Geospatial Information Agency Research Articles

The effects of DEM specification on watershed model in Mataram City, West Nusa Tenggara Province

One of data resources for hydrologic modelling is Digital Elevation Model (DEM). In hydrologic modelling, watershed delineation is an important step to create boundary of inundation area, so that DEM plays a significant role in watershed model. Nowadays, there are many sources of DEM data available in Indonesia that was provided by Geospatial Information Agency (BIG), including LiDAR and DEMNAS (National DEM). Based on its resolution, DEMNAS is classified as data for medium scale mapping, while LiDAR is used for large scale mapping. For hydrological modelling, medium scale data has been widely applied, while the large-scale hydrological modelling is still limited. The availability of large-scale data is quite large, including the City of Mataram, is a good source to examine its effect for hydrological modelling, so this research is conducted to see the effects of DEM sources, namely LiDAR and DEMNAS, for watershed model generation. Analysis is conducted by comparison to existing official watershed in that area. From seven watersheds, LiDAR produce better geometry in four areas, while DEMNAS is better in the rest. This research is expected to support a policy relating hydrological modelling at large scale.

Perubahan Spasial Wilayah Permukiman Muslim Sekumpul Terkait Aktivitas Dakwah KH Muhammad Zaini Abdul Ghani

Peran ulama sangat besar bagi masyarakat Kalimantan Selatan, tak hanya dalam aspek tatanan sosial kemasyarakatan tetapi juga dalam pembentukan cikal bakal permukiman Muslim. Penelitian ini mencoba mengidentifikasi pola perkembangan permukiman Sekumpul akibat aktivitas syiar KH Muhammad Zaini Abdul Ghani, serta identifikasi perubahan fungsi kawasannya berikut penerapan konsep Islam dalam penataan wilayah Sekumpul. Gambaran perkembangan deliniasi kawasan didapatkan melalui bantuan Google Earth dan Badan Informasi Geospasial Republik Indonesia, didukung dengan wawancara terstruktur terhadap narasumber kunci dengan menggunakan teknik snowball sampling. Hasil penelitian menunjukkan ekspresi perkembangan deliniasi spasial di kawasan Sekumpul berjalan natural dan mengadaptasi pola gurita dengan unsur jaringan jalan sebagai faktor dominannya. Dalam periode tahun 1990-an hingga saat ini kawasan Sekumpul telah tiga kali mengalami perubahan fungsi kawasan mulai dari fungsi pusat dakwah, fungsi hunian hingga fungsi ekonomi dengan konsep Religious tourismnya. Tidak ditemukan panduan spesifik terkait teknis pengembangan wilayah dalam materi kajian Majelis Arraudah, hanya pesan penting yang disampaikan oleh KH Muhammad Zaini Abdul Ghani adalah untuk memuliakan tamu. Konsep inilah yang menjadi pegangan warga Sekumpul Martapura dalam mengembangkan sarana fasilitas dan infrastruktur kawasan permukimannya

Numerical Simulation of Breakwater Layout in Puger Beach Jember Due to Tidal Wave

Puger Beach is located in the south Coast of Java Island which is directly facing the Indian Ocean. The ease of the ship to sail is influenced by the conditions of water in the port which caused by tides. The elevation of the crest of a breakwater is determined by the maximum high water level, while the depth of the shipping lane / port is determined by the minimum low water level. The purpose of this research is to evaluate the breakwater performance by analyzing the surface water level and flow velocity caused by tidal wave in Puger Beach using Delft3D-Flow. The bathymetry data obtained from BIG (Geospatial Information Agency of Indonesia) were utilized for the simulations. Tidal observation results from the previous study were used to validate the model. Two scenarios of breakwater layout were simulated. Spatial variation of flow velocities in the highest tide, the minimum ebb, and representative time steps for both cases are presented. It is shown that using the modified layout of breakwater, the flow velocities become smaller and more stable than that of the existing layout. Using breakwater in the right and left hand side of estuary, high velocities are able to be reduced. Based on the flow velocity pattern in five observation points and the water level, it is confirmed the modified breakwater layout of is more effective than that of the existing one.

Geomorphological Characteristic of Landslide Hazard Zones in Sukarame Village, Cisolok Subdistric, Sukabumi Regency

Geomorphology is the study of landforms, the processes of its formation, and the relations between forms and processes in their spatial order. Landslide is the movement of a mass of rock or earth from a higher place to a lower level due to the interaction of the geology structures, hydrology, and geomorphology. In a geomorphological unit, various aspects actively control the occurrence of ground movements. Knowing the geomorphological characteristics is crucial to identify a large estimation of the potential for landslides in the region. The Village of Sukarame is one of the villages in the Sukabumi Regency located on the slopes of Mount Halimun, whose territory is divided into west and east, separated by the Cisukarame River. Mapping the required geomorphological units Digital Data Elevation Model Indonesia (DEMNas) from the Geospatial Information Agency (BIG) is processed for altitude and slope data, as well as geological data and river data collected from BIG. Verification of landslide events through interviews and field surveys geomorphological unit analysis is done by overlaying and comparing the results of field observations. Also, a descriptive analysis is conducted by observing the map of landslide hazards zone from INARisk. The results show that the Village of Sukarame materialized from volcanic and fluvial origins. It has nine geomorphological units, which are the Hill Intrusion, Floodplain, Tapos Breccia Volcanic Plain, Citorek Tuff Volcanic Plain, Halimun Lava Slope, Tapos Breccia Slope, Citorek Tuff Slope, Fumaroles Plain, and Halimun Lava Field. Landslide-prone areas in Sukarame are in the geomorphological unit of Hill Intrusion, east of Halimun Lava Slope, Citorek Tuff Volcanic Plain, and along the river cliffs of the Cisukarame River and Cimaja River. The landslides occur naturally on the river cliffs of Floodplain and the cliffs of Citorek Tuff Volcanic Plain, which are dominated by sediments that cause the soil surface to become unstable. Moreover, anthropogenic activities, such as mining in the Hill Intrusion, also affect landslide occurrence in Sukarame.

Suitability of Nutmeg Plant Habitats in Three Nutmeg Production Centers using the Geographic Information System and Aster DEM in West Java, Indonesia

Nutmeg plant (Myristica sp.) produces seeds and mace as the main commodities of world spice trade. Nutmeg plant habitats in West Java are distributed mainly in Bogor, Sukabumi and Cianjur Regencies. This study aimed to determine the suitability of nutmeg habitats in three nutmeg production centers in West Java based on soil type and slope using the Geographic Information System (GIS) approach and Aster DEM (Digital Elevation Model) analysis. The study was conducted from August to December 2018, by collecting data of: a) The coordinates of the area planted with nutmeg using GPS (Global Positioning System), b) Field documentation in the form of descriptions around the data collection point, c) Soil analysis data, d) Land area data, e) Map of the earth scale of 1:50,000 scale from the Geospatial Information Agency, and f) Landsystem map of West Java scale of 1:250,000. Data were analyzed using Arc GIS 9.3. The results of land suitability analysis based on rainfall data for Bogor region was classified in the category of marginally suitable (S3), while the regions of Sukabumi and Cianjur were sufficiently suitable (S2). Temperature of Bogor region was categorized as the most suitable (S1), while Sukabumi and Cianjur regions were sufficiently suitable (S2) for nutmeg development. The distribution of nutmeg was in Latosol and Regosol soils, with soil pH of rather acidic (pH 4.78-5.98), clay texture, low to high C-organic content (1.5-4.5%) and moderate to high N-Total (0.2-0.5%). Cation exchange capacity ranged from 25-30 cmol(+)/kg with a base saturation level of around 55-60%. Based on slope, the distribution of nutmeg in the West Java region was in the range of slope with a flat (<8%) to sloping (8-15%) category, with altitudes between 400-900 m above sea level classified as suitable to very suitable for nutmeg development. The overall agroecological suitability of nutmeg plants in three nutmeg production centers in the West Java region was classified as suitable to be managed and developed.

Coseismic Displacement Accumulation Between 1996 and 2019 Using A Global Empirical Law on Indonesia Continuously Operating Reference Station (InaCORS)

Indonesia archipelago is one of the most populated country with active and complex tectonic zone in the world. Plate boundaries were assembled by four major plate which made the region not only vulnerable to earth-hazard but also prone to semi-dynamic reference frame. However, influence of transient deformation such as coseismic displacement due to large amount of small to intermediate earthquakes (< Mw 6) on the geodetic networks is remain poorly understood. Geospatial Information Agency occupied permanent and continuous GPS networks since 1996 but rapidly increase in 2010. Based on simulated empirical law of coseismic crustal deformation, we estimate the cumulative displacement due to coseismic step on Indonesia Continuous Operating Reference Stations (InaCORS). We utilize the position of the observation network and earthquake hypocentral with estimated moment magnitude. Our result suggesting small to intermediate earthquakes are indispensable for estimating secular motion and potentially contribute the cumulative offset associated with the transient postseismic deformation.

Crustal Deformation Studies in the Northern Part of East Java Derived from GPS CORS Data between 2015 and 2018

The tectonic setting of Indonesia is very complex due to its location on the boundaries of several major tectonic plates. The complexity of the tectonics also makes Indonesia prone to natural disasters such as earthquakes, tsunamis, and volcanic eruptions. Crustal deformation caused by the tectonics activities can be monitored using geodetic techniques such as Global Positioning System (GPS) and Interferometry Synthetic Aperture Radar (InSAR). In this research, we analyze the crustal deformation in the northern part of East Java using ten GPS Continuously Operating Reference Stations (CORS) data provided by the Indonesian Geospatial Information Agency from 2015 to 2018. The results showed the horizontal movement toward the southeast for all the stations. The horizontal velocity rates are range between 2.62 cm/yr observed at CPAS site, and 3.173cm/yr observed at CNGA station. For the vertical displacements, all the sites are subject to subsidence with the rates range from - 0.021cm/yr to -0.4 cm/yr that we suspect related to the geological settings of the study area. However, we found that the vertical annual time series of CMJT stations in 2015 are not consistent; this is because the antenna type was changed on the day of year (doy) 286 in 2015. On the other hand, the strain analyzes in the study area showed considerable compressional strain in the segment formed by three stations, namely CTBN, CSMP and CSBY which are located near to the Kendeng active fault.

Surface deformation and earthquake potential in Surabaya from GPS campaigns data

Study by the National Centre for Earthquake Studies suggests the presence of two segments of Kendeng active fault, namely Surabaya fault and Waru fault in Surabaya. This study aims to investigate the surface deformation and earthquake potential in Surabaya that possibly related to the activities of those two faults. We use GPS campaigns data conducted in March 2017, September 2017, May 2018, and October 2018 and five GGPS CORS stations around Surabaya provided by the Indonesian Geospatial Information Agency. In total, 21 GPS stations data were processed to obtain horizontal and vertical displacement velocities in each station. The results showed almost all stations move toward southeast with the velocity rates range from 1.034 cm/yr to 5.674 cm/yr, except BM33 and SB07 that moves northeast with the velocity rates 4.065 cm/yr and 3.312 cm/yr respectively. For the vertical displacements, almost all stations subject to subsidence with the rates range from -0.190 cm/yr to -5.769 cm/yr. Only three stations subject to uplift namely BM23 with the rate of 0.234 cm/yr, BM24 with the rate of 2.844 cm/yr, and BM29 with the rate of 3.33 cm/yr. The strain analyses showed large shortenings in the area between two faults with the values up to 11.95 μstrain. From the results, we can conclude that the surrounding area of the two faults have different deformation patterns, and by confirming with geological data, we suggest that Surabaya has an earthquake potential due to the active faults.

Effect of noises removal and spatial resolutions of Digital Surface Model (DSM) in flood inundation model

Digital Elevation Model (DEM) is an important component in flood inundation modelling as a part of flood risk analysis. However, Digital Surface Model (DSM) which still contains noises of artefacts is more common to be available than DEM. Then DSM misleads the inundation extent. This study will evaluate a measure to obtain a bare-earth surface (DEM) by developing and applying a workflow to remove the noises from DSM using simple tools available in the GIS computer software. The output of the method will then be used as input for flood inundation modelling of Semarang City in Indonesia. In addition to the main data set of TerraSAR-X DSM provided by Indonesia Geospatial Information Agency (Badan Informasi Geospasial or BIG), two sets of open source digital elevation data from Shuttle Radar Topography Mission (SRTM) and Advanced Spaceborne Thermal Emission (ASTER) are included in this study. The three data sets are processed and quantitatively compared. The results show that the applied noise removal method must be traded off with the lower resolution. Hence, the level of detail of particular flood inundation modelling will determine the required DEM resolution. Different study purposes will lead to different appropriate DEM resolutions to be used.

ANALISA HARMONIK PASANG SURUT DENGAN METODE ADMIRALTY PADA STASIUN BERJARAK KURANG DARI 50 KM

Pasang surut laut merupakan sebuah fenomena naik dan turunnya permukaan air laut di bumi akibat pengaruh gravitasi benda luar angkasa, terutama matahari dan bulan. Pengamatan pasang surut laut sangat penting dalam penentuan referensi vertikal, untuk menyatukan data-data pengukuran di laut dan di daratan agar dapat diterjemahkan dalam satu kesatuan sistem pemetaan. Indonesia sebagai negara kepulauan terbesar di dunia yang memiliki luas laut 3,25 juta km2 dari 7,81 juta km2 total luas wilayah Indonesia, sudah seharusnya memiliki stasiun pasang surut yang tersebar merata di seluruh Indonesia. Penempatan stasiun tersebut juga harus tepat lokasi karena setiap perairan memiliki karateristik tersendiri. Badan Informasi Geospasial (BIG) mengelola 138 stasiun pasang surut (pasut) yang terdistribusi di seluruh wilayah Indonesia. Stasiun pasut tersebut pada umumnya ditempatkan di dermaga/pelabuhan, sehingga jarak antar staisun pasang surut menyesuaikan ketersediaan dermaga yang ada. Pada penelitian ini dilakukan analisa harmonik pasut dengan metode admiralty pada stasiun pasut BIG yang jarak antar stasiunnya kurang dari 50 km, disumsikan tipe pasut di lokasi yang berdekatan tersebut sama. Lokasi penelitian adalah stasiun pasut Ulee Lhue dibandingkan dengan stasiun pasut Malahayati, stasiun pasut Pel. Ciwandan dibandingkan dengan stasiun pasut Serang, stasiun pasut Sunda Kelapa dibandingkan dengan Pondok Dayung, dan stasiun pasut Pameungpeuk dibandingkan dengan stasiun pasut Pamayangsari. Hasil penelitian menunjukkan bahwa tipe pasut dilokasi yang dibandingkan tersebut memiliki karakteristik yang sama.

Geometric Accuracy Assessment for Shoreline Derived from NDWI, MNDWI, and AWEI Transformation on Various Coastal Physical Typology in Jepara Regency using Landsat 8 OLI Imagery in 2018

Landsat 8 OLI imagery and water index utilization is expected to be able to complete the shoreline data that is difficult to obtain by using terrestrial and hydrographic surveys. In fact, coastal areas in Indonesia have a variety of coastal physical typology so that each water index characteristic in obtaining shoreline data needs to be understood in order to use water index method effectively. The objectives of this study are to map the shoreline using NDWI, MNDWI, and AWEI transformations and assess the shoreline geometric accuracy on various coastal physical typology. The shoreline derived from water index is obtained from Landsat 8 OLI imagery, while the reference shoreline for accuracy assessment is obtained from visual interpretation on Planet Scope imagery. Threshold 0 and subjective threshold based on per coastal physical typology sample experiments are used to separate land-sea. The horizontal accuracy standard of the shoreline derived from water index uses the regulation from Geospatial Information Agency of Indonesia No.15 in 2014 on technical guidelines for basic map accuracy. The results consisted of 1:100,000 scale shoreline map and shoreline geometric accuracy per coastal physical typology. Based on the shoreline geometry accuracy assessment, NDWI has the lowest shoreline geometry accuracy on artificial coast (RMSE=24.13 m). MNDWI has the lowest shoreline geometry accuracy on land deposition coast (RMSE=15.84 m), marine deposition coast (RMSE=29.53 m), and volcanic coast (RMSE=10 m). AWEIsh has the lowest shoreline geometry accuracy on the organic coast (RMSE=13.47 m), while AWEI does not superior to any coastal physical typology.

Pembentukan Peraturan Daerah Tentang Rencana Tata Ruang Wilayah (RTRW) Provinsi Riau: Dinamika dan Permasalahannya

Regional Regulation (Perda) is a regulation made by the Regional Head together with the DPRD that fulfills the elements of welfare and usefulness of a region. One of the Regional Regulations that has a strategic function is the Regional Regulation on Regional Spatial Planning (RTRW) because that is where land allocation is in accordance with the functions of the area regulated. However, the drafting of the RTRW Regional Regulation is not easy to differ from other local regulations because many interests must be considered and accommodated in its compilation including the drafting of the Riau Province RTRW Perda. After going through a very long process, the establishment of regional regulations was finally determined by The Governor of Riau, namely Regional Regulation Number 10 Year 2018 concerning the Riau Province Regional Spatial Plan with the following details: (1). Cultivation Area = 8,067,344 ha. (2). Protected area covering an area of ​​945,532 ha, with a total area of ​​9,012,886 ha. Although the Regional Regulation concerning the Riau Province RTRW has been established, there are still problems that must be resolved, namely concerning the emptying of areas that have become oil palm plantations in forest areas. This is not an easy job because it has to cut down oil palm trees with an area of ​​hundreds of thousands of hectares. Based on Law Number 12 Year 2011 there is no difference between the Provincial RTRW Perda and other Perda or having the same position both in terms of position and formation procedures. Whereas in the process of establishing a Provincial Regional Spatial Planning Regulation involving many agencies and ministries, among others, the Ministry of Home Affairs, the Ministry of Environment and Forestry, the Ministry of National Development Planning/BAPPENAS, the Ministry of Agriculture and Spatial Planning and the Geospatial Information Agency.

ASSESSING TIDAL FLOOD UPON SOLAR SALT FARMING AREA IN NORTH PART OF JAVA USING HYDRODYNAMIC MODEL

Abstract. This study aims to assess the impact of high tide upon salt production areas in north part of Java, Indonesia. Single case in June 2016 was applied using MIKE 21 in salt production area of Cirebon. The inputs are tidal height records, bathymetry, digital elevation model (DEM) from Geospatial Information Agency (GIA), and wind data from OGIMET. Peak water level from tidal constituent is extracted from the simulation. The exposed that were generated from peak level of water elevation showed that tidal event has led to 82.9% of salt production area being inundated. West and east part are recorded as the most affected location due to this extreme event. The maximum water level has reached about 38 cm and covered more than 6,489.38 ha during the tide. Whilst the accurate identification will provide valuable information for flood assessment upon marginal agriculture in coastal area.

Analysis CID Volcanic Earthquake in The Sunda Strait Due to The Eruption of Anak Gunung Krakatau

In earthquakes occur three types of waves, namely acoustic waves with vertical directions from the epicenter to the ionosphere F, gravity waves are waves generated from the tsunami, and the resulting Rayleigh waves move away from the epicenter. These waves create disturbances in the ionosphere, namely at electron density. The electron density in the ionosphere layer is called Total Electron Content (TEC). This phenomenon is detected as CID (Coseismic Ionosphere Disturbance), ie TEC fluctuations that occur ` 10 minutes after the earthquake. Earthquakes that are used as case studies are earthquakes that occur in the volcanic earthquake in the Sunda strait due to volcanic eruptions of krakatu children resulting in tsunamis on the Sunda Strait on December 22, 2018 (doy 356) with magnitude 5 SR at 13.55 UTC. In this study using the data of GNS (Global Navigation Satellite System) BIG CORS (Continuous Operating Reference Station) (Geospatial Information Agency uses CRKS, CPSR and CGON stations. The results of this study note that GPS number 3 detects TEC fluctuations after a volcanic earthquake. The biggest fluctuation worth 0.422 TECU which is at 9 minutes after the volcanic earthquake of the child of Mount Krakatau.

Evaluating GPS CORS Data for Crustal Deformation Analysis in East Java

The tectonic setting of Indonesia is very complex due to its location on the boundaries of several major tectonic plates. The complexity of the tectonics also makes Indonesia prone to natural disasters such as earthquakes, tsunamis, volcanic eruptions etc. Crustal deformation caused by the tectonics activities can be monitored using geodetic techniques such as Global Positioning System (GPS) survey, Interferometry Synthetic Aperture Radar (InSAR) processing, etc. In this research, we analyze the crustal deformation in the northern part of East Java using ten GPS Continuously Operating Reference Stations (CORS) data provided by the Indonesian Geospatial Information Agency from 2015 to 2018. The results showed the horizontal movement toward southeast for all the stations. The horizontal velocity rates are range between 2.63 cm/yr and 2.96 cm/yr. For the vertical displacements, nine stations are subject to subsidence with the rates range from -0.021cm/yr to -0.4 cm/yr that we suspect related to the geological settings of the study area.

The Republic of Indonesia Territorial Atlas as Geo-literation Tools for the Adolescents

Abstract. As an independent country and has a long history that forms The Unitary State of The Republic of Indonesia, introduction to the territory and history is very necessary for Indonesia's young generation, especially for adolescents. Various efforts were made by the Government of Indonesia to provide a territorial comprehension in order to make the younger generation understand about the circumstances of their country. One effective way is through Territorial Atlas of The Republic of Indonesia, which is the result from collaboration project between Geospatial Information Agency and Ministry of Education and Culture of Indonesia. This atlas is intended towards the benefit of teenage children, who are taking middle education level between the ages of 12–15 years. It is necessary for children at that age to be equipped with spatial intelligence related to the territorial comprehension of Indonesia, the historical development of the Republic of Indonesia, and also the natural resources potential of their country. This comprehension is needed considering that adolescence is a vulnerable age who require self-actualization, so they need to get a correct understanding of the NKRI region in order to foster the sense of nationalism. On the other hand, the important reason for production the Territorial Atlas is due to the rapid growth of development and the administrative area expansion, especially since the era of regional autonomy, was applied. Furthermore, another reason is that the atlases on the market were not up to date and geometrically did not obey the cartographic principle appropriately. This will cause a misconception for the reader, especially students in the middle school if they receive incorrect information. Therefore, it is important to produce a territorial atlas that uses the mapping principle and correct geospatial data and information. The method used in production the territorial atlas is using the GIS method complemented by literature studies and focused group discussions with education and geospatial experts. In general, the atlas is a compilation of coherent and comprehensive geospatial information regarding 34 provinces in Indonesia, the history of the Republic of Indonesia, introduction of neighboring countries and also equipped with narratives and interesting photographs/images. The results of this activity are in the form of The Republic of Indonesia Territorial Atlas which has been adjusted based on the applicable curriculum and will be disseminated to approximately 3,500 Junior High Schools in all regions of Indonesia in print and digital format. It is expected that through the atlas, the spatial comprehension of young people towards the NKRI region will be better and easier.

Implementation of CORS GNSS and local geoid for precise orthometric height determination in land subsidence region (a case study in Semarang City)

Geoid has an important role in converting geodetic heights to physical heights, both in orthometric height system and normal height systems. At present, Semarang City already has gravimetric geoid with centimeter-level precision. This gravimetric was validated by geometric geoid measured by static method. GNSS (Global Navigation Satellite System) measurement using static method needs long observation time and costly because it requires network that connect baselines and points. This study aims to implement CORS (Continous Operating Reference Station) GNSS in measuring geodetic height and to apply gravimetric geoid in orthometric height calculations. In this research, the gravimetric geoid recalculation process was carried out using gravity disturbance data of 2016. The geoid fitting process was carried out iteratively based on gravity data and modification of the integral of Hotine. Geodetic height measurements were carried out at 40 points distributed olong 50 km leveling network. Geodetic height measurements were refered to CORS GNSS of BIG (Geospatial Information Agency) and UNDIP (Diponegoro University) to produce standard deviation ranged from ±0.003 m to ±0.055. Geometric geoid checking with previous gravimetric geoid before fitting produced standard deviation of ±0.037 m and datum offset of -0.690 m. Geometric geoid checking for recent gravimetric geoid after fitting produces standard deviation of ±0.043 m and datum offset of -0.010 m. This study concluded that the refering geodetic coordinates to CORS stations by 1 hour observation of rapid static method and processing baselines in commercial software are sufficient for the determination of orthometric height in centimeter-level precision. This study also concluded that gravimetric geoid fitting based on gravity data shifting can minimize datum offset and shrinkage in geoid map.

PEMODELAN MIKE21 DALAM KEJADIAN BANJIR ROB MENJELANG GERHANA BULAN DI PESISIR SEMARANG

Pesisir Semarang merupakan wilayah yang rentan terkena dampak bencana banjir rob. Hampir setiap bulan wilayah tersebut tergenang akibat pasang air laut. Peristiwa banjir rob yang paling diingat publik adalah saat terjadi menjelang gerhana bulan tanggal 31 Januari 2018. Peringatan dini informasi banjir rob perlu dibuat dengan tingkat akurasi tinggi dan dalam bentuk yang mudah dipahami masyarakat untuk kepentingan mitigasi. Tipe pasang surut (pasut) di Pesisir Semarang perlu diidentifikasi untuk mengetahui kecenderungan waktu kejadian banjir rob. Model Hidrodinamika Mike 21 digunakan untuk mengolah data pengamatan pasut sepanjang tahun 2017 menjadi informasi prakiraan pasut sepanjang bulan Januari 2018. Nilai akurasi prakiraan pasut Mike 21 diukur dengan Root Mean Square Error (RMSE), serta dibandingkan dengan keakurasian prakiraan pasut dari Pushidrosal (Pusat Hidrografi dan Oseanografi TNI Angkatan Laut) dan BIG (Badan Informasi Geospasial). Hasil prakiraan pasut terbaik selanjutnya diolah pada aplikasi ArcGIS, dengan mengambil nilai prakiraan pasang tertinggi pada hari kejadian sebagai data input untuk pembuatan peta luas genangan banjir rob. Puncak kejadian banjir rob cenderung terjadi pada pukul 06.00 WIB dan 17.00 WIB, yang mana berdasarkan hasil identifikasi di Pesisir Semarang termasuk tipe pasang surut harian ganda. Prakiraan pasut dari Mike 21 memiliki nilai RMSE terbaik. Nilai RMSE prakiraan pasut Mike 21, Pushidrosal dan BIG berturut-turut bernilai 10 cm, 30 cm dan 22 cm. Nilai pasut tertinggi baik model Mike 21 maupun hasil pengamatan terjadi pukul 20.00 WIB. Pemodelan nilai pasut tertinggi dari Mike21 sebesar 122 cm menghasilkan peta luas genangan banjir rob sebesar 1753.35 ha, sedangkan nilai pasang tertinggi hasil pengamatan sebesar 133 cm menghasilkan 185.31 ha lebih luas.

Analysis of sea level rise and tidal components based on satellite altimetry Jason-2 and tide gauge data in 2008-2016 in Sunda Kelapa

In this study, Sea Level Anomaly based on the tide gauge and satellite altimetry measurements are used to analyze Sea Level Rise (SLR) and tidal component in Sunda Kelapa Waters for 9-years. The satellite altimetry data uses data from AVISO and Tide Gauge data is obtained from BIG (Geospatial Information Agency of Indonesia). This study uses the least square analysis method to know the value of SLR, and harmonic analysis method to know the type of tidal along with tidal components value in Sunda Kelapa Waters. SLR analytic result in Sunda Kelapa based on satellite altimetry Jason-2 show increase in 0.00342 meters / year. Sunda Kelapa Waters can be classified as having mixed single dominant tides on January - June and diurnal tides on July-December. Tidal component in Sunda Kelapa Waters with tide gauge observation resulted average value of Z0; 0.1501 m, M2; 0.0062 m, S2; 0.0086 m, N2; 0.0022 m, K2; 0.0045 m, K1; 0.0240 m, O1; 0.0093 m, P1; 0.0106 m, M4; 0.0011 m, and MS4; 0.0011 m.

Optimization of Ground Control Point (GCP) and Independent Control Point (ICP) on Orthorectification of High Resolution Satellite Imagery

In the rapidly evolving technology era, various survey methods have been widely used one of them by remote sensing using satellite. It is known that the satellite image recording process is covered by rides (satellites) moving over the Earth's surface at hundreds of kilometers, causing satellite imagery to have geometric distortion. To reduce the effect of geometric distortion of objects on the image, geometric correction by orthorectification is done. Pleiades is a satellite of high resolution satellite image producer made by Airbus Defense & Space company. The resulting satellite imagery has a 0.5 meter spatial resolution. As a reference for the more detailed space utilization activities of space utilization arranged in the Regional Spatial Plans, Detailed Spatial Plans was created with the 1: 5000 scale map which has been governed by the Geospatial Information Agency. In the process of orthorectifying satellite imagery for this 1: 5000 scale map, ground control or Ground Control Point (GCP) is used for geometric correction and Digital Elevation Model (DEM) data. In this research, the optimal number of GCP usage for orthorectification process in Rational Function method is 21 GCP using 2nd order polynomial