Analisis Sebaran Koheren InSAR pada Musim Basah dan Musim Kering di Wilayah Surabaya Menggunakan Data Sentinel-1

Rahmah, Siti fadlilah rahmah (2026) Analisis Sebaran Koheren InSAR pada Musim Basah dan Musim Kering di Wilayah Surabaya Menggunakan Data Sentinel-1. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penelitian ini direncanakan untuk menganalisis pola koherensi dan amplitudo citra Sentinel-1 InSAR pada musim basah dan musim kering di wilayah Surabaya sebagai dasar penyusunan metode pemantauan penurunan muka tanah di kawasan perkotaan pesisir. Fokus kajian adalah menganalisis perubahan nilai koherensi dan amplitudo pada berbagai jenis tutupan lahan, yaitu permukiman, sawah, dan mangrove, antar musim, serta mengkaji keterkaitan nilai tersebut dengan kondisi permukaan berdasarkan data ground truth lapangan. Data yang digunakan berupa pasangan citra Single Look Complex (SLC) Sentinel-1 Interferometric Wide Swath (IW) yang diolah menggunakan perangkat lunak SNAP melalui tahapan TOPSAR Split, koregistrasi, pembentukan interferogram, perhitungan koherensi dan amplitudo, multilooking, phase unwrapping, serta terrain correction berbasis DEM. Selain itu, dilakukan pengambilan data ground truth berupa titik GPS dan foto geotagged untuk memvalidasi sebaran nilai koherensi dan amplitudo pada setiap jenis tutupan lahan. Hasil penelitian menunjukkan bahwa nilai koherensi pada musim kering secara umum lebih tinggi dibandingkan musim basah, dengan estimasi rata-rata koherensi pada musim kering bulan Juni 2024 sebesar 0,55–0,65, sedangkan pada musim basah Januari 2024 berada pada kisaran 0,35–0,40. Validasi lapangan terhadap 25 titik yang tersebar pada lima kelas koherensi menunjukkan tingkat kesesuaian sebesar 100%, yang mengonfirmasi bahwa peta koherensi Sentinel-1 mampu merepresentasikan kondisi tutupan lahan aktual secara akurat. Kawasan terbangun permanen secara konsisten menghasilkan nilai koherensi tertinggi (0,8–1,0), sedangkan badan air menghasilkan nilai koherensi terendah yang mendekati nol. Sebaliknya, nilai amplitudo terbukti jauh lebih stabil antarmusim, dengan selisih rata-rata hanya sekitar 0,4–0,6 dB, yang menunjukkan bahwa amplitudo lebih dipengaruhi oleh karakteristik struktural permukaan yang bersifat permanen dibandingkan oleh perubahan musiman. Penelitian ini juga menemukan anomali pada tahun 2025, ketika koherensi pada musim basah sedikit lebih tinggi daripada musim kering, yang diduga disebabkan oleh intensitas curah hujan yang tidak tipikal serta perbedaan karakteristik teknis pasangan citra. Melalui penelitian ini dihasilkan peta sebaran koherensi dan amplitudo pada musim basah dan musim kering, nilai ambang (threshold) koherensi yang sesuai untuk setiap jenis tutupan lahan di Surabaya, serta rekomendasi parameter baseline dan kualitas data yang layak digunakan sebagai masukan dalam analisis PS-InSAR pada tahap penelitian berikutnya. Hasil tersebut diharapkan dapat mendukung pengembangan metode pemantauan penurunan muka tanah di wilayah Surabaya secara lebih efektif dan berkelanjutan.
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This study analyzed the coherence and amplitude patterns of Sentinel-1 InSAR imagery during the wet and dry seasons in Surabaya as a basis for developing a land subsidence monitoring method for urban coastal areas. The main objective was to investigate how coherence and amplitude values over different land cover classes, including settlements, rice fields, and mangroves, vary between seasons and how these values relate to surface conditions observed through field-based ground truth data. The dataset consisted of Single Look Complex (SLC) Sentinel-1 Interferometric Wide Swath (IW) image pairs processed using SNAP software through TOPSAR Split, coregistration, interferogram generation, coherence and amplitude calculation, multilooking, phase unwrapping, and DEM-based terrain correction. In addition, ground truth data in the form of GPS points and geotagged photographs were collected to validate the spatial distribution of coherence and amplitude values across each land cover class. The results indicate that coherence values during the dry season were generally higher than those during the wet season, with average coherence values of 0.55–0.65 in June 2024, compared with 0.35–0.40 in January 2024. Field validation at 25 locations distributed across five coherence classes achieved 100% agreement, confirming that the Sentinel-1 coherence map accurately represents actual land cover conditions. Permanent built-up areas consistently exhibited the highest coherence values (0.8–1.0), whereas water bodies showed the lowest coherence values, approaching zero. In contrast, amplitude values remained considerably more stable between seasons, with an average difference of only 0.4–0.6 dB, indicating that amplitude is influenced more strongly by the permanent structural characteristics of the surface than by seasonal variations. An anomaly was also observed in 2025, when wet-season coherence values were slightly higher than those of the dry season, which is presumed to have resulted from atypical rainfall intensity and differences in the technical characteristics of the image pairs. This study produced coherence and amplitude distribution maps for both wet and dry seasons, established appropriate coherence thresholds for each land cover type in Surabaya, and provided recommendations regarding baseline parameters and data quality suitable for subsequent PS-InSAR analysis. These findings are expected to support the development of a more effective and sustainable land subsidence monitoring method for the Surabaya region.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Kata kunci: Koherensi InSAR; amplitudo Sentinel‑1; musim basah dan kering; tutupan lahan Surabaya; ground truth; SNAP; PS‑InSAR; penurunan muka tanah.
Subjects:	G Geography. Anthropology. Recreation > G Geography (General) G Geography. Anthropology. Recreation > G Geography (General) > G70.217 Geospatial data T Technology > TA Engineering (General). Civil engineering (General) > TA590 Topographical surveying
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geomatics Engineering > 29202-(S1) Undergraduate Thesis
Depositing User:	Siti Fadlilah Rahmah
Date Deposited:	23 Jul 2026 03:00
Last Modified:	23 Jul 2026 03:00
URI:	http://repository.its.ac.id/id/eprint/136357

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