Analysing Peatland Subsidence in Pelalawan Regency, Riau Using DInSAR Method

Indonesia is known as a country that have the largest peatland in Southeast Asia. Peatland is often used in agricultural, plantation and settlement purposes. Before, peatland must be drained as one procedure of land clearing activity. However, an error during this process often comes and cause some problems such as drought, subsidence and even forest fire. A characteristic of peatland, irrewetable, making peatland is very hard to be wet after getting dry. This research is aiming to observe peatland subsidence in Pelalawan Regency, Riau using SAR data Sentinel 1-A. The method that we use is Differential Interferometry Synthetic Aperture Radar (DInSAR). Beside Sentinel 1-A, DEM STRTM is used to remove topographic effect. Temporal baseline in this research is about one year between two acquisition data. The first pair of data is acquired in June 2015 and June 2016. While the second pair of data is acquired in June 2016 and July 2017. By using two pass DInSAR method, the process will yield two images of Line of Sight (LOS) Displacement during each period. The first DInSAR (June 2015-June 2016) reveals that the highest subsidence that occur in peatland is about 109,113 mm and the highest uplift is about 108,089 mm. The second DInSAR (June 2016-July 2017) reveals that the highest peat subsidence is about 251,842 mm and the highest uplift is about 73,715 mm

Analisis Penurunan Permukaan Lahan Gambut di Kabupaten Pelalawan, Provinsi Riau Menggunakan Data SAR

Indonesia merupakan salah satu negara yang memiliki potensi lahan gambut terluas di Asia Tenggara.. Pemanfaatan lahan gambut sebagai lahan perkebunan menimbulkan dampak lingkungan akibat aktivitas pembukaan lahan dengan metode drainase. Dampak buruk yang timbul salah satunya yakni penurunan permukaan lahan gambut. Penelitian ini bertujuan untuk mengetahui besar penurunan permukaan lahan gambut di Kabupaten Pelalawan, Riau menggunakan SAR dengan metode DInSAR. Adapun data utama yang digunakan dalam penelitian ini adalah citra satelit Sentinel 1-A, data orbit dan DEM SRTM 30 m. Adapun untuk mengetahui persebaran lahan gambut, digunakan Peta Indikatif Prioritas Restorasi oleh Badan Restorasi Gambut tahun 2015 sebagai data penunjang. Penelitian ini menggunakan metode two pass DInSAR sehingga menghasilkan dua data perubahan permukaan lahan. Pasangan citra bulan Juni 2015-Juli 2016 menunjukkan penurunan lahan gambut tertinggi sebesar 109,113 mm dan kenaikan permukaan lahan tertinggi sebesar 108,089 mm. Sedangkan pasangan citra kedua yakni bulan Juni 2016-Juli 2017 menunjukkan penurunan permukaan lahan gambut tertinggi sebesar 251,842 mm dan kenaikan permukaan lahan tertinggi sebesar 73,715 mm. ========================================================================================================= Indonesia is known as a country that has the largest peatland in Southeast Asia. Peatland is commonly used for agricultural, plantation and settlement purpose. The procedure for land clearing using drainage system leads to some problem such as Subsidence. Moreover, drainage in peatland can cause drought because of peatland characteristic that is not easily absorbing water after drying. This situation is very important to be monitored because the highest risk of forest fire is waiting. The aim of this research is to observe the land subsidence phenomenon on the peatland area in Pelalawan, Riau. This research uses the DInSAR method which needs SAR data such as sentinel 1-A, orbit, and DEM SRTM 30m. Using time interval 1 year between June 2015 until July 2017, DInSAR is used to detect deformation pattern in the imagery from Line of Sight (LOS). Map from Badan Restorasi Gambut is used as validation data to see the area which is recovered by peatland. There are 2 pairs of SAR imagery that is processed using the two-pass method to produce two imageries that reveal LOS displacement in every period. The first DInSAR (June 2015-June 2016) reveals that the highest subsidence is about 109,113 mm and the highest uplift is about 108,089 mm. Meanwhile, by the period, DInSAR in June 2016-July 2017 can be concluded that the highest peat subsidence is about 251,842 mm and the highest uplift is about 73,715 mm