CD Tesis

Studi Perubahan Garis Pantai Pada Lokasi Pembangunan Detached Breakwater Di Pulau Bengkalis

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Bengkalis Island is one of the two major islands in Bengkalis Regency. Based on data from the Badan Pusat Statistik Kabupaten Bengkalis, there are two sub-districts in Bengkalis Island: Bengkalis District and Bantan District with an area of 905.17 Km2. In the last 26 years there has been abrasion on Bengkalis Island with an average abrasion rate of 59 ha/year, and a sedimentation rate of 16.5 ha/year. This shows that the Bengkalis Island has experienced a significant reduction in land area with an average of 42.5 ha/year (Sutikno, 2014). The biggest level of abrasion occurs at the end of the eastern island (Nabilla et al., 2021). The location is in the northern of Bengkalis Island which is geographically directly facing with Malacca Strait. Therefore, many infrastructure buildings were built in order to protect coastline from abrasion, including detached breakwater and revetment structure. This research was conducted to analyze shoreline changes at the behind of detached breakwater structure, analyze the diversity of shoreline response at the behind of detached breakwater structure and analyze the geometric parameters that affect to performance of detached breakwaters.
The method used in this research is doing a survey at the location of detached breakwater and perform analyze shoreline changes using remote sensing with multitemporal Sentinel-2 satellite imagery data for 2016, 2018, 2020, and 2022. The shoreline was obtained by conducting a spatial analysis using the Modified Normalized Difference Water Index (MNDWI) method, while shoreline changes were analyzed using the Digital Shoreline Analysis System (DSAS) tool by comparing the coastline analysis results of MNDWI sentinel-2 satellite images before and after construction. Coastline changes are also directly observed using drones/UAVs (Unmanned Aerial Vehicles) which aim to be more convincing in the results of the analysis that has been done. Besides aiming to observe changes in the coastline, mapping by drone was carried out to obtain the layout and dimensions of the detached breakwater such as length of the structure (Ls) and the width of the gaps between the segments of the structure (Lg). This data used to analyze geometric parameters which affects the shoreline response behind detached breakwater structure. The results of this geometric parameter analysis are used to compare the response of shoreline changes at the location of detached breakwater structure with the existing literature.
The results showed the shoreline was changed in the behind of the detached breakwater structure with the largest shoreline retreat at the location 5 (Bantan Timur Village) with an average length change of 42,20 m and average abrasion rate of 15.50 m/year that occurs in the analysis of shoreline changes in 2020 and 2022. While the largest coastal accretion occurred at location 10 (Selat Baru Village) in the analysis of shoreline changes in the same years, 2020 and 2022 with an average length of forward change of coastline at this location about 87,90 m and an average accretion rate 32,28 m/year. The detached breakwater provides shoreline protection against abrasion and is effective in returning land as
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marked by an increase in land area from -10.713 Ha in the 2018 and 2020 shoreline change analysis to 12.757 Ha in the 2020 and 2022 shoreline change analysis. Based on the results of the shoreline response analysis at the end of 2022 review, it is known that the shoreline response varies in 35 segments from 12 locations. The 6 segments show good performance with tombolo formation response, 10 segments show good performance with the salient formation response, 11 segments showed poor performance with minimal formation response and the other 8 segments have not shown any performance in handling coastal protection which is marked by continuing abrasion conditions.
The suggestions for the research are (i) recommendations for improving the geometric parameters of the detached breakwater structure to performs well can be done by changing the length of the structure (Ls) or changing the gap distance between the segments of the structure (Lg) by increasing the length of the structure; (ii) shoreline change data for shoreline response analysis behind the detached breakwater structure is taken at least 1 year after construction in order to ensure that the detached breakwater structure has fully the function of returning shoreline position or land recovery due to abrasion; (iii) it is necessary to examine in more detail regarding the low threshold type detached breakwater (over topping) or the non overtopping type which can be used as additional parameters in analyzing the shoreline response behind the detached breakwater structure.
Keywords : Shoreline response, abrasion, accretion, detached breakwater performance

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Ketersediaan

Informasi Detail

Judul Seri

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No. Panggil

2110246881

Penerbit

Pekanbaru : Universitas Riau – Pascasarjana – Tesis Teknik Sipil., 2023

Deskripsi Fisik

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Bahasa

Indonesia

ISBN/ISSN

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Klasifikasi

2110246881

Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

TEKNIK SIPIL

Info Detail Spesifik

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Pernyataan Tanggungjawab

FATAH

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