Jo rg Haarpaintner Norut, N-9294 Tromsø, Norway

Transcription

1 Validation of SAR-based forest land cover and forest change maps and detectability of slash-and-burn activities in the Kwamouth region, Mai-Ndombe District, DRC. Jo rg Haarpaintner Norut, N-9294 Tromsø, Norway

2 SAR for REDD+ ESA DUE INNOVATOR III Project ( ) Contractor: Norut Northern Research Institute, Tromsø, Norway User: Observatoir Satellitale des Forêts d Afrique Centrale (OSFAC) Kinshasa, DR Congo Contact: Dr Jo rg Haarpaintner joergh@norut.no Contact: Dr Landing Mane lmane@osfac.net Objective 1) Providing Synthetic Aperture Radar processing capabilities to REDD countries for their Monitoring, Reporting and Verification. 2) Demonstrating SAR image mosaicking, SAR-based forest and forest change mapping in the Mai-Ndombe district in DRC VALIDATION with FIELD DATA REDD+ = Reducing Emissions from Deforestation and Forest Degradation + Reforestation, Sustainable Forest Management & Conservation

3 Products to be validated Forest Land Cover Maps Forest/Non-Forest Maps Forest Change Maps LEGEND Forest Inundated Forest Savannah Dry Grassland Wet Grassland River Swamp Water No data Outside of AOI LEGEND Forest Non-Forest Water No data Outside of AOI LEGEND Forest Non-Forest Water Forest Loss Forest Gain No data Outside of AOI Color Based on dual-polarized PALSAR ( ) ALOS-2 PALSAR-2 ( ) Sentinel-1A ( )

4 Forest Land Cover and Forest/Non-Forest Validation with 2015 SPOT-5 and 2016 Pe iades imagery 924 manual interpreted pixel samples on a 4.2 km 2 / 2.1 km 2 grid FSG = Forest-Savannah-Grassland validation: C-band: forest inundated forest savannah dry/wet grassland river swamp L-band: forest inundated forest savannah dry/wet grassland river swamp Sensor Band Year FSG FNF ALOS PALSAR L ALOS-2 PALSAR-2 L Sentinel-1 C Accuracy Kappa Accuracy Kappa Accuracy Kappa

5 Study Site: Mai-Ndombe District in DRC ( km 2 ) Fieldwork Site: Kwamouth region Sentinel-1A Mosaic (data since April 2015) RGB = VV,VH,NDI SPOT5/Take5 scene from 25 Jun ( CNES) Pleiades images from 19/21 Nov ( CNES/AirbusDS) Fieldwork area: Kwamouth region Kwamouth 2016

6 Fieldwork Site: Kwamouth region Sentinel-1A Mosaic (data since April 2015) RGB = VV,VH,NDI Pleiades image from 19 Nov sampled every 2.1 km in forestsavannah-grassland ( CNES/AirbusDS) Transect from Masia- Mbio to Kwamouth Collection of: a. GPS track b. Ground photos c. GPS positions of forest/non-forest transitions (flags), d. 11 aerial image mosaics with a small RC quadrocopter (Fxx) e. Tree height & tree count measurements

7 Ground photos and GPS positions

8 138 GPS positions of forest border along the track Do they fall in a border pixel of the FNF products (0) or at which pixel distance (at 30m-resolution)? Sensor Year 0 <42m 30m Pixel Distance of GPS Forest Border Position to next border pixel in FNF products 1 <84m 2 <127m 3 <170m 4 <212m 5 <255m >5 >255m Mean Sentinel Sentinel-1/ALOS ALOS-2 PALSAR Envisat ASAR -AP ALOS PALSAR Envisat ASAR -WS

9 11 Aerial Mosaics from a RC Quadrocopter DJI Phantom-3pro

10 Forest Change (PALSAR to PALSAR-2) based on a 3dB decrease in HV backscatter, red areas represent forest loss > 0.5 ha within a 9 ha area LEGEND Color Pixel Value Forest 10 Non-Forest 30 Water 60 Forest Loss 210 Forest Gain 220 No data 250 Outside of AOI 255

11 Field Validation LEGEND Forest Inundated Forest Savannah Dry Grassland Wet Grassland River Swamp Water Forest Loss (ALOS-GFC) Forest Loss (GFC) Forest Loss (ALOS) No data Outside of AOI Google Earth image early 2016 Aerial image from 10 September 2016 showing forest loss and 2 burned areas

12 Aerial Mosaic (2016) ALOS ALOS-2 ( ) Sentinel-1A ( ) Landsat 2014 (GFC) FNF (ALOS) FNF (ALOS-2) FNF (S1A)

13 5-year forest loss Aerial Mosaic ALOS ALOS-2 ( ) Forest Loss Landsat (GFC) GFC GFC (Hansen et al. 2013) 5-year forest loss

14 Forest Change (S1A and PALSAR-2) based on a 3dB decrease on either HV (ALOS-2) or VH (S1A), red areas represent forest loss > 0.5 ha within a 9 ha area LEGEND Color Pixel Value Forest 10 Non-Forest 30 Water 60 Forest Loss 210 Forest Gain 220 No data 250 Outside of AOI 255

15 5-year forest loss Aerial Mosaic ALOS ALOS-2 ( ) Forest Loss GFC ALOS ALOS Forest Loss year forest loss

16 Aerial Mosaic S1A (2015) S1A (2016) Forest Loss GFC ALOS-2 (2015) ALOS-2 (2016) Forest Loss year forest loss

17 Final burning 5-year forest loss Aerial Mosaic S1A (16 Jun 2016) S1A (20 Sep 2016) Forest Loss GFC ALOS-2 (16 Jun 2016) ALOS-2 (22 Sep 2016) Forest Loss year forest loss

18 Comparison Forest Change (S1A / PALSAR-2) with Pléiade imagery Forest loss based on a 3dB decrease on either HV (ALOS-2) or VH (S1A) between 2015 and 2016 averaged mosaics

19 CONCLUSION Field mission was a success in regard to validation. Photos and visual observations confirmed well the forestsavannah-(wet/dry)grassland classification of ALOS PALSAR as well as deforestation locations GPS position of forest border provide an alternative validation method for FNF maps showing best performance of Sentinel-1. Aerial imagery from small drones and VHR satellite data confirm the detectability by SAR of forest loss (L) and burn-scares (C). Combination of C-band and L-band SAR data and dense times series provide a better time specification of the activities on a multi-year, yearly base for deforestation and yearly/monthly base for slash-and-burn activities. Full exploitation of field data: tree height/count for biomass.

20 Thank you for your attention. Acknowledgements André Mazinga (OSFAC), F. Kayembe (MECNT/DIAF) Satellite Data has been provided by ESA (Sentinel Science Hub, cat-1 proposal nr 27689, GSC-DA grant from ESA and JAXA during EU FP7 Project ReCover), JAXA ALOS-2 RA4 proposal SPOT5 data CNES-Spot5Take Ple iades data CNES 2016 and Airbus DS 2016, all rights reserved. Landsat results from GFC (Hansen et al. 2013) GoogleEarth Funding has been provided by ESA DUE Innovator III project SAR for REDD (Contract Nr /15/I-NB).