Methodology implementation and validation of TanDEM-X reference mapping was performed together with SarVision in Kalimantan, Indonesia. The chosen study site is located in a peat swamp forest which is characterized by drainage from the Mega Rice project which has led to increased fire vulnerability. Emissions from peat swamp forests equal about one quarter of the overall emissions from deforestation and degradation.
The pilot study shows that the TanDEM-X data is very useful to produce accurate land cover mapping, compliant with the 6 land cover categories mandatory for REDD+ MRV as specified by IPCC, and proved to be as accurate as conventional optical mapping results. Beyond basic classes it provides information on canopy cover and forest structure both related to forest biomass. Validation of quantitative forest characteristics with LIDAR measurements showed a good agreement with forest height and canopy cover.
Ghana was chosen as a second pilot case performed within the framework of public private partnership between GIZ1 and Astrium GEO. The goal of the pilot is to test the applicability of methods for the national REDD+ MRV development process including capacity building of relevant institutions involved in later MRV execution.
Forest destruction in Ghana is largely a process of progressive degradation driven by a mix of forces from within and particularly from outside the forest sector. Therefore, the emphasis was laid on the forest change assessment to demonstrate the potential for forest degradation mapping with TerraSAR-X.
Test sites have been distributed in the different eco-zones of Ghana, from the tropical moist South to the semi-arid North.
TerraSAR-X based change detection results confirmed a high level of forest changes in the main forest zone of Ghana. The found cases of deforestation and degradation are representative in terms of drivers such as legal and illegal gold mining, palm oil production and selective logging within forest reserves. The pilot proved that small scale scattered changes can also be detected in TerraSAR-X StripMap mode (3 m) but most reliably in very high resolution SpotLight mode with 1m resolution. Detected changes were validated during a field trip with Ghanaian trainees including staff from the forestry commission.
This pilot stands to contribute to the conservation of Bornean orangutans, the endangered apes that live only in Asia, by providing current information on the status of their forest habitats. By mapping and monitoring tropical forests using remote sensing data from the TanDEM-X mission, it can assess the status of tropical forests and detect forest degradation and loss. Using space-borne SAR data allows accessing remote areas within Borneo’s swamp forests in a timely manner and the assessment of the status of forests over large areas after, for example, fire events. This project will also strengthen local capacity: field work will be performed in collaboration with BOS-Mawas staff and local field assistants so the project will contribute to the training and transfer of field knowledge for Indonesians.
Given the level of forest degradation in Ghana in combination with the complexity of land use patterns and the dynamic nature of drivers of deforestation, it is proposed to use very high resolution imagery from TanDEM-X for reference mapping and TerraSAR-X for the subsequent monitoring of deforestation and forest degradation.
The proposed resolution offers better identification of features, change boundaries, drivers of change, and maps areas of forest degradation more accurately, than would be achieved with high resolution imagery such as Landsat.
The image to image change detection approach using TanDEM-X global archive as reference gives information on forest degradation at an early stage and therefore allows mitigation actions. Training on the job and verification of methodology was performed by Ghanaian users and led to recommendations of technology to the forestry commission of Ghana for REDD+ MRV implementation. Further validation and detailed cost benefit analysis will be performed in REDD pilot sites.