University of Twente Student Theses
Assessment of the effect of UAV and pleiades spatial resolution and band combination on biomass estimation in Haagse Bos, The Netherlands.
Chundu, Misheck Lesa (2021) Assessment of the effect of UAV and pleiades spatial resolution and band combination on biomass estimation in Haagse Bos, The Netherlands.
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| Abstract: | Forests play an important role in mitigating climate change because they act as both a carbon sink and a carbon source. Climate change is putting increasing pressure on the forest ecosystems of European forests. Most of the carbon is stored in the forest Aboveground biomass (AGB), which is used in carbon inventory and mitigation and as an essential climate variable and a critical input to the United Nations' Reducing Emissions from Deforestation and Degradation-plus (REDD+) program. 50% of dry forest AGB represents carbon; therefore, accurate estimation of forest AGB is a vital step in monitoring carbon stocks and changes in the forest. The effective and accurate estimation of forest AGB is one of the most challenging tasks; finding a reliable and accurate method to estimate forest AGB is critical. Remote sensing is well-placed to provide accurate, realistic, and cost-effective AGB estimates with large spatial and multi-temporal observation. Unmanned Aerial Vehicle (UAV) is less expensive, provides reliable data quality, and multitemporal capturing of forest parameters at a very high spatial resolution. The satellite data (Pleiades) is readily available with huge datasets archived, large spatial coverage, provide consistent spatial data, repetitive with high revisit time (daily), as well as a relatively cost-effective way of biomass estimation at a large scale. This research aimed to extract the crown projection area (CPA) of individual trees in a coniferous forest through Object-Based Image Analysis (OBIA) of UAV and Pleiades satellite images with different spatial resolutions (10 cm, 20 cm, 30 cm, 40 cm, and 50 cm) and band combinations (1,1,1,4 –UAV_MS, 1,4,1,0 –UAV_RGB and 1,1,1,4 – Pleiades); investigate if variations in the extracted CPA leads to significant differences in AGB estimates. The fieldwork was carried out between August 2020, and October 2020. Pleiades satellite image was acquired on August 22, 2019. The UAV_MS and UAV_RGB images were acquired in August 2020 and September 2020 using the Phantom 4 drone. The t-test results showed that means of the UAV_MS and UAV_RGB modelled AGB (AGB-est) per tree at 10 cm spatial resolution were not significantly different from means of the field estimated AGB (AGB-f) per tree. At 20 cm and 30 cm spatial resolutions, the means of the field estimated AGB-f per tree were also not significantly different from the means of the AGB-est per tree estimated with UAV_MS, but significantly different from the means of AGB-est per tree estimated with UAV_RGB. The means of field estimated AGB-f per tree were significantly different from the means of AGB-est per tree from both UAV_MS and UAV_RGB at 40 cm and 50 cm resolutions as well as Pleiades at 50 cm spatial resolution. The t-test results for AGB per plot (500 m2), showed that there were no significant differences between the means of the AGB-f per plot and the means of AGB-est per plot estimated from UAV_RGB and UAV_MS at 10 cm, 20 cm, 30 cm, 40 cm, and 50 cm as well as Pleiades at 50 cm spatial resolution. It was concluded that the AGB per tree could be accurately estimated at 10 cm spatial resolution with UAV_MS and UAV_RGB, as well as at 20 cm and 30 cm spatial resolution with UAV_MS. The AGB per plot could be estimated with reasonable accuracy using UAV_RGB and UAV_MS at 10 cm, 20 cm, 30 cm, 40 cm, and 50 cm spatial resolutions as well as Pleiades at 50 cm spatial resolution. |
| Item Type: | Essay (Master) |
| Faculty: | ITC: Faculty of Geo-information Science and Earth Observation |
| Programme: | Geoinformation Science and Earth Observation MSc (75014) |
| Link to this item: | https://purl.utwente.nl/essays/88781 |
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