Analysis of East Surabaya Shoreline Determination Using Tidal Data, Image Satellite and RTK-GNSS

Abstract:

Coastal areas often experience changes in function, region supposed to be conservation area or coastal protection forests, as water catchment areas and habitats of mangrove forests have been turned into region large-scale housing, residential, industrial, ware housing and so on. Coastal area of Surabaya, especially in the East Surabaya, the reclaimed much influenced by several factors, including results from land fill for various purposes (residential areas, factories, bussiness and etc.) and caused by the sedimentation of the estuary lead the emergence of mainland. The impact of the reclamation both landfill or natural sedimentation certainly have an impact on shoreline.Based on the explanation of the law of local government No. 23, 2014 Article 6 [1], the meant of shoreline is the boundary meeting between the highest sea level and the mainland. The use of shoreline in this provision is intended for the determination of the administrative area in the management marine areas. Where is the position of the East Surabaya shoreline recentlyThis paper will answer the question to determine the East Surabaya shoreline using tidal data, image satellite and Real Time Kinematic-Global Network Satellite System (RTK-GNSS). The result can be used by Surabaya Government to manage buffer and marine zone especially in the eastern part of Surabaya.

• Periodical: Applied Mechanics and Materials (Volume 862)
• Pages: 41-45
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.862.41
• Online since: January 2017
• Authors: Khomsin Khomsin*
• Keywords: Coastal Area, Image Satellite, RTK GNSS, Shoreline, Tidal Data

References

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[8] proposed combination procedure between histogram thresholding and band ratio techniques to detect coastline. The accuracy of the extracted coastline has been estimated as 1. 3 pixels (pixel size=30 m). WorldView-2 is the first high-resolution satellite with 8 multispectral imaging bands. One of those is coastal band spectral (400 – 450 nm) which supports vegetation identification and analysis, and supports bathymetric studies based upon its chlorophyll and water penetration characteristics. Also, this band is subject to atmospheric scattering and will be used to investigate atmospheric correction techniques. WorldView-2 collects Panchromatics imagery at 0. 46 m at nadir and 0. 52 m Ground Spatial Distance (GSD) at 20 degress off-nadir and Multispectral imagery at 1. 84 m GSD at nadir and 2. 08 m at 20 degrees off-Nadir.

[9] In this study, WorldView-2 is obtained from Dinas Pekerjaan Umum Cipta Karya dan Tata Ruang (DPUCKTR) Surabaya which has been registered to Universal Tranverse Mercator (UTM) coordinate system. WorldView 2 in this study is recorded on November 11, 2012 at 10. 30 o'clock. It means that the condition of estern part of Surabaya waters in flood. GNSS-RTK Global Navigation Satellite System - Real Time Kinematic (GNSS-RTK) is a technique used to enhance the precision of position data derived from satellite-based positioning systems such as GPS (USA), GLONASS (Rusia), Galileo (Europe) and BeiDou (China). GNSS-RTK system uses carrier wave signal and relies on a single reference station to provide real-time corrections, providing up to centimetre-level accuracy. In practice, GNSS-RTK systems use a single base station receiver and a number of rovers. There are several ways to transmit a correction signal from base station to rover. Recently, the most popular way to achieve real-time, low-cost signal transmission is to use a Networked Transport of RTCM via Internet Protocol (NTRIP). NTRIP is a protocol for streaming differential GPS (DGPS) data over the Internet in accordance with specification published by RTCM. NTRIP is a generic, stateless protocol based on the Hypertext Transfer Protocol HTTP/1. 1 and is enhanced for GNSS data streams.

[10] In this case, Continously Operating Reference Station (CORS) at Geospatial Information Agency in Surabaya is as a base station. This station has a vertical reference which refer to high water level with connecting to BM 11. The problem is the height which is obtained from GNNS observation is ellipsoid height on World Geodetic System (WGS) 1984 not equal as HWL height. The relationship between ellipsoid height and orthometric height (in this case is HWL) is h = H + N (3) where h = ellipsoid height (WGS 1984) H = orthometric height (MSL/LWL/HWL) N = geoid undulation For the flat terrain and the distance one point to another point is less than 10 km, geoid undulation is relatively same value. Then, the formula in equation 3 can be modified to differential as follow: ∆h = ∆H + ∆N (4) and N value is relatively same, so ∆N = 0. Therefore the equation 4 can be as follow: ∆h = ∆H (5) and so the diffeence of height between point A and point B is ∆hAB = ∆HAB hB - hA = HB - HA HB = HA + hB - hA (6) This formula is used to calculate the elevation of CORS sattion and points of detail which refer to HWL. Therefore, GNSS-RTK rover surveyed at the elevation of land along the eastern coastal Surabaya to get some spot heights which have zero high water level (HWL = 0). Results and analysis Positioning to specify or describe the position of the shoreline refer to HWL on a map is determined by GNSS-RTK survey which refers to the reference vertical elevation determined from tide observations earlier (BM11). GNSS RTK result is in the form of spot height of land along the eastern coastal city of Surabaya with a corridor of 500 m landward. HWL shoreline has withdrawn following the elevation of pond dikes which have elevations between 0. 4 meters and 0. 9 meters to HWL. Therefore, the HWL shoreline depicted on the map is not a line with elevation of 0 m to HWL. Furthermore, GNSS-RTK is combined with satellite imagery worldview 2 and generated the eastern coastline of Surabaya as in the Figure 2. Figure 2. HWL Shoreline (red) in the East Coastal Surabaya The condition of the tide in the coastal of eastern part of Surabaya when the tide is highest can be observed easily in the field. It is caused by the coastal city of East Surabaya form is a large part of the dyke to the fish pond. Therefore, the condition of the sea water during high tide will not exceed existing fish pond dyke. Summary Data combination between tidal observation, GNSS RTK Survey and World View 2 in Surabaya can be generated to get shoreline which refer to high water level in the eastern part of Surabaya. The HWL shoreline is indicated by points located on the fish pond dykes which are closest to the sea during high tide. In this case, the heights of fish pond dykes are around 0. 4 – 0. 9 m from HWL. Referencees.

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