Integrated analysis of ENVISAT/RA-2 altimeter data and Landsat imagery

for estimating water volume variation of the lakes in Qiangtang Plateau

Jingjuan Liao 1, Jie Wan 1, 2 , Guozhuang Shen 1

1. Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital

Earth, Chinese Academy of Sciences, Beijing 100094, E-mail: liaojj@radi.ac.cn 2. University of Chinese Academy of Sciences, Beijing 100049

ID 10466: Applications of RA Data - Land

Outline

Background 1

2 Test Site and Datasets

3 Method

4 Results and Discussion

5 Summery and future work

Background Objectives of ID 10466: Applications of RA Data - Land

Measure the lake level changes of the Qinghai-Tibet Plateau using radar altimeter data

Measure glaciers elevation in Qinghai-Tibet Plateau using radar altimeter data

Studies carried out

Monitoring the changes of lake level and glacier elevation based on the satellite altimetry technique presented in 2014 Dragon 3 Mid-Term Results Symposium

Integrated analysis of ENVISAT/RA-2 altimeter data and Landsat imagery for estimating water volume variation of the lakes

Background The lake is an important component of the global water resources, closely

related to the survival and development of human beings.

The lakes in Qiangtang Plateau, located in the inland of Qinghai-Tibet Plateau, are hardly affected by human activities. These lakes are the indicator of climate change since they are sensitive to the change of global climate.

To investigate and analyze the lake variation in Qiangtang Plateau has very important significance on revealing the region’s climate change.

Methods of estimating lake water volume

• Water balance Equation Method1

•Bathymetric map Method 2

Background

i i D GI

o o GO

V I OI P R V VO E R V

∆ = −= + + += + +

Landsat、MODIS、CBERS

•Model for estimating water volume

Water volume variation

Lake extent change Lake level change

Method 3

• Lake extent delineation

Background

Background • Lake level extraction

Gauge site Altimetry

ICESat Envisat Cryosat2

Outline

Background 1

2 Test Site and Datasets

3 Method

4 Results and Discussion

5 Summery and future work

Test Site and Datasets Test Site

Lake distribution map Average elevation :4800m Number of lake: 500(>1km2) Main lake: Nam Co, Selin Co, Zhari Nam Co, Dangri Yum Co, Angzi Co, Zigetang Co, Daze Co

Test Site and Datasets

(1) Landsat：MSS in 1970，TM in 1990，ETM+ in 2000 (2) Envisat/RA-2： Level-2 GDR data（2002~2010）

Datasets

Outline

Background 1

2 Test Site and Datasets

3 Method

4 Results and Discussion

5 Summery and future work

Method Lake extent delineation

Method Selection of footprints within the lake

Extract the parameters for each footprint

1Hz range of each footprint

Physical corrections for 1Hz range

1Hz water level of each footprint

Daily lake level

Water level = Satellite Altitude - (Measured Range + Corrections) - geoid

• Extraction of lake level

Method

Extraction of lake extent and level

Establishing level-extent empirical model

Constructing the lake level in 1970

Estimating the water volume variation

Workflow to estimate the water volume variation

H

S2

S1

2 1 1 2 1 21 ( )*( * )3

V H H S S S S∆ = − + +

( )2 22 1 2 1

13

V h R R R Rπ∆ = + +

Increasing water volume (ΔV)

Outline

Background 1

2 Test Site and Datasets

3 Method

4 Results and Discussion

5 Summery and future work

Results and discussion Lake extent change

Year Nam Co

Selin Co

Zhari Nam Co

Dangri Yum Co

Zigetang Co

Angzi Co

Daze Co

1970 1935.9 1679.7 976.4 829.5 191.5 419.3 250.4 1990 1963.9 1763.6 961.0 829.0 200.0 388.8 250.3 2000 1981.5 1816.5 953.5 835.9 210.5 406.8 243.5 2010 2013.5 2349.2 1001.5 847.3 239.7 451.3 289.4

1970-1990 1990-2000 2000-2010 1970-2010 Variation

(km2) Variation rate(%)

Variation (km2)

Variation rate(%)

Variation (km2)

Variation rate(%)

Variation (km2)

Variation rate(%)

Nam Co 27.98 1.45 17.66 0.90 31.99 1.61 77.62 4.01 Selin Co 83.90 4.99 52.90 3.00 532.70 29.33 669.50 39.86

Zhari Nam Co -15.41 -1.58 -7.49 -0.78 48.02 5.04 25.12 2.57 Dangri Yum Co -0.51 -0.06 6.94 0.84 11.35 1.36 17.78 2.14

Zigetang Co 8.50 4.44 10.50 5.25 29.20 13.87 48.20 25.17 Angzi Co -30.50 -7.27 18.04 4.64 44.42 10.92 31.96 7.62 Daze Co -0.10 -0.04 -6.80 -2.72 45.90 18.85 39.00 15.58

Lake extents delineated from Landsat images（km2）

Lake extent variations from 1970 to 2010

Results and discussion Lake level change

Variation rate of the lakes

Lake level change of Selin Co

Results and Discussion Level-extent empirical model

Nam Co Selin Co Zhari Nam Co

Dangri Yum Co Angzi Co Zigetang Co

Daze Co

Lake Equation number R2

Nam Co H = 0.0484*S + 4629.7666 12 0.8971 Selin Co H = 0.0144*S +4514.2218 19 0.9413 Zhari Nam Co H= -0.0005*S2+ 1.113*S+ 4028 12 0.9763 Dangri Yum Co H= 0.1341*S+ 4425.55 10 0.9337 Zigetang Co H = 0.1633*S+ 4532.7184 11 0.9004 Angzi Co H = 0.0714*S + 4658.4224 11 0.9126 DazeCo H = 0.0044*S2 - 2.2727*S+4761.2245 13 0.8976

Level-extent empirical equation

Results and discussion Constructing the lake level in 1970, 1990, 2000

2002 & 2010 1970 1990 2000

Extent

(km2) Level (m) Extent Level Extent Level Extent Level

Nam Co 1996.7,

2013.5

4725.654,

4727.332 1935.9 4723.463 1963.9 4724.817 1981.5 4725.672

Selin Co 1985.3,

2349.2

4543.095,

4548.930 1679.7 4538.409 1763.6 4539.618 1816.5 4540.379

Zhari Nam

Co

962.2,

1001.5

4613.150,

4615.219 976.4 4613.868 961.0 4613.096 953.5 4612.315

Dangri Yum

Co

829.5,

847.3

4536.207,

4538.861 829.5 4536.789 829.0 4536.721 835.9 4537.651

Zigetang Co 213.2,

239.7

4566.634,

4571.709 191.5 4563.990 200.0 4565.378 210.5 4567.093

Angzi Co 420.2,

451.3

4688.021,

4690.643 419.3 4688.360 388.8 4686.183 406.8 4687.471

Daze Co 253.8,

289.4

4467.862,

4473.044 250.4 4468.021 250.3 4468.018 243.5 4467.708

Results and discussion Estimation of water volume changes

1970-1990 1990-2000 2000-2010 1970-2010 Nam Co 2.6402 1.6859 3.3161 7.6392 Selin Co 2.0798 1.3635 17.7600 21.0940

Zhari Nam Co -0.7476 -0.7482 2.8392 1.3365 Dangri Yum Co -0.0564 0.7743 1.0184 1.7373

Zigetang Co 0.1903 0.2462 0.7254 1.1629 Angzi Co -0.8797 0.5125 1.3602 0.9932 Daze Co -0.0008 -0.0766 1.4201 1.3546

Estimation of water volume variations（km3）

Water volume variations of the lake

Results and discussion

(1) Different resolutions of Landsat (MSS, TM/ETM+)

(2) Level-extent empirical model

(3) Water volume equation

Uncertainty analysis of water volume estimation

Outline

Background 1

2 Test Site and Datasets

3 Method

4 Results and Discussion

5 Summery and future work

Summery The lake extents were all enlarged in the past forty years. The lake extent

of Selin Co、Nam Co and Zigetang Co were expanding all the time, however, Angzi Co、Zhari Nam Co、Dangri Yum Co and Daze Co were firstly shrunk, then expanded. The lake extent of Selin Co increased about 669.5 km2, thus, Selin Co, exceeding Nam Co, became the largest lake in these seven lakes.

The lake levels in Qinagtang Plateau were increasing from 2002 to 2010, and Selin Co was the fastest increasing in these lakes.

By extracting the lake level and extent of the seven typical lakes, the level-extent empirical model was established, then the lake level of seven lakes in 1970 were constructed by the empirical model, and the water volume variation of seven lakes in forty years were calculated based on the model.

Future work

Extraction of lake level change in China’s main lakes using radar altimeter data Analysis of lake change, linking with

temperature, precipitation and evaporation so on Deliverables, reporting and published papers.

Published paper Jingjuan Liao, Le Gao, and Xiaoming Wang. Numerical simulation and forecasting

of water level for Qinghai Lake using multi-altimeter data between 2002 and 2012, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2014, 7(2): 609 – 622.doi: 10.1109/JSTARS.2013.2291516.

Le Gao, Jingjuan Liao, and Guozhuang Shen. Monitoring lake level changes in the Qinghai-Tibet Plateau using multi-altimeter data （2002-2012）, Journal of Applied Remote Sensing, 2013, 7(1), 073470. doi:10.1117/1.JRS.7.073470.

高乐,廖静娟,刘焕玲,郭伟.卫星雷达测高的应用现状及发展趋势, 遥感技术与应用, 2013, 28(6): 978-983.

万杰, 廖静娟，许涛，沈国状，基于ICESat高度计数据评估SRTM数据的精度-以青藏高原地区为例, 国土资源遥感, 2014, 27（1）：100-105.

廖静娟，万杰，沈国状, 基于多源遥感数据的羌塘高原典型湖泊水量变化估算研究，第19届中国遥感大会论文集，1671-1678页，西安，2014.9.21

Training of Young Scientists • Ph.D level: Gao Le • M. Sc.level: Wan Jie