International Meeting on Land Use and Emissions in South/Southeast AsiaHo Chi Minh City, 17-19 October 2016

Land use change and rice crop monitoring in the Mekong Delta, Vietnam

Nguyen Lam-Dao, Phung Hoang-Phi VN Southern Satellite Technology Application Center (STAC)–VNSC–VAST

Thuy Le-ToanCentre d'Etudes Spatiales de la BIOsphère (CESBIO), France

Viet Pham-Bach, Mai Thy Pham-ThiGIS and Remote Sensing Research Center (GIRS)–HCMIRG–VAST

1. Introduction

2. Land use change in the Mekong Delta, Vietnam

3. Rice crop monitoring

4. Discussion

Contents

2

INTRODUCTION

Source: Parry, M.L. et al., 2007

3

2012

Mekong Delta (Source: GSO, 2015): Area: 40,576 Km2 (1/8) Population: 17.590 M (~1/5) MD accounts for more than half (25.7 / 45.2 Mt)

of the country’s rice production (>1/2)

The Mekong Delta, South of Vietnam is one of the most affected regions in the world by global warming.

4

LAND USE CHANGE - Introduction

State-level project (2013-2016): Utilisation of satellite imagery VNREDSat-1 and equivalent for monitoring agricultural land cover/land use of the Mekong Delta, Vietnam in the context of socio-economic development and climate change.

VNREDSat-1 (7 scenes) and Landsat data used

5

LAND USE CHANGE - Introduction

Landsat 7, 20/01/2005

Landsat 8, 27/2/2014

Landsat 5, 21/2/1996

6

LAND USE CHANGE - Introduction

Field work: collecting 1.089 samples,

70% for training data; 30% for accuracy assessment.

1st field trip (6 -16/1/2014) 2nd field trip (11 - 17/4/2014)

7

1996

2005

2014Overall Acc.: 80 %

Kappa: 0,75

LAND USE CHANGE – Results from Landsat

8

LAND USE CHANGE - Results from Landsat

1996-2005 2005-2014 1996-2014

9

LAND USE CHANGE - Results from Landsat

Agricultural land use was changed in the period of 1996 – 2005 – 2014;

Rice and aquaculture land fast increasedduring the period of 1996 – 2005;

10

LAND USE CHANGE – Results from VNREDSat-1

LU change – Ricein Thoai Son, An Giang (1998-2015)

LU change – Fruit treein Cai Be, Tien Giang (1995-2015)

11

LAND USE CHANGE - Results from VNREDSat-1

LU change – Forestin Tram Chim, Dong thap (1995-2015)

LU change – Aquaculturein Vinh Chau, Soc Trang (1996-2015)

12

Wetland map of Lower Mekong basin (2015)

RICE CROP MONITORING - Introduction

Ongoing projects1. SAFE/APRSAF (2013-2016) &Asia-RiCE2. GeoRice (2015-2017) Data used: COSMO-SkyMed, RADARSAT-2,

ALOS-2, Sentinel-1.

13

Previous projects1. Rice & Mangrove monitoring in Southern Vietnam

- RICEMAN TerraSAR-X & ENVISAT-ASAR data, 2010-2011 Rice mapping: Single-date mapping algorithm Yield estimation model: Statistical model.

2. Rice crop monitoring using new generation synthetic aperture radar (SAR) imagery

ENVISAT-ASAR data, 2007-2008 Rice mapping: Single-date mapping algorithm Yield estimation model: Statistical model.

3. Utilisation of SAR data for rice crop monitoring ERS2-SAR data, 1997-1998 Rice mapping: Temporal change measurement Yield estimation model: Agro-meteorological model

(AMM).

4. Other projects in the Mekong and Red River Delta

Introduction

Sowing-transplanting period

Reproductive stage

Vegetative stage

Ripening stagePictures of rice growing stages

14

Main rice-based cropping systems in the MD

Rice cropping system Rice season

Single rice crop Traditional rice (rain-fed)

Double rice crop SA – AW (rain-fed)

WS – SA (irrigated)

Triple rice crop WS – SA - AW

Main rice seasons in An Giang province, Mekong Delta

Rice crop Planting Harvesting

English name Local name

Winter Spring (WS) Dong Xuan Nov./Dec. Mar./Apr.

Summer Autumn (SA) He Thu Apr./May Jul./Aug.

Rainy season Thu Dong (Autumn Winter-AW) Jul./Sep. Oct./Dec.

Mua (Traditional rice) Jul./Sep. Nov./Jan.

Introduction

24/03/0717/02/2007

Objectives:

To evaluate the use of SAR data in rice mapping, monitoringand yield estimation, towards an operational system for rice crop inventory in the Mekong Delta, Vietnam.

15

Ongoing research works – Asia-RiCE&SAFE, GEORice

16

Technical Demonstrator Site – Mekong Delta, VN

An Giang province, Mekong Delta, Vietnam Geographic coordinates:

UL: 10°58'47.38"N, 104°44'39.51"E, UR:10°58'35.84"N, 105°40'12.84"E

LR: 10°05'24.65"N, 105°40'15.36"E,LL: 10°05'45.13"N, 104°44'23.41"E

Methods

24/03/07

17

SAR data

σo of sampling fieldsGround-truth data

In situ rice yield Regression analysis• Regression equation

Estimated rice yield distribution maps

Estimated rice production (P5)

Rice/Non-rice maps (P1)

Classification method• Thresholding

Classification maps

Accuracy assessment• Reference data• Ground dataAsia-RiCE Target Agricultural Products

Data set

18

SAR data received:COSMO-SkyMed: Aug 2013 – Feb 2014RADARSAT-2: Aug 2013 – NowSentinel-1: Aug 2014 – NowALOS-2: Nov 2014 – Now

Rice crops monitored:2013: AW; 2014-2016: WS, SA, AW.

COSMO-SkyMed data:- Band: X- Polarisation: HH&VV- Resolution: 20 m (StripMap PINGPONG)

RADARSAT-2 data:- Band: C- Polarisation: VV&VH- Resolution: 10 m (Wide Fine)

Sentinel-1 data:- Band: C- Polarisation: VV&VH- Resolution: 20 m (SW)

ALOS-2 data:- Band: L- Polarisation: HH&HV- Resolution: 50 m (WS) & 12.5 m (Fine)

Sentinel-16 October 2014

Data set: CSK & RSAT-2, 2013-2014

19

Rice parameters Description Equipment

General parameters

Paddy variety Ex.: IR 64Method of planting direct sowing/ transplanting

Sowing date date of direct sowing or number of days after sowing

Transplanting date(if transplanting)

date of transplantation or the number of days after transplantation

Date of harvesting if the rice has been harvested

Yield (kg/m2) if the rice have been harvested

Plant phenological stageSeeding, transplanting, tillering, heading, flowering, ripening, ready to harvest

Water layer height (cm) if fields are flooded stickPlant height (cm) above water layer tape

Wet weight per m2(g) above water biomass (moist weight by m2)

cut all plants from defined areas (min 50 x 50 cm)

Dry weight per m2 (g) objective is to measure the dry biomass per m2

Oven dry (105°during 24 hours)

Leaf parameters(optional)

Number of leaves per stem Few samples for each sortie

Leaf length (cm)Leaf width (cm)

-Photo-Xerox copy of leaves

Panicle parameters Moist and dry biomass of panicles per m2

Guidelines for ground data collection for rice monitoring experiments using radar data(Thuy Le Toan)

-10.0

-5.0

0.0

5.0

10.0

15.0

0 10 20 30 40 50 60 70 80 90 100 110

HH/V

V (d

B)

Ngày sau khi sạ

CSK_PP_20130819

CSK_PP_20130904

CSK_PP_20130920

CSK_PP_20131006

CSK_PP_20131014

CSK_PP_20131030

CSK_PP_20131107

CSK_PP_20131115

Data set: CSK, 2013-2014

20

Days after sowing

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 10 20 30 40 50 60 70 80 90 100 110

Số ngày sau sạ/cấy

HH

/VV

(dB

)

TĐ2010_CMĐX2011_CMĐX2011_TL

-4

-2

0

2

4

6

8

10

0 20 40 60 80 100

Days after sowing

HH

/VV

(dB

)

WS SA AW WS0 SA0 AW0

TSX (2010-11)ASAR APP(2007)

CSK (2013)

Data set: CSK, 2013-2014

21

WS 2014 crop from CSK PP (11 Feb 2014)

AW 2013 crop from CSK PP (20 Sep and 14 Oct 2013)

Overall acc.: 89%Kappa: 0.77

Data set: CSK, 2013-2014

22

Commune Name Estimated area (ha)

Agency data (ha)

Percentage error (%)

An Bình 2,274 2,287 -0.6

Bình Thành 2,313 2,325 -0.5

Định Mỹ 3,178 2,965 7.2

Định Thành 2,613 2,454 6.5

Mỹ Phú Đông 2,676 2,740 -2.3

Phú Thuận 1,131 835 35.4

Thoại Giang 2,203 2,248 -2.0

Núi Sập 455 442 2.9

Óc Eo 522 592 -11.8

Phú Hòa 294 310 -5.2

Vĩnh Khánh 2,500 2,810 -11.0

Vĩnh Phú 3,069 3,153 -2.7

Vĩnh Trạch 1,269 1,424 -10.9

Vĩnh Chánh 2,357 1,996 18.1

Vọng Đông 2,601 2,096 24.1

Total 29,455 28,677 2.7

Accuracy assessment of rice/non-rice mapping method for AW 2013 crop in Thoai Son district using two-date CSK data (20 Sep and 14 Oct) based on statistical data

y = 0.9639x + 18.956R² = 0.9511

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0 500 1,000 1,500 2,000 2,500 3,000 3,500

Agen

cy d

ata

(ha)

Estimated area (ha)

Data set: CSK, 2013-2014

23AW 2007 crop from

ASAR APPAW 2013 crop from

CSK PPAW 2010 crop from

ASAR APP

Data set: CSK, 2013-2014

24

YRa = 6.66696 – 0.483956*Ra1 – 0.284715*Ra2 + 0.641779*Ra3r2 = 0.646, sey = 0.5 ton/haWhere:

YRa : rice yield (ton/ha),Ra1 : polarisation ratio of first date image,Ra2 : polarisation ratio of second date image,Ra3 : polarisation ratio of third date image,r2 : the coefficient of determination,sey : the standard error for the y estimate.

A distribution map of estimated rice yield in AW 2013 crop at Chau Thanh and Thoai Son districts using three-date polarisation ratios:• CSK 04 Sep 2013 • CSK 22 Oct 2013• CSK 07 Nov 2013

Data set: CSK, 2013-2014

25

Accuracy assessment of estimated productionfor AW 2013 crop at Chau Thanh and ThoaiSon district using three-date polarisation ratios(HH/VV) of CSK (04 Sep, 22 Oct, 07 Nov 2013)based on statistical data

y = 0.9788x + 181.2R² = 0.9429

0

5000

10000

15000

20000

25000

0 5000 10000 15000 20000 25000Es

timat

ed p

rodu

ctio

n (t

on)

Agency data (ton)

Chau Thanh

Thoai Son

Commune nameEstimated

production (ton)

Agency data (ton)

Percentage error (%)

Vinh Thanh 11,655 11,382 2.4Vinh Nhuan 19,097 18,640 2.5Vinh Loi 12,620 13,229 -4.6Hoa Binh Thanh 13,539 14,797 -8.5TT. An Chau 2,744 3,472 -21.0Binh Hoa 7,076 6,852 3.3Vinh Binh 14,220 12,565 13.2Vinh Hanh 14,653 15,188 -3.5Can Dang 12,688 12,973 -2.2An Hoa 3,048 2,679 13.8Binh Thanh 14,028 13,225 6.1Dinh My 19,492 17,668 10.3Dinh Thanh 14,951 14,157 5.6My Phu Dong 15,114 18,056 -16.3Phu Thuan 4,961 5,684 -12.7Thoai Giang 13,865 13,025 6.4TT. Nui Sap 2,905 2,495 16.4TT. Oc Eo 3,390 3,297 2.8TT. Phu Hoa 1,436 1,614 -11.0Vinh Khanh 14,432 16,357 -11.8Vinh Phu 18,541 19,735 -6.1Vinh Trach 7,404 8,975 -17.5Vinh Chanh 11,538 12,333 -6.4Vong Dong 16,158 12,551 28.7Total 269,555 270,949 -0.5

Data set: RADARSAT-2, 2013-2014

26

RADARSAT-2 data:- Band: C- Polarisation: VV&VH- Resolution: 10 m (Wide Fine)

Data set: RADARSAT-2, 2013-2014

27

AW 2013 crop from RADARSAT-2 (29 Aug & 09 Nov 2013)

AW 2013 crop from CSK PP (20 Sep & 14 Oct 2013)

Data set: RADARSAT-2, 2013-2014

28

Commune name Estimated area (ha)

Agency data (ha)

Percentage error (%)

An Binh 2,422 2,287 5.9Binh Thanh 2,316 2,325 -0.4Đinh My 3,274 2,965 10.4Đinh Thanh 2,743 2,454 11.8My Phu Đong 2,828 2,740 3.2Phu Thuan 326 835 -61.0Tay Phu 1,936 2,386 -18.9Thoai Giang 2,349 2,248 4.5Nui Sap 481 442 8.8Oc Eo 507 592 -14.4Phu Hoa 99 310 -68.1Vinh Khanh 2,545 2,810 -9.4Vinh Phu 3,213 3,153 1.9Vĩnh Trach 1,303 1,424 -8.5Vinh Chanh 1,530 1,996 -23.3Vong Đong 2,620 2,096 25.0Vong The 2,383 2,300 3.6Total 32,875 33,363 -1.5

y = 0.8439x + 330.44R² = 0.9324

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0 500 1,000 1,500 2,000 2,500 3,000 3,500

Agen

cy d

ata

(ha)

Estimated area (ha)

RADARSAT-2, Thoai Son District - AW2013

Accuracy assessment of rice/non-rice mapping method for AW 2013 crop in Thoai Son district using two-date RADARSAT-2 data (29 Aug & 9 Nov 2013) based on statistical data

Data set: RADARSAT-2, 2016

29

SA 2016 crop from RADARSAT-2 (15 Apr, 09 May, 02 Jun, 26Jun, 20 Jul & 13 Aug)

District Agency data (ha)

Estimated area (ha)

Difference percentage

(%)An Phu 13,640 13,679 0.3Cho Moi 13,304 14,784 11.1Chau Phu 34,940 30,274 -13.4Chau Thanh 28,630 26,857 -6.2Phu Tan 22,151 23,382 5.6Tinh Bien 16,288 21,000 28.9Chau Doc 6,315 6,218 -1.5Long Xuyen 4,518 3,427 -24.1Thoai Son 38,882 37,236 -4.2Tri Ton 42,210 38,042 -9.9Tan Chau 9,321 9,874 5.9Total 230,199 224,774 -2.4

R² = 0.97

0

10,000

20,000

30,000

40,000

50,000

0 10,000 20,000 30,000 40,000 50,000

Estim

ated

are

a (h

a)

Agency data (ha)

30

A distribution map of estimated rice yield in AW 2013 crop at Chau Thanh and Thoai Son district using three-date VH polarisation: RADARSAT-2 29 Aug 2013 RADARSAT-2 16 Oct 2013 RADARSAT-2 09 Nov 2013

A distribution map of estimated rice yield in WS 2014 crop at Chau Thanh and Thoai Son district using three-date VH polarisation: RADARSAT-2 27 Dec 2013 RADARSAT-2 20 Jan 2014 RADARSAT-2 13 Feb 2014

Data set: RADARSAT-2, 2013-2014

31

Data set: RADARSAT-2, 2013-2014

A distribution map of estimated rice yield of An Giangin AW 2013 crop using RADARSAT-2 data

32

Data set: RADARSAT-2, 2016

District Agency data (ton)

Estimated production (ton)

Difference percentage

(%)

An Phú 73,656 68,296 -7.3Chợ Mới 77,296 77,720 0.5Châu Phú 201,254 166,581 -17.2Châu Thành 166,054 148,199 -10.8Phú Tân 134,457 132,012 -1.8Tịnh Biên 89,584 111,364 24.3Châu Đốc 37,890 32,798 -13.4Long Xuyên 29,503 16,456 -44.2Thoại Sơn 233,292 202,704 -13.1Tri Tôn 229,200 204,518 -10.8Tân Châu 54,994 53,099 -3.4Total 1,325,946 1,213,746 -8.5

R² = 0.97

0

50,000

100,000

150,000

200,000

250,000

0 50,000 100,000 150,000 200,000 250,000

Estim

ated

pro

duct

ion

(ton)

Agency data (ton)

A distribution map of estimated rice yield of An Giang in SA 2016 crop using RADARSAT-2 data

Data set: ALOS-2, 2015

33

ALOS-2 data:- Band: L- Polarisation: HH&HV- Resolution: 50 m (WS) & 12.5 m (Fine)

SA 2015 crop (using 4-date ALOS-2 HH image, 10/04, 22/05, 03/07 & 14/08/2015)

Data set: Sentinel-1, 2015

34

WS 2015 crop (using 4-date S-1 image,17/12/2014, 10/01, 27/02 & 04/04/2015)

Overall acc.: 93%Kappa: 0.97

Sentinel-1 data:- Band: C- Polarisation: VV&VH- Resolution: 20 m (SW)

Data set: Sentinel-1, 2016

35

SA 2016 crop (using S-1 images)

R² = 0.9583

0

10,000

20,000

30,000

40,000

50,000

0 10,000 20,000 30,000 40,000 50,000

Estim

ated

are

a (h

a)

Agency data (ha)

District Agency data (ha)

Estimated area (ha)

Difference percentage (%)

An Phu 13,640 10,208 -25.2Cho Moi 13,304 11,351 -14.7Chau Phu 34,940 32,294 -7.6Chau Thanh 28,630 25,465 -11.1Phu Tan 22,151 23,329 5.3Tinh Bien 16,288 22,137 35.9Chau Doc 6,315 6,834 8.2Long Xuyen 4,518 3,819 -15.5Thoai Son 38,882 35,387 -9.0Tri Ton 42,210 41,661 -1.3Tan Chau 9,321 7,937 -14.9Total 230,199 224,774 -2.4

Data set: Sentinel-1, 2016

36

SA 2016 crop (using S-1 images) SA 2016 crop (using R-2 images)

Data set: Sentinel-1, 2015-2016 at regional scale

Reduced area in 2016 caused by shortage of water and saline water intrusion37

Map of WS Rice 2015 Map of WS Rice 2016

Data set: Sentinel-1, 2015-2016 at regional scale

38

Year WS Rice area (1000 ha)

1995 1035.71996 1152.21997 1254.01998 1349.01999 1448.52000 1520.62001 1537.62002 1513.72003 1498.92004 1467.12005 1478.72006 1500.32007 1506.52008 1526.52009 1548.82010 1564.62011 1567.52012 1580.22013 1564.42014 1562.72015 1562.32016 1383.3

0

200

400

600

800

1000

1200

1400

1600

1800

1990 1995 2000 2005 2010 2015 2020

Ric

e ar

ea o

f Mek

ong

Del

ta (1

000

ha)

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Extend the target area and increase the observation frequency; Validation activities for the rice crop estimation; Number of fields: 100 rice fields and 30 non-rice points for each of

the 3 regions• Region 1: An Giang; Kien Giang; Can Tho• Region 2: Dong Thap; Long An; Tien Giang• Region 3: Soc Trang; Tra Vinh, Vinh Long

Frequency: beginning, middle and end of season (3 times per rice season)

Capacity building activities for end user.

Discussion

39

40

VNREDSat-1 LOTUSAT-12013 2019