Journal of Applied Geospatial Information

Estimation of Attenuation Coefficient Values Using Remote Sensing and Its Relationship With Shallow Water Depth

Anggi Tiarasani, Vincentius Paulus Siregar, Jonson Lumban Gaol — Sun, 09 Jul 2023 00:18:05 +0000

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.

The Compatibility Study of Sentinel 1 Multitemporal Analysis For River-Flood Detection, Study Case: Bogowonto River

Sun, 09 Jul 2023 00:43:50 +0000

Flooding is a common natural disaster in Purworejo District, which can be caused by the overflowing of the Bogowonto River. The use of multitemporal analysis with Synthetic Aperture Radar (SAR) images, such as Sentinel-1, has the potential to aid in flood inundation detection for disaster mitigation in the area. However, there has not been any research examining the compatibility of flood inundation detection using multitemporal Sentinel-1 images with the flood susceptibility characteristics of the Bogowonto River. This study aims to evaluate this using a SWOT analysis. The results show that multitemporal analysis using Sentinel-1 images is not suitable for detecting flood inundation in the Bogowonto River due to difficulties in finding the right acquisition time at the time of the flood event. The duration of floods in the Bogowonto River is approximately 1-2 days, while the earliest reacquisition time for Sentinel-1 images for this study is 12 days. Additionally, Sentinel-1 images using band C have limitations in detecting floods under vegetation.

Diagenesis Analysis of Padengo Limestone Area, Gorontalo Regency Based on Petrographic Method

Fikri Boften, Aang Panji Permana, Muhammmad Kasim — Sun, 09 Jul 2023 07:34:23 +0000

Carbonate rocks are rocks composed of carbonate minerals that are chemically formed in the form of solutions, and there are organisms involved in their formation. The limestone found around Lake Limboto is very interesting, because the water in the lake is freshwater while the limestone is characteristic of a marine environment. Diagenesis is a natural process in sedimentary rocks that occurs from the initial deposition until it reaches the limit of metamorphism will be formed. The research area is located in Padengo Village, West Limboto Subdistrict, Gorontalo Regency with a research area of 7.72 Km². This research aims to analyze the diagenesis of limestone in the Padengo area of Gorontalo Regency using the petrographic method. The methods used are field geological survey and petrographic analysis. The results showed that the geology of the Padengo area is composed of a wackestone limestone facies unit, a crystalline limestone facies unit, and an alluvial sediment unit. The diagenesis type of the study area consists of neomorphism, micritization, dissolution, cementation, and dolomitization. From the type of diagenesis, it can be determined that the limestone diagenesis environment of the study area starts from the marine phreatic zone, then the burial zone, and ends at the meteoric vadose zone.

Application of Fixed-Wing UAVs to Develop Digital Terrain Model on Coastal Peatland Bengkalis Island

Hendra Saputra, Willy Okcandra, Sigit Sutikno, Muhammad Zainuddin Lubis — Sun, 09 Jul 2023 08:00:36 +0000

Destructive abrasion is currently occurring in Teluk Papal Village. The coast of Teluk Papal Village has a humus soil structure with soil conditions with a type of peat that is relatively easy to decompose. The cause is along the coast because of the absence of coastal protection plants (mangroves). To prevent the increasing abrasion rate, a comprehensive plan is needed by involving relevant stakeholders in both short and long-term planning. One of the efforts in controlling the abrasion rate is the construction of breakwater buildings. Before the construction is carried out, a study is needed to support the breakwater construction. One of the supports is to make a topographic or contour map. The field data acquisition process uses Unmanned Aerial Vehicle (UAV) technology. This data processing technique uses photogrammetric data processing techniques with the stages of flight path planning, measurement of Ground Control Point (GCP), and Benchmark points, which are then tied to BIG's CORS points to produce higher control point accuracy, Dense Cloud Point to create Digital Elevation Model (DEM) or Digital Terrain Model (DTM), and orthophoto embellishment. Furthermore, horizontal and vertical position accuracy tests were conducted using the calculation method issued by BIG regulation No. 15/2014 to provide information on how far the accuracy of the resulting map is. The results of the Digital Terrain Model (DTM) and orthophoto data accuracy test research based on the results of the accuracy test obtained a LE90 value of 0.6757 meters, then for the CE90 value of 0.1543 meters so that it meets the map requirements at a scale of 1:2500 at class 1 horizontal accuracy and class 2 vertical accuracy.

Keywords: Digital Elevation Model, Ground Control Point, Orthophoto, Topography, Unmanned Aerial Vehicle

Characteristics and Dispersion Model of Wastewater PT Kayu Lapis Indonesia, Kendal, Central Java

Mon, 14 Aug 2023 02:13:59 +0000

PT. Kayu Lapis Indonesia (PT KLI) is a company engaged in the forestry sector, particularly in wood processing. Production activities at PT KLI produce wastewater that is treated and discharged into the sea, and then spreads following ocean currents. This study aimed to analyze the characteristics of wastewater produced by PT KLI and predict the distribution pattern of the waste. The characteristics of the wastewater and seawater were obtained through in situ measurements and sampling, which were analyzed in the laboratory. The distribution pattern of wastewater discharge was modeled using the pollutant model from the hydrodynamic model results around the water. The characteristics of the PT KLI wastewater were dominated by parameters such as pH, biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), and total ammonia. The wastewater was processed in a Wastewater Treatment Plant (WWTP) until all the parameters met predetermined standards before being discharged into the ocean. The model results show that wastewater tends to move westward both at high tide in the west and east monsoons and at low tide in the west and east monsoons, with little movement to the east.

TSS (Total Suspended Soil) Analysis Using GEE (Google Earth Engine) Cloud Technology In Sibolga Waters

Mon, 21 Aug 2023 02:47:44 +0000

The TSS research using GEE Cloud Technology in Sibolga Waters was carried out from February to April 2021, Mey to July 2021, August to October 2021, and October to December 2021. The analysis was carried out using the Sentinel-2 Satellite. TSS results showed that the highest amount was 60-120 mg/liter and the lowest was 0-60 mg/l. The content of TSS is spread evenly around the edge of the Sibolga coast to the Middle of Sibolga Waters and has passed the quality standard limit according to the Minister of Environment of the Republic of Indonesia which means the Sibolga Water area is polluted and improper for drinking water as well as for fish cultivation. The result has been seasonal influence can determine the direction of the TSS distribution pattern, both tidal factors and weather conditions such as rain and dry season. The side effect on the TSS distribution pattern in Sibolga Waters causes the TSS value at high tide to be higher than at low tide. Sentinel-2 TOA Reflectance Data imagery can be used to map the TSS distribution pattern in the Sibolga Waters area.