Measurement and quantification of the ecosystem services provided by an ecosystem form the basis of any conservation initiative. In a case of forest conservation projects, the significance of quantified values is even higher as it indicates the present condition, current trends (of deterioration or improvement of the natural resource) and the impact of implementation of conservation projects. Use of SAR technology to measure multiple aspects of forest vegetation and biomass has successfully increased the time and cost effectiveness of forest mapping, management, and carbon estimation activities; but the technology has, largely, not been used in India.
To advance India’s ability to accurately measure carbon sequestered in forests using remote sensing data, Space Application Centre (SAC), Ahmedabad has agreed to partner with Forest-PLUS and Karnataka Forest Department (KFD) to research the application of Synthetic Aperture Radar (SAR) technology in the estimation of forest biomass in Shimoga, Karnataka.
SAC plans on developing models to use Synthetic Aperture Radar (SAR) technology for accurate measurement of vegetation biomass of the forests and monitoring changes in the vegetation due to natural as well as anthropogenic causes. The research under this program relates to the development of retrieval models for vegetation parameters, specific to teak forests of Shimoga region, based on polarimetric and polarimetric interferometric (PollnSAR) SAR techniques. The specific retrieval models will be based on the capability of SAR’s polarimetric and interferometric mode to provide a dynamic range of vegetation growth variables which include tree structure, height, age, vegetation change, etc. The backscatter of C- and L- band also significantly correlate with density, biomass, and volume due to its ability to penetrate the crown.
Under this project, SAC has proposed to develop a Vector Radiative Transfer (VRT) model based approach to characterize scattering from teak vegetation and estimation of vegetation parameters such as above-ground woody biomass using hybrid and full polarimetric SAR data. They will also develop advanced models based on polarimetric interferometric (PollnSAR) tomography and dual-frequency SAR based models for retrieval of a teak biomass of higher ranges using L-band SAR data from ALOS-PALSAR-2, which is likely to be available during the project time frame (2014-2017).
SAC will acquire the following data for this study:
|Mission||Product Type||Incident Angle||Imaging Mode||Acquisitions||Total no. of Scenes|
|RISAT-1 C Band||Level-1 (SLC)||30º-35º||FRS (Linear/Hybrid)||Four times a year||16 scenes|
|RADARSAT-2 C Band||SLC Data||30º-35º||Fine resolution-Stripmap (Polarimetric)||Corresponding to RISAT data (for 1 year)||04 scenes|
|ALOS 2 PALSAR-2 Data (L-Band)||SLC Data||30º-35º||Fine resolution- (Polarimetric/ InSAR)||Corresponding to RISAT data (for 2 years)||16 scenes|
The study will be supported by synchronous ground truth surveys and measurements. During the pre-survey, detailed study of the area will be carried out using topographic maps, SRTM and ASTER derived DEM at 30/90 postings, soil and land use data, forest survey data and other ancillary data pertaining to the study area.
To summarize, SAC will be responsible for:
- Preparation of detailed work plan and literature review
- Preparation of plan for SAR data acquisition
- Data preparation and identifying gap areas in consultation with KFD
- Ground truth data collection, with support from KFD
- Initial data analysis and sharing knowledge with KFD
- Development of algorithm for vegetation characterization
- Biomass estimation modeling from polarimetric SAR and PollnSAR, with KFD
- Initial report generation
- Validation of technique, testing under controlled experiments in consultation with KFD
- Final report generation
KFD has agreed to support this study with the following:
- Manpower support for ground truthing
- Logistics and transport in the study area
- Relevant permissions for the study
- Sharing of scientific knowledge of the study area
The total financial value this project, including the cost of data acquisition, comes to around USD 50,000. This project will be spread over a period of three years, from 2014 to 2017. The study area in Shimoga coincides with the REDD+ project being developed in the Forest-PLUS pilot site.
The main outputs of the study will be:
- Biomass map of the area
- Methodology for forest vegetation characterization based on type, canopy structure and density using polarimetric SAR data.
- Robust models and methodology for estimation of Above Ground Biomass of plantations (with special reference to Teak, a major commercial plantation)