Cikidang Fishery Port is one of the ports with serious abrasion and sedimentation problems. Seawater abrasion significantly affects some coastal areas that lack breakwater protection. Seawater abrasion causes the shoreline to recede further into the land, thereby narrowing the operational area of the coast. Not only that, harbour areas that are both protected and unprotected by breakwater also experience problems regarding water areas caused by ocean currents, tides, and large waves that lead to sedimentation. Sediment reduces the depth of harbour dock waters, making it impossible for ships to dock. As a fishing port that contributes significantly to the local economy, the Cikidang Fishery Port (CFP) necessitates analysis and solutions to address the issues of sedimentation and abrasion. References for this study used both primary and secondary data. We used a GPS handheld to measure the coastal area, and we conducted comparative studies using satellite images to gather secondary data. This will calculate the effective duration of the dredging process, enabling precise execution and minimizing the associated expenses.

Water resources play a crucial role in sustaining life and various socio-economic activities, especially in regions like South-Southern Nigeria, where petroleum production activities are prevalent. This study focuses on understanding the hydrochemical characteristics and geospatial distribution of major ions in water around selected petroleum-producing areas, notably within the Obigbo Local Government Area (L.G.A) of Rivers State. A total of 41 water samples, comprising 34 rain and 7 surface waters, were collected, and analyzed employing hydrochemical modeling techniques, including the Piper Trilinear plot, Durov, and Schoeller diagram, to characterize the ionic composition of surface water and rainwater. The analysis revealed a relatively uniform pattern of major ions, including Ca, Mg, Na, K, HCO3, Cl, SO4, and NO3, across the study area, with higher concentrations observed along the river channel, in the Northern regions. Rainwater samples exhibited lower concentrations, with discernible variations, especially in areas adjacent to petroleum activities. The dominance of Ca + Mg as cations and Cl as anions was consistent in both river water and rainwater samples. Durov diagram depicted a simple dissolution or mixing line in river water, while rainwater samples exhibited a notable presence of calcium and sulphate. The Schoeller diagram indicated a calcium chloride water type, with rainwater showing heightened calcium and sulphate concentrations. Geospatial analysis highlighted consistent ion concentration levels throughout the study area, suggesting environmental stability. Despite concerns about increased sulfate near petroleum facilities, all measured ion concentrations in both river and rainwater samples adhered to WHO standards, indicating satisfactory water quality.

3D modeling of buildings is an important method in mapping and modeling the built environment. In this study, we analyzed the differences between the semantic state of actual buildings and 3D models of LoD3 buildings generated using aerial and terrestrial photogrammetric methods. We also evaluated the accuracy of the visual representation as well as the suitability of the building geometry and texture. Our method involves collecting aerial and terrestrial photographic data and processing it using SFM (structure from motion) technology. The photogrammetric data was then processed using image matching algorithms and 3D reconstruction techniques to generate 3D models of LoD3 buildings. The actual semantic state of the building was identified through field surveys and reference data collection. The 3D building model was successfully modeled from 1201 photos and 19 ground control points. The results of the evaluation of the geometry accuracy test, dimensions and semantic completeness of the 3D model, the use of aerial photographs and terrestrial photogrammetry in LoD3 3D modeling are assessed from the results of the automatic 3D modeling process using SfM (Structure from Motion) technology that produces 3D building models in Level of Detail (LoD) 3 with Root Mean Square Error values <0.5 meters and has semantic completeness of the building in accordance with the original object based on the City Geography Markup Language (CityGML) standard. The facade formed from the modeling almost follows the original model such as doors, windows, hallways, etc.

In ocean remote sensing, the intensity of light entering the water column decreases exponentially with increasing depth due to scattering and particle absorption in the water column. This process of decreasing light intensity is called attenuation. Attenuation is a limiting factor in detecting objects in the water column and seafloor using remote sensing, which relies on light intensity. The attenuation coefficient (Kd) is an important optical property of seawater as it provides information about water clarity and the level of light attenuation. This study aims to analyze the estimation of the attenuation coefficient values and their variability using in-situ measurements and Sentinel-2 level 2A data in Karang Lebar, Pulau Panggang, and Pulau Air, in the Seribu Islands Regency, North Jakarta. We tested several algorithms to estimate the attenuation coefficient values. The research results show that the in-situ Kd and the estimated model values have a good correlation (r = 0.75-0.86). The distribution of attenuation coefficient values in the shallow waters of the study area ranges from 0.06 to 0.18m-1. The accuracy of estimating shallow water depth at the study sites was best represented by R2 and RMSE values in the range of 0-5m with an attenuation coefficient of 0.06-0.11m-1.
 
 Keywords: Diffuse Attenuation Coefficient, Remote Sensing, Sentinel-2 Imagery, Algorithm.

In general, the territory of Indonesia is prone to hydrometeorological disaster events. In disaster management, it is necessary to map the source or level of potential disaster hazards. The Analytic Hierarchy Process (AHP) method has been used to determine the relative importance of each criterion for potential mapping disasters. This literature study aims to determine the criteria and weighting in the AHP approach that can be used in assessing the potential for hydrometeorological disasters. This literature review is limited by analyzing and assessing the potential, vulnerability, and vulnerability of floods, landslides, and tornadoes using the AHP method. The input data used in the literature is based on the opinions of experts, interested stakeholders, and related regulations to determine the criteria and their weighting. The results of this literature review show that the three criteria are the dominant determining factors in assessing and analysing the three hydrometeorological disasters. The scoring of each criterion is based on its impact on the disaster.

Padang City is the capital city of West Sumatra Province which is located on the west coast of the island of Sumatra which is generally associated with tectonic earthquakes. This condition causes the city of Padang to become a disaster-prone area, one of which is land surface changes. The earthquake that occurred caused shocks to the rock and soil layers, causing water below the earth's surface to come out and resulting in changes to the soil surface. Besides, changes in soil surface are also caused by several things, including excessive groundwater extraction and soil type factors. To reduce the bad impacts, it is necessary to monitor the ground surface and to reduce the risk of a disaster. In a broad scope, the use of SAR imagery using the DinSAR method can monitor changes in the land surface in the city of Padang. The data used were Sentinel -1A imagery based on 3 earthquakes with a strength of more than 5 magnitudes centered on the Mentawai Islands, on September 8, 19, and 21 October 2020. From this research, the results obtained from the earthquake 8 September 2020 with satellite recording data 28 August (slave) and September 9, 2020 (master), there was land subsidence with a range of 0 - 25 mm along the coast of Padang City. The 19 and 21 October 2020 earthquakes with satellite recording data of 27 October 2020 (slave) and 15 October 2020 (master) obtained almost even surface subsidence with a range of 0 - 40 mm throughout the residential area of ​​Padang City.

The impact of sea-level rise is perceived by many archipelagic countries such as Indonesia. The higher the sea level rises every year, the larger the disaster threat in the coastal area. The current condition of most coastal areas indicates various pressures caused by city development, including the coastal area of Palopo City in South Sulawesi Province. The sea-level rise is suspected to be the cause of coastal inundation in Palopo City which, so far has not been identified. Therefore, this study aims to draw a coastal vulnerability map of sub-districts in Palopo caused by coastal inundation using GIS technology. Analysis of the areas affected by coastal inundation is carried out by processing spatial data. The sub-districts areas affected by coastal inundation are only those located in the coastal zones. The affected area in Bara, Wara Selatan, Wara Utara, Wara Timur, and Telluwana sub-districts are 160.64 ha, 21.41 ha, 73.55 ha, 87.56 ha, and 56.65 ha, respectively. In Bara Sub-district, the areas affected by coastal inundation are residential and mangrove conservation areas. The affected areas in Telluwana Sub-district are residential, production forest, coastal conservation, and mangrove conservation areas. The affected areas in Wara Selatan, Wara Timur, and Wara Utara Sub-districts are all residential areas. By using sea-level rise data of 27 years with its highest tide model, the coastal inundation in 2040 which is predicted to occur in Palopo City can be modeled properly.

The state of water quality around Panggang Island, Seribu Islands, in recent decades experienced degradation caused by human activities. The parameters of the diffuse attenuation coefficient (Kd) is an important optical property-related attenuation of light in the water column, and its brightness. Landsat 8 data has potential to map the value of Kd(490) in regional waters in Indonesia. Landsat 8 data could provide solutions to spatial data availability of Kd(490) values in addition to Ocean Color data. The purposes of this research was to developed empirical algorithm of Landsat 8 data to derive values of Kd(490) that can be use as tools for monitoring water quality optically on a regional scale which could not be done by Ocean Color data that has spatial resolution limitation. In-situ measurement of radiometric data was done by using TriOS-RAMSES hyperspectral spectroradiometer with a range of 320 – 890 nm and spectral sampling of 3.3 nm on shallow-waters around Panggang Island. The development of Kd(490) algortihm was done by simulation on ratio of Green and Near-infrared band has great determination values with Kd(490) empirically, which that empirical algorithm can be applied on Landsat 8 data to derive its values. In addition, it is noted that the shallow-waters around Panggang Island, dominant affected by absorption of chlorophyll-a rather than scattering by suspended solids.