Wetland Spectro-Temporal Unmixing Using Multitemporal Multispectral Satellite Images

Download
2022-2-03
Özer, Erdem
Wetlands constitute one of the wealthiest and most productive ecosystems on earth. These areas are sophisticated aquatic habitats serving not only the locals but also the whole Earth system on a broad range. Following tropical forests, they have the highest biological diversity. These ecosystems are viable nourishment, reproduction, and sheltering environments for a whole range of living beings and are therefore accepted as natural wealth museums of the world. Monitoring such valuable areas and obtaining crucial information from them, in this regard, has been the primary motivation of the studies performed during the preparation of this thesis. When the sizes, geographic distribution, and total coverage of wetlands across the earth are taken into account, remote sensing shines out as the most economically and technically feasible method to realize the goals related to the mentioned motivation. Concerning the utilization of medium resolution satellite images as the input, the pixel-level approach falls short of understanding the wetland dynamics since vast amounts of pixels in such areas have mixed content. In this study, the soft classification of wetlands is aimed in order to determine all ground characteristics and their exact proportions. The path to achieving this goal passes through conducting an investigation within correct boundaries. Hence, detection of the wetland extent prior to sub-pixel analysis is addressed as a critical pre-processing step for realizing the subject motivation. The extent determination part includes calculating Tasseled Cap Water Index (TCWI) values on time series and modeling variations throughout the year by fitting a double-sided sigmoid function. This information is coupled with Digital Terrain Model (DTM) thresholding to extract the final extent. The sub-pixel analysis covers adopting a systematic approach using a three-element (soil, vegetation, water) scheme for establishing wetland ontology and implementing supervised spectral unmixing enhanced by the band and endmember optimizations. Balıkdamı, one of the most impressive wetlands of Turkey, is chosen as the test area. Open access optical satellite data, acquired by Sentinel-2 Multispectral Instrument (MSI), are utilized as the primary input. Since the abundance values of land cover classes in each Sentinel-2 pixel are estimated, reference abundance data with a 10 m grid interval are generated using four-band aerial images having a 30 cm ground sampling distance (GSD) for the verification stage. A new metric entitled "Abundance Confusion Matrix (ACOMA)" is introduced for the comparison and detailed assessment of reference and estimated fractional land cover. Experimental results demonstrate that the extent determination is addressed with a sensitivity of 93.55% and a precision of 99.21%. Moreover, abundance values of land cover classes are determined with overall accuracies of 66.17% and 66.27% for the monotemporal and multitemporal cases, respectively. In addition to a 2% overall accuracy increase compared to the hard classification, the detectability of sparse land cover classes is demonstrated that are vanished while using pixel-based approaches. Furthermore, gradients are able to be observed, particularly at watersides. As a result, the proposed method proves to be a valuable tool for the detailed monitoring of wetlands.

Suggestions

Türkiye Batı Ege Bölgesi’nde Sosyal ve Çevresel Değişime Karşı Hasar Görebilirlik Değerlendirmesi
Kozaman, Senem (Middle East Technical University, Faculty of Architecture, 2017-6-15)
Doğal değerlerin yoğun olduğu alanlar; bu değerlerin sürdürülebilirliği için koruma politikalarına konu olurken, diğer taraftan çevresel kaynakların çekiciliği nedeniyle artan nüfusun ve gereksinimlerinin yaratmış olduğu antropojenik baskı ve değişime maruz kalmaktadır. Özellikle kaynaklarıyla birçok ekosistem hizmeti sağlayan kıyı alanlarında küresel ölçekte son yüzyıldır çevresel değişimler yoğunluk göstermektedir. Sürdürülebilirliği kısıtlayan daimi tüketim eğilimi, çevresel bozulmalara ve kirliliğe nede...
Mediterranean shrub classification using multitemporal multi-spectral satellite images
Listiani, Indira Aprilia; Leloğlu, Uğur Murat; Zeydanlı, Uğur Siyami; Department of Geodetic and Geographical Information Technologies (2021-2-12)
Shrublands, which have a crucial role in retaining the ecological balance, constitute an important part of the Mediterranean ecosystems. However, their composition, distribution and dynamics are not well understood. It is necessary to know the distribution of the alliances at regional scale in order to construct models that explain their dynamics. Such models will help researchers to evaluate their role in ecosystems and predict their responses to climate change. Necessary alliance distribution maps can onl...
Development of an online support tool for biodiversity training of forest engineers in Turkey
Önal, Özgür Ş; Özden, M. Yaşar; Department of Computer Education and Instructional Technology (2014)
Biodiversity is one of the most important elements of the sustainable forestry practices. However, in Turkey biodiversity is not properly included in the forestry training curriculum and in professional training. There is a gap in the education of forest engineering about biodiversity. This study aims to fill this gap by developing an online support tool targeting dissemination of the biodiversity training with lower cost and time. The primary aim of this study is to explore the potential of web based tool ...
Near-Optimal Design of Scalable Energy Harvester for Underwater Pipeline Monitoring Applications With Consideration of Impact to Pipeline Performance
Qureshi, Fassahat Ullah; Muhtaroglu, Ali; Tuncay, Kağan (2017-04-01)
Underwater pipelines are often necessary to transport valuable resources between patches of land, and are expected to have increased utilization across the globe with the steep population increase on one hand, and unbalanced depletion of resources on the other. It is desirable to automate monitoring of various performance parameters associated with the pipelines through wireless sensor networks to ensure longevity of use and reduced running costs. However, such pipelines are not easily accessible, and are s...
Agricultural reuse of water and nutrients from wastewater treatment in İzmir Region
Sarıkaya, Ebru; Demirer, Göksel Niyazi; Department of Environmental Engineering (2012)
Rapid urbanization and population growth have represented a great challenge to water resources management, since wastewater generated in urban areas forms a non-conventional source, wastewater reuse is being recognized as a sustainable water management approach. This study focuses on with the potential and practibility of implementing wastewater reuse techniques in İzmir region, especially with the aim to use treated wastewater and nutrient for agriculture. To this end, qualititative and quantitative agricu...
Citation Formats
E. Özer, “Wetland Spectro-Temporal Unmixing Using Multitemporal Multispectral Satellite Images,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.