32降水水位

Groundwater

level（

m）

2006

6 m

1990

Rainfall (mm)

年份

Possible effects on groundwater recharge after extensive vegetation increase

Deep soil

Shallow soil

Parent material Deep leakage

• Average rainfall infiltration depth

• Contains 90% root system• More large pores and

good water conductivity• depth：1-4 m

• 10% root system• Poor water conductivity• depth：2-20 m

补

Rainfall infiltration soil recharges groundwater

5 Research Status of Groundwater Recharge in the Loess Plateau

5.1 Recharge source（1）Rainfall (most scholars)

（2）Exogenous water (Chen et al., 2017)

Groundwater in the Qinghai-Tibet Plateau is recharged through underground passages


5.1 Recharge source

Magmatic activity and volcanic eruption caused by collision between Indian plate and Eurasian plate

（1）Rainfall (most scholars)

（2）Exogenous water (Chen et al., 2017)

Qinghai-Tibet PlateauOrdos block Taihang

Changbai

High Conductivity and Low Velocity Layer at Crust-Mantle Junction

Loess Plateau

Macropore

5.2 Recharge mechanism

Large pore dominant flow

Medium pore rapid plug flow

Small pore slow plug flow

Total flux

Bright blue staining亮蓝染色法

Isotope and Cl-

substitution

Tracer and large, medium and small pore flow


(1) Piston flow - thick layer aeration zone

(2) Preferential flow - large pores, holes,

cracks.

5.3 Research method


chloride concentration

(1)Chlorine mass balance method; (2)Tritium Peak Method;(3)Stable isotope method; (4)Thermal tracer method; (5)Model simulation

Chloride ion in the environment has high solubility and stability, and can migrate with water molecules in the vadose zone. When water is evaporated, chlorine is retained in the vadose zone, and its concentration and amount of water consumed by evapotranspiration In direct proportion.

5.3 Research method

3H distribution of soil profiles at different slope positions

Tritium content(TU)

0 20 40 60

Dep

th(m

)

0

5

10

15

20

upper middle lower

上坡

中坡

下坡

氚含量(TU)


(1)Chlorine mass balance method; (2)Tritium Peak Method ;(3)Stable isotope method; (4)Thermal tracer method; (5)Model simulation

Assume that the depth of the peak in the aeration zone in 1963 is S[L], the sampling time is t years, and the average volumetric water content of soil above D is θ, then the recharge amount R[LT-1] is:

𝑅𝑅 = 𝑆𝑆 � 𝜃𝜃/（𝑡𝑡 − 1963）

5.3 Research method5 Research Status of Groundwater Recharge in the Loess Plateau


Oxygen isotope water source division

The isotope composition of precipitation changes with the seasons, and the winter is low in summer. This seasonal variation can be reflected in the recharge water, which can be used to estimate the recharge of groundwater. By comparing the stable isotope characteristics of precipitation and groundwater, it can be determined whether groundwater is derived from atmospheric precipitation.

5.3 Research method5 Research Status of Groundwater Recharge in the Loess Plateau

Drilling fiber sensor layout diagram

Some scholars have found that the temperature distribution of the past climate deviates from the steady state. In the thick vadose zone, the magnitude of the deviation represents the recharge intensity, which can be used as a tracer to estimate groundwater recharge.

Most hydrological models include groundwater modules that can be used to simulate groundwater recharge based on the principle of water balance.


5.4 Recharge amountNumber research area Method Rainfall(mm) Recharge(mm) 文献

1Hilly and gully regions of Loess

Plateau/Zhifanggou watershed/AnsaiChlorine mass balance method /

stable isotope method500 55-90 Gates et al. (2011)


Plateau/Hequanhe watershed/GuyuanChlorine mass balance method /

stable isotope method450 50-100 Huang et al. (2013)

3Loess-sand/Wudan Town/Inner Mongolia

Wengniute BannerTritium Peak Method 360 47 Lin and Wei (2006)


Plateau/Pingding County/YangquanTritium Peak Method 550 68 Lin and Wei (2006)

5Hilly and gully regions of Loess Plateau/Xifeng Plateau/Qingyang

Chlorine mass balance method 523 33 Huang and Pang (2011)


Plateau/Changwu Plateau/ChangwuSHAW Model simulation 545 9.3-18.3

Huang and Gallichand(2006)


Plateau/Luochuan Plateau/LuochuanCoupModel Model simulation 568 17 Zhang et al. (2007)


Plateau/Heihe watershed/ChangwuChlorine mass balance method /

stable isotope method584 107 Li et al. (2017)


Plateau/Wuding River Basin/SuideMRC Curve simulation 409 11.4~15.7 Zhu et al. (2010)


Plateau/Chabagou watershed/SuideMRC Curve simulation 480 1.5-15.1 Ma et al. (2018)

11Gully area of the Loess Plateau/Wangdonggouwatershed/Changwu

Tritium Peak Method 584 20-27 Li et al. (2016)

12Hilly and gully regions of Loess Plateau/Yangou watershed/Xi’an

CoupModel Model simulation 537 37 Wang et al. (2012)


5.5 Problem（1）Whether it is the source of replenishment, the replenishment path, or the replenishment mechanism, the current research conclusions are vastly different and there is no unified understanding.（2）The depth of research is shallow and it is difficult to reflect the actual situation of thick layer of loess.（3）The replenishment mechanism remains unclear and the current conclusions have not been widely recognized by the academic community.（4）Research methods need to be expanded.

5.6 Research content（1）What is the chloride ion characteristics and groundwater recharge history of thick layer loess profiles?（2）What is the dynamic variation characteristics of groundwater in thick loess area and its influencing factors?（3）Analysis on the ways and process of recharge of groundwater in thick loess area?（4）Effects of land use change on deep seepage and groundwater recharge in thick layer loess?（5）Simulation and mechanism analysis of groundwater recharge in thick loess area?


∆𝑺𝑺= R-T-D

Shallow soil

Deep soil

Rootless soil

Groundwater

（R）(T)

6 Research plan

Deep soil water supply mechanism

Soil water absorption deep roots to deep layers

Deep leakage

（D）

6 Research plan

6.1 Sample Layout

loess Liang/Mao area

loess Yuan/Valley

Platform

River

6 Research plan6.1 Sample Layout

Loess Plateau

Vertical section of thick yellow soil layer(Taking Luochuan Tableland as an example)

Xifeng Tableland

6 Research plan

Malan Loess

Upper part of Lishi loess

Lower part of Lishi loess

Wucheng Loess

黄土芯剖面Loess core profile

Loess Mao-small hill

6 Research plan

Lishi Loess

6.1 Sample Layout

Malan Loess

Wucheng Loess

Shallow groundwater

Deep groundwater

Lishi Loess

Loess Yuan-Loess tableland

6 Research assumption6.1 Sample Layout

Malan Loess

Lishi Loess

Wucheng Loess

Deep groundwater

钻探探测

水泥粘土填充Cement clay filling

同时钻探、取样、测量水文特性Simultaneous drilling, sampling, and measurement of hydrological characteristics

液气平衡原位抽提Liquid-gas equilibrium in-situ extraction

同位素注入Isotope inject

亮蓝注入Bright blue inject

大型观测取样井Large observation sampling well

含水量、水势高频监测Water content, water potential high frequency monitoring

6.2 Research plan-Deep soil hydrological characteristics and determination method of groundwater recharge process

Drilling detection

Past Restoration Efforts, Techniques, Challenges ... · The function of the check dam: Control...

Documents

Transcript of Past Restoration Efforts, Techniques, Challenges ... · The function of the check dam: Control...