Pemodelan Seamless Geoid Lokal di Wilayah Surabaya. Gresik dan Madura

Hamidatul, Aminah (2021) Pemodelan Seamless Geoid Lokal di Wilayah Surabaya. Gresik dan Madura. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Informasi Geospasial (IG) memegang peran penting dalam perencanaan tata ruang di suatu wilayah, ketersediaan IG yang berbeda-beda akan mengakibatkan adanya konflik batas wilayah dan menghambat pembangunan nasional. Dalam hal ini, Badan Informasi Geospasial (BIG) mendapat amanat dari pemerintah sebagai penyelenggara IG untuk mewujudkan Kebijakan Satu Peta atau One Map Policy. Peraturan terkait IG telah ditetapkan dalam UU No 4 Tahun 2011, dimana disebutkan bahwa Jaring Kontrol Gayaberat Nasional (JKGN) merupakan bagian dari Informasi Geospasial Dasar. Selain itu, Peraturan Kepala BIG (Perka BIG) No 15 Tahun 2013 tentang Sistem Referensi Geospasial Indonesia 2013 (SRGI2013) menyatakan geoid sebagai sistem referensi geospasial vertikal nasional. Peraturan-peraturan tersebut memperjelas pentingnya penelitian terkait pemodelan geoid di Indonesia. Penelitian kali ini bertujuan untuk membantu peningkatan model geoid di Indonesia dengan membuat model geoid lokal yang tersambung rapi (seamless). Model Geoid Indonesia telah dikembangkan sejak tahun 1997, namun hingga tahun 2015 belum mencapai ketelitian kurang dari 15 cm. Oleh karena itu, BIG memulai akuisisi data gayaberat menggunakan pengukuran terestris dan airborne gravity di seluruh wilayah Indonesia. Akuisisi data terakhir dilakukan pada tahun 2019 di Pulau Jawa dan NTT. Pulau Jawa menjadi fokus dalam penelitian ini, terutama di wilayah Surabaya, Gresik, dan Bangkalan. Pada lokasi tersebut, telah dilakukan pengukuran gayaberat terestris sejumlah 143 titik (Surabaya) dan 85 titik (Gresik). Selain itu, akuisisi data airborne gravity telah mencakup hingga Pulau Madura. Penelitian ini akan menggunakan data tersebut dengan penambahan data dari satelit altimetri dan model geopotensial global untuk melengkapi kesenjangan data gayaberat di darat dan laut. Komputasi data dilakukan dengan metode komputasi Least Square Collocation dan teknik Remove Restore untuk membentuk model seamless geoid lokal. Sedangkan, validasi geoid akan menggunakan titik pengukuran GPS/Levelling yang tersedia di Pulau Jawa untuk mengetahui ketelitian dari model. Model geoid lokal dibentuk menggunakan gabungan data gayaberat terestris dan airborne (Model 1). Selain itu, model seamless geoid lokal juga dibentuk menggunakan gabungan data gayaberat terestris, airborne dan marine gravity DTU (Model 2). Hasil uji statistik Model 1 mencapai akurasi 35,1 cm dengan ketelitian 8,4 cm. Sedangkan Model 2 menunjukkan akurasi sebesar 25,6 cm dan ketelitian 10,3 cm. Kedua model ini memberikan hasil yang lebih baik daripada model geoid global EGM 2008 yang memiliki akurasi sebesar 30,4 cm dan ketelitian 13,6 cm. Model geoid lokal yang dihasilkan masih memenuhi kriteria model geoid di Indonesia, yaitu dengan resolusi model sebesar 5’ × 5’ dan ketelitian kurang dari 15 cm. Nilai akurasi dan ketelitian ini dipengaruhi oleh jumlah data pengamatan gayaberat. Selain itu, jumlah titik untuk validasi juga memberikan peran penting untuk mendapatkan hasil model yang lebih baik. ================================================================================================ Geospatial Information (GI) has an important role in spatial planning in a region, the availability of different information will result in territorial boundary conflicts and hinder national development. In this case, the Geospatial Information Agency (BIG) received a mandate from the government as the organizer of the GI to realize the One Map Policy. GI-related regulations have been stipulated in Law No. 4 of 2011, which states that the National Gravity Control Network (JKGN) is part of Basic Geospatial Information. Besides, the Regulation of the Head of BIG (Perka BIG) No 15 of 2013 concerning the 2013 Indonesian Geospatial Reference System (SRGI2013) states geoid as a national vertical geospatial reference system. These regulations make clear the importance of research related to geoid modeling in Indonesia. This research aims to help improve the geoid model in Indonesia by making a seamless local geoid model. The Indonesian Geoid Model has been developed since 1997, but until 2015 it has not reached an accuracy less than 15 cm. Therefore, BIG started the acquisition of gravity data using terrestrial and airborne gravity measurements throughout Indonesia. The last data acquisition was carried out in 2019 in Java and NTT. Java Island is the focus of this research, especially in the Surabaya, Gresik, and Bangkalan areas. At that location, 143 points (Surabaya) and 85 points (Gresik) have been measured terrestrial gravity. In addition, the acquisition of airborne gravity data has covered Madura Island. This study will use this data with the addition of data from altimetry satellites and global geopotential models to complement the gaps in gravity data on land and sea. The data computation was performed using the Least Square Collocation computation method and the Remove Restore technique to form a local seamless geoid model. Meanwhile, geoid validation will use the GPS/Leveling measurement available in Java Island to determine the accuracy of the model. The local geoid model was formed using a combination of terrestrial and airborne gravity data (Model 1). In addition, a local seamless geoid model was also formed using a combination of terrestrial, airborne and marine gravity data from DTU (Model 2). The results of the statistical test Model 1 reached an accuracy of 35,1 cm with an accuracy of 8,4 cm. While Model 2 shows an accuracy of 25,6 cm and an accuracy of 10,3 cm. These two models give better results than EGM2008 global geoid model which has an accuracy of 30,4 cm and an accuracy of 13,6 cm. The resulting local geoid model still meets the criteria for the geoid model in Indonesia, namely with a model resolution of 5’ × 5’ and an accuracy of less than 15 cm. The value of accuracy and precision is influenced by the amount of gravity observation data. In addition, the number of points for validation also plays an important role in getting better model results.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Airborne, Gayaberat, Least Square Collocation, Informasi Geospasial, Model Geoid Lokal.
Subjects: G Geography. Anthropology. Recreation > G Geography (General) > G109.5 Global Positioning System
G Geography. Anthropology. Recreation > G Geography (General) > G70.217 Geospatial data
G Geography. Anthropology. Recreation > GA Mathematical geography. Cartography > GA139 Digital Elevation Model (computer program)
G Geography. Anthropology. Recreation > GE Environmental Sciences
T Technology > T Technology (General) > T57.5 Data Processing
T Technology > T Technology (General) > T57.62 Simulation
Divisions: Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geomatics Engineering > 29101-(S2) Master Thesis
Depositing User: HAMIDATUL AMINAH
Date Deposited: 22 Aug 2021 07:11
Last Modified: 22 Aug 2021 07:11
URI: https://repository.its.ac.id/id/eprint/88437

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