Alan F. Koropitan
Departemen Ilmu dan Teknologi Kelautan, FPIK-IPB, Bogor

Published : 5 Documents

Found 5 Documents

Jurnal Ilmu dan Teknologi Kelautan Tropis Vol 7, No 1 (2015): Elektronik Jurnal Ilmu dan Teknologi Kelautan Tropis
Publisher : Jurnal Ilmu dan Teknologi Kelautan Tropis

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Study on tidal waves and residual currents in Mayalibit Bay was conducted by constructing the 2D numerical hydrodynamics to find the characteristics of tide and residual currents inside the Bay. The 2D hydrodynamic equations with non-linier terms were solved by finite difference methods explicitly. M2 and K1 wave propagations were observed and analyzed at 25 observation points. M2 and K1 residual currents were obtained and described spatially. Simulation results of tidal currents were validated with field measurements. The validation result showed that the tidal currents between the model results and field measurements were quite fit. Generally, simulation results showed the significant differences between the tide inside and outside the Bay. This was strongly explained by the simulation results of M2 and K1 wave propagations. The M2 and K1 amplitudes were 10 times lower inside  than outside the Bay with the phase lags of about 180°(M2) and 160°(K1). This result indicated that the tide inside and outside the Bay were in the opposite conditions. The tide had an ebb inside while the flood was outside and vice versa.  M2 residual currents was flowed into the Bay uniformly, while K1 residual currents flowed out to the open sea in the Northern part and it flowed into the Bay in the Southern part of the Bay. Eventually, both of them converged in the middle of the Bay. Keywords: tide, tide-induced residual current, numerical method
Primary Productivity of Jakarta Bay in A Changing Environment: Climate Change and Anthropogenic Impacts Siregar, Vincentius; Koropitan, Alan F.
BIOTROPIA - The Southeast Asian Journal of Tropical Biology Vol 20, No 2 (2013)

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Jakarta Bay receives direct impact from the rapid development of infrastructure and landbased industries which contributed to the increase in pollution and nutrient, and at the same time facing climate change. This condition influenced growth of chlorophyll- and primary production. To investigate changes of primary production in Jakarta Bay due to anthropogenic and climate change impacts, a field measurement, laboratory experiment and collection of several data sets have been conducted. The study showed that impact of anthropogenic, particularly sediment load from the land to primary production is important. The intensification of primary production occurs in the middle region of Jakarta Bay, while the chlorophyllconcentration is high in the river mouth area. The anthropogenic impact is indicated by the land use change that has increased to 73% during the last ten years. The laboratory experiments by injecting CO in the waters, as a global warming simulation, have shown a decrease in chlorophyll- and primary production. Therefore, the combination of anthropogenic and climate changemay have a double impact on the Jakarta Bay ecosystem.Key words: Primary production, Jakarta Bay, anthropogenic, climate change, impact
COHESIVE SEDIMENT TRANSPORT MODELING ON INNER AMBON BAY Noya, Yunita A.; Purba, Mulia; Koropitan, Alan F.; Prartono, Tri
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol 8, No 2 (2016): Elektronik Jurnal Ilmu dan Teknologi Kelautan Tropis
Publisher : Bogor Agricultural University

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The presence of cohesive sediment in the water column can reduce light penetration and affect photosynthesis process, and it can be disrupted the primary productivity of aquatic, and sedimentation of coastal waters. The objective of this research was to determine the cohesive sediment distribution pattern and the relationship with sedimentation. MIKE 3 FM modeling was used to understand the process of sediment transport and sedimentation on Inner Ambon Bay. Sediment transport modeling method was divided into two stages: the hydrodynamic modeling (baroclinic) and sediment transport (mud transport) modeling. The model results indicate current patterns in the Inner Ambon Bay is influenced by the tidal factor. Suspended sediment dispersed vertically from the surface to a depth of 30 m with concentration of about 3.5-15 Kg/m3. The maximum consentration of the suspended sediment occurs at head of the bay (around Waiheru, Passo, and Lateri). Model simulations for 30 days showed the rate of erosion is about 1.04-6.15 Kg/m2/s, while in Inner Ambon Bay the erosion about 9.07x10-8Kg/m2/s only occurred in T1 station. Sedimentation associated with the cohesive sediment accumulation and it was shown by bed level. In addition, the simulation showed bed level in sill ranged at 0.01-0.19 cm and 0.47 mm/day on average, while in the Inner Ambon Bay it ranged from 1.75-10.01 cm, and the sedimentation rate was approximately 39.9 mm/day.
Analisis Diagram T-S Berdasarkan Parameter Oseanografis di Perairan Selat Lombok Harvianto, Loecky; Parengkuan, Maxi; Koropitan, Alan F.; Agustiadi, Teguh
Surya Octagon Interdisciplinary Journal of Science and Technology Vol 1 No 1 (2015): SOIJST
Publisher : Surya University

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Research of water masses by using conductivity temperature depth are conducted in the Lombok Strait during September 2014 under the Cruise SITE Leg II to Lombok Strait. The aim of the research is to investigate Temperature-Salinity Diagram based on oceanographic parameters in Lombok Strait. Temperature-Salinity Diagram shows the origin of the water masses across Lombok Strait. The results of this research shows water masses across Lombok Strait comes from North Pacific Subtropical Water (NPSW) on ~ 150 m depth and North Pacific Intermediate Water (NPIW) on ~ 400 m depth. The differences values of salinity reference and salinity measurement indicates the properties of NPSW and NPIW are dynamic, verified by the number of salinity reference is 34,55 Psu on ~ 150 m depth, whereas the salinity number of five station in order are  34,63 Psu; 34,65 Psu; 34,65 Psu; 34,57 Psu; 34,52 Psu. The difference of salinity number caused by strong vertical mixing in Indonesian waters.
Marine Research in Indonesia Vol 44 No 1 (2019)
Publisher : Research Center for Oceanography - Indonesian Institute of Sciences (LIPI)

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The present study aims to investigate the influence of oceanographic factor and riverine input on  mangrove ecosystem and their ability in  absorbing carbon. The location of the study was conducted in two different locations in West Kalimantan, which are (1) Mempawah and (2) Bakau Besar. The sediment sampling was carried out using PVC pipes in the middle of the transect point and taken within ± 20 cm depth. After laboratory pre-treatment, we analyzed the carbon content using CHN Analyzer. The results showed that station 3 of Mempawah and station 2 of Bakau Besar have a high organic carbon content, i.e., 6.46 ± 0.23 ton C/ha and 14.93 ± 1.43 ton C/ha, respectively. We also found that input organic carbon in the river (location 2) and canal (location 1) were higher at high tide than low tide. Besides that, we also found that the sediment type at station 3 of Mempawah is categorized as silt (75%) and fine sand (± 0.24%). Whereas at station 2 of Bakau Besar, the sediment contains silt (68%) and fine sand (± 2%). In addition, those two stations have a total mangrove density up to 13519 individuals/ha and 9928 individuals/ha, respectively. According to this findings, we suggest that high organic carbon is influenced not only by high biomass density but also by the oceanographic factor that affects load of organic carbon in river and canal, and the difference of sediment types that are influenced by breaking wave height at the study site. Keywords: mangrove ecosystem, organic carbon, oceanographic factor, West Kalimantan