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

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1 International Meeting on Land Use and Emissions in South/Southeast Asia Ho Chi Minh City, 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-Toan Centre d'etudes Spatiales de la BIOsphère (CESBIO), France Viet Pham-Bach, Mai Thy Pham-Thi GIS and Remote Sensing Research Center (GIRS) HCMIRG VAST

2 Contents 1. Introduction 2. Land use change in the Mekong Delta, Vietnam 3. Rice crop monitoring 4. Discussion 2

590 M (~1/5) MD accounts for more than half (25.7 / 45.

3 INTRODUCTION Source: Parry, M.L. et al., 2007 Mekong Delta (Source: GSO, 2015): Area: 40,576 Km 2 (1/8) Population: 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.

LAND USE CHANGE - Introduction State-level project (2013-2016): Utilisation of satellite imagery VNREDSat-1 and equivalent for monitoring agricultural

4 LAND USE CHANGE - Introduction State-level project ( ): 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. 4 VNREDSat-1 (7 scenes) and Landsat data used

5 LAND USE CHANGE - Introduction Landsat 5, 21/2/1996 Landsat 7, 20/01/ Landsat 8, 27/2/2014

089 samples, 70% for training data; 30% for

6 LAND USE CHANGE - Introduction Field work: collecting samples, 70% for training data; 30% for accuracy assessment. 6 1 st field trip (6-16/1/2014) 2 nd field trip (11-17/4/2014)

7 LAND USE CHANGE Results from Landsat Overall Acc.: 80 % Kappa: 0,

8 LAND USE CHANGE - Results from Landsat

9 LAND USE CHANGE - Results from Landsat Agricultural land use was changed in the period of ; Rice and aquaculture land fast increased during the period of ; 9

10 LAND USE CHANGE Results from VNREDSat-1 LU change Rice in Thoai Son, An Giang ( ) LU change Fruit tree in Cai Be, Tien Giang ( ) 10

11 LAND USE CHANGE - Results from VNREDSat-1 LU change Forest in Tram Chim, Dong thap ( ) LU change Aquaculture in Vinh Chau, Soc Trang ( ) 11

12 12 Wetland map of Lower Mekong basin (2015)

RICE CROP MONITORING - Introduction Previous projects 1.

algorithm Yield estimation model: Statistical model. 2.

Single-date mapping algorithm Yield estimation model: Statistical model. 3.

13 RICE CROP MONITORING - Introduction Previous projects 1. Rice & Mangrove monitoring in Southern Vietnam - RICEMAN TerraSAR-X & ENVISAT-ASAR data, 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, Rice mapping: Single-date mapping algorithm Yield estimation model: Statistical model. 3. Utilisation of SAR data for rice crop monitoring ERS2-SAR data, Rice mapping: Temporal change measurement Yield estimation model: Agro-meteorological model (AMM). 4. Other projects in the Mekong and Red River Delta Ongoing projects 1. SAFE/APRSAF ( ) &Asia-RiCE 2. GeoRice ( ) Data used: COSMO-SkyMed, RADARSAT-2, ALOS-2, Sentinel-1. 13

Introduction Rice cropping system Rice season Single rice crop Traditional

SA AW (rain-fed) WS SA (irrigated) Triple rice crop WS SA - AW Main rice-based

growing stages Rice crop Planting Harvesting English name Local name Winter

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

14 Introduction Rice cropping system Rice season Single rice crop Traditional rice (rain-fed) Sowing-transplanting period Vegetative stage Double rice crop SA AW (rain-fed) WS SA (irrigated) Triple rice crop WS SA - AW Main rice-based cropping systems in the MD Reproductive stage Ripening stage Pictures of rice growing stages 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. 14 Main rice seasons in An Giang province, Mekong Delta

15 Introduction Objectives: To evaluate the use of SAR data in rice mapping, monitoring and yield estimation, towards an operational system for rice crop inventory in the Mekong Delta, Vietnam. 24/03/07 17/02/

coordinates: UL: 10 58'47.38"N, 104 44'39.51"E, UR:10 58'35.

16 Ongoing research works Asia-RiCE&SAFE, GEORice Technical Demonstrator Site Mekong Delta, VN An Giang province, Mekong Delta, Vietnam Geographic coordinates: UL: 10 58'47.38"N, '39.51"E, UR:10 58'35.84"N, '12.84"E LR: 10 05'24.65"N, '15.36"E, LL: 10 05'45.13"N, '23.41"E 16

Methods SAR data Ground-truth data σ o of sampling fields Classification method Thresholding 24/03/07 In situ rice yield Regression analysis Regression equation Classification maps

17 Methods SAR data Ground-truth data σ o of sampling fields Classification method Thresholding 24/03/07 In situ rice yield Regression analysis Regression equation Classification maps Asia-RiCE Target Agricultural Products Estimated rice yield distribution maps Accuracy assessment Reference data Ground data Estimated rice production (P5) Rice/Non-rice maps (P1) 17

Data set SAR data received: COSMO-SkyMed: Aug 2013 Feb 2014 RADARSAT-2: Aug 2013 Now Sentinel-1: Aug 2014 Now ALOS-2: Nov 2014 Now Rice crops monitored: 2013: AW; 2014-2016: WS, SA, AW.

18 Data set SAR data received: COSMO-SkyMed: Aug 2013 Feb 2014 RADARSAT-2: Aug 2013 Now Sentinel-1: Aug 2014 Now ALOS-2: Nov 2014 Now Rice crops monitored: 2013: AW; : WS, SA, AW. 18 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-1 6 October 2014

19 General parameters 19 Guidelines for ground data collection for rice monitoring experiments using radar data (Thuy Le Toan) Leaf parameters (optional) Panicle parameters Rice parameters Description Equipment Paddy variety Data set: CSK & RSAT-2, Ex.: IR Method of planting direct sowing/ transplanting Sowing date Transplanting date (if transplanting) Date of harvesting Yield (kg/m 2 ) date of direct sowing or number of days after sowing date of transplantation or the number of days after transplantation if the rice has been harvested if the rice have been harvested Seeding, transplanting, tillering, Plant phenological stage heading, flowering, ripening, ready to harvest Water layer height (cm) if fields are flooded stick Plant height (cm) above water layer tape Wet weight per m 2 (g) Dry weight per m 2 (g) Number of leaves per stem Leaf length (cm) Leaf width (cm) Moist and dry biomass of panicles per m 2 above water biomass (moist weight by m 2 ) cut all plants from defined areas (min 50 x 50 cm) objective is to measure the dry Oven dry (105 biomass per m 2 during 24 hours) Few samples for each sortie -Photo -Xerox copy of leaves

20 15.0 Data set: CSK, HH/VV (db) CSK_PP_ CSK_PP_ CSK_PP_ CSK_PP_ CSK_PP_ CSK_PP_ HH/VV (db) 20 TSX ( ) -5.0 CSK_PP_ CSK_PP_ CSK (2013) Days Ngày after sau sowing khi sạ TĐ2010_CM 4.0 ĐX2011_CM 2.0 ĐX2011_TL Số ngày sau sạ/cấy HH/VV (db) ASAR APP(2007) Days after sowing WS SA AW WS0 SA0 AW0

21 Data set: CSK, AW 2013 crop from CSK PP (20 Sep and 14 Oct 2013) Overall acc.: 89% Kappa: WS 2014 crop from CSK PP (11 Feb 2014)

22 Estimated area Agency data Percentage error Commune Name (ha) (ha) (%) An Bình 2,274 2, Bình Thành 2,313 2, Định Mỹ 3,178 2, Định Thành 2,613 2, Mỹ Phú Đông 2,676 2, Phú Thuận 1, Thoại Giang 2,203 2, Núi Sập Óc Eo Phú Hòa Vĩnh Khánh 2,500 2, Vĩnh Phú 3,069 3, Vĩnh Trạch 1,269 1, Vĩnh Chánh 2,357 1, Vọng Đông 2,601 2, Total 29,455 28, Data set: CSK, Agency data (ha) 3,500 3,000 2,500 2,000 1,500 1, 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 0 y = x R² = ,000 1,500 2,000 2,500 3,000 3,500 Estimated area (ha)

23 Data set: CSK, AW 2007 crop from ASAR APP AW 2010 crop from ASAR APP AW 2013 crop from CSK PP

Data set: CSK, 2013-2014 Y Ra = 6.66696 0.483956*Ra 1 0.

5 ton/ha Where: A distribution map of estimated rice yield in AW Y Ra

polarisation ratio of first date image, districts using three-date

CSK 04 Sep 2013 Ra 3 : polarisation ratio of third date image, r 2 :

24 Data set: CSK, Y Ra = *Ra *Ra *Ra 3 r 2 = 0.646, se y = 0.5 ton/ha Where: A distribution map of estimated rice yield in AW Y Ra : rice yield (ton/ha), 2013 crop at Chau Thanh and Thoai Son Ra 1 : polarisation ratio of first date image, districts using three-date polarisation ratios: Ra 2 : polarisation ratio of second date image, CSK 04 Sep 2013 Ra 3 : polarisation ratio of third date image, r 2 : the coefficient of determination, CSK 22 Oct 2013 se y : the standard error for the y estimate. CSK 07 Nov

25 Commune name 25 Estimated production (ton) Agency data (ton) Percentage error (%) Vinh Thanh 11,655 11, Vinh Nhuan 19,097 18, Vinh Loi 12,620 13, Hoa Binh Thanh 13,539 14, TT. An Chau 2,744 3, Binh Hoa 7,076 6, Vinh Binh 14,220 12, Vinh Hanh 14,653 15, Can Dang 12,688 12, An Hoa 3,048 2, Binh Thanh 14,028 13, Dinh My 19,492 17, Dinh Thanh 14,951 14, My Phu Dong 15,114 18, Phu Thuan 4,961 5, Thoai Giang 13,865 13, TT. Nui Sap 2,905 2, TT. Oc Eo 3,390 3, TT. Phu Hoa 1,436 1, Vinh Khanh 14,432 16, Vinh Phu 18,541 19, Vinh Trach 7,404 8, Vinh Chanh 11,538 12, Vong Dong 16,158 12, Total 269, , Estimated production (ton) Data set: CSK, y = x R² = Agency data (ton) Chau Thanh Thoai Son Accuracy assessment of estimated production for AW 2013 crop at Chau Thanh and Thoai Son district using three-date polarisation ratios (HH/VV) of CSK (04 Sep, 22 Oct, 07 Nov 2013) based on statistical data

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

27 Data set: RADARSAT-2, AW 2013 crop from RADARSAT-2 (29 Aug & 09 Nov 2013) AW 2013 crop from CSK PP (20 Sep & 14 Oct 2013) 27

28 Data set: RADARSAT-2, 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 Commune name Estimated area (ha) Agency data (ha) Percentage error (%) RADARSAT-2, Thoai Son District - AW2013 An Binh 2,422 2, Binh Thanh 2,316 2, Đinh My 3,274 2, Đinh Thanh 2,743 2, My Phu Đong 2,828 2, Phu Thuan Tay Phu 1,936 2, Thoai Giang 2,349 2, Nui Sap Oc Eo Phu Hoa Vinh Khanh 2,545 2, Vinh Phu 3,213 3, Vĩnh Trach 1,303 1, Vinh Chanh 1,530 1, Vong Đong 2,620 2, Vong The 2,383 2, Total 32,875 33, Agency data (ha) 3,500 3,000 2,500 2,000 1,500 1, y = x R² = ,000 1,500 2,000 2,500 3,000 3,500 Estimated area (ha)

Data set: RADARSAT-2, 2016 District Agency data (ha) Estimated area (ha) Difference percentage (%) An Phu 13,640 13,679 0.3 Cho Moi 13,304 14,784 11.1 Chau Phu 34,940 30,274-13.

29 Data set: RADARSAT-2, 2016 District Agency data (ha) Estimated area (ha) Difference percentage (%) An Phu 13,640 13, Cho Moi 13,304 14, Chau Phu 34,940 30, Chau Thanh 28,630 26, Phu Tan 22,151 23, Tinh Bien 16,288 21, Chau Doc 6,315 6, Long Xuyen 4,518 3, Thoai Son 38,882 37, Tri Ton 42,210 38, Tan Chau 9,321 9, Total 230, , ,000 40,000 R² = 0.97 Estimated area (ha) 30,000 20,000 10, SA 2016 crop from RADARSAT-2 (15 Apr, 09 May, 02 Jun, 26Jun, 20 Jul & 13 Aug) ,000 20,000 30,000 40,000 50,000 Agency data (ha)

Data set: RADARSAT-2, 2013-2014 A distribution map of estimated rice

three-date VH polarisation: RADARSAT-2 29 Aug 2013 RADARSAT-2 16 Oct

in WS 2014 crop at Chau Thanh and Thoai Son district using three-date

30 Data set: RADARSAT-2, 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

31 Data set: RADARSAT-2, A distribution map of estimated rice yield of An Giang in AW 2013 crop using RADARSAT-2 data

Data set: RADARSAT-2, 2016 250,000 R² = 0.

100,000 150,000 200,000 250,000 Agency data (ton) District Agency data (ton) Estimated production (ton) Difference percentage (%) 32 An Phú 73,656 68,296-7.

32 Data set: RADARSAT-2, ,000 R² = 0.97 A distribution map of estimated rice yield of An Giang in SA 2016 crop using RADARSAT-2 data Estimated production (ton) 200, , ,000 50, , , , , ,000 Agency data (ton) District Agency data (ton) Estimated production (ton) Difference percentage (%) 32 An Phú 73,656 68, Chợ Mới 77,296 77, Châu Phú 201, , Châu Thành 166, , Phú Tân 134, , Tịnh Biên 89, , Châu Đốc 37,890 32, Long Xuyên 29,503 16, Thoại Sơn 233, , Tri Tôn 229, , Tân Châu 54,994 53, Total 1,325,946 1,213,

33 Data set: ALOS-2, 2015 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) 33

34 Data set: Sentinel-1, 2015 Sentinel-1 data: - Band: C - Polarisation: VV&VH - Resolution: 20 m (SW) Overall acc.: 93% Kappa: 0.97 WS 2015 crop (using 4-date S-1 image, 17/12/2014, 10/01, 27/02 & 04/04/2015) 34

35 Data set: Sentinel-1, 2016 District Agency data (ha) Estimated area (ha) Difference percentage (%) An Phu 13,640 10, Cho Moi 13,304 11, Chau Phu 34,940 32, Chau Thanh 28,630 25, Phu Tan 22,151 23, Tinh Bien 16,288 22, Chau Doc 6,315 6, Long Xuyen 4,518 3, Thoai Son 38,882 35, Tri Ton 42,210 41, Tan Chau 9,321 7, Total 230, , ,000 40,000 R² = Estimated area (ha) 30,000 20,000 SA 2016 crop (using S-1 images) 10, ,000 20,000 30,000 40,000 50,000 Agency data (ha)

36 Data set: Sentinel-1, 2016 SA 2016 crop (using S-1 images) SA 2016 crop (using R-2 images) 36

37 Data set: Sentinel-1, at regional scale Map of WS Rice 2015 Map of WS Rice Reduced area in 2016 caused by shortage of water and saline water intrusion

38 Data set: Sentinel-1, at regional scale 38 Rice area of Mekong Delta (1000 ha) Year WS Rice area (1000 ha)

39 Discussion 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. 39

40 VNREDSat-1 LOTUSAT

Adaptability Zoning for Salty-Tolerant Rice Varieties in Soc Trang Prefecture by Using GIS and Remote Sensing

Journal of Geological Resource and Engineering 3 (2016) 142-150 doi:10.17265/2328-2193/2016.03.005 D DAVID PUBLISHING Adaptability Zoning for Salty-Tolerant Rice Varieties in Soc Trang Prefecture Tran