Pemetaan kondisi hutan mangrove di kawasan pesisir Selat Madura dengan pendekatan Mangrove Health Index memanfaatkan citra satelit Sentinel-2

Abstrak. Pemetaan dan pemantauan kondisi hutan mangrove diperlukan untuk rehabilitasi dan konservasi lingkungan. Mangrove Health Index (MHI) menggunakan analisis citra satelit merupakan pendekatan baru yang bisa digunakan untuk mengetahui kualitas lingkungan ekosistem hutan mangrove. Penelitian ini bertujuan untuk untuk mengetahui struktur komunitas hutan mangrove dan melakukan analisis spasial-temporal MHI di kawasan pesisir Surabaya dan Sidoarjo menggunakan citra satelit. Data yang digunakan untuk analisis struktur komunitas mangrove pada penelitian ini adalah hasil pengamatan lapang di 10 transek. Untuk analisis MHI menggunakan citra Sentinel 2 perekaman tahun 2015, 2018, 2021. Hasil analisis menunjukkan bahwa spesies mangrove yang paling dominan di lokasi penelitian adalah Avicennia marina. Analisis citra satelit mendeteksi pertambahan luas mangrove yang signifikan dari tahun 2015 hingga 2021 yaitu lebih dari 500 Ha. Berdasarkan analisis MHI, terjadi perubahan positif dari kondisi hutan mangrove dominansi buruk (MHI 66,68%). Pertambahan luas hutan mangrove diiringi dengan perbaikan kondisi ekosistem dengan indikator meningkatnya MHI.Abstract. Mapping and monitoring the condition of mangrove forests is needed for environmental rehabilitation and conservation. Mangrove Health Index (MHI) using satellite image analysis is a new approach that can be used to determine the environmental quality of mangrove forest ecosystems. This study aims to determine the structure of the mangrove forest community and conduct a spatial and temporal MHI analysis in the coastal areas of Surabaya and Sidoarjo. The data used in this study were the results of field observations on 10 transects. MHI analysis using Sentinel 2 imagery recorded in 2015, 2018, 2021. The results of the analysis show that the most dominant mangrove species in the research location is Avicennia marina. Analysis of satellite imagery detects a significant increase in mangrove area from 2015 to 2021, which is more than 500 Ha. Based on the MHI analysis, there was a positive change from poor dominant mangrove forest conditions (MHI 66.68%). The increase in the area of mangrove forests is accompanied by improvements in ecosystem conditions with indicators of increasing MHI.

Spatio-Temporal Annual Changes of Mangrove Vegetation Coverages in Porong Estuary Based on Sentinel-2 Imagery

Mangrove is a typical coastal ecosystem with high productivity and has a number of ecosystem services. However this ecosystem is vulnerable particularly in urban areas due to land use change and illegal logging. Sidoarjo is one of the most developed urban area in the East Java Province, with mangrove ecpsystem scattered along the Porong estuary. This estuary is also the location of mudflow from the famous Lapindo mud disaster since 2006. This study aims to analyze the changes of mangrove coverages around the Porong estuary using satellite imagery data. Fractional Vegetation Coverage (Fv) was used to quantify the changes of mangrove vegetation coverage of Mangrove Forest from 2015 – 2021. The results show that there is a change in mangrove coverages in the area of study. The high change from lo vegetation coverage (LVC) to Full Vegetation Covarege (FCV) as found in the mouth of Porong River. This condition maybe caused by sedimentation process due to mudflow from volcanic disasters

Pemanfaatan Citra Satelit Aqua-MODIS untuk Pemantauan Dinamika Spasio-Temporal Produktivitas Primer Bersih di Perairan Laut Jawa

The Java Sea is an area with the highest rate of exploitation of fishery resources in Indonesia. As much as 32% of the total national fishery production or 2.2 million tons has come from catches in the Java Sea, even though the area of these waters only covers 7% of the total area of national waters. Fisheries productivity is related to the net primary productivity value resulting from the activity of phytoplankton or chlorophyll-a. Net primary productivity (NPP) is influenced by the presence of nutrients, light, chlorophyll-a, Photosynthetically Available Radiation (PAR) and sea surface temperature (SST). The purpose of this research is to analyze the distribution value of net primary productivity in the Java Sea by utilizing Aqua-MODIS satellite imagery using the Vertically Generalized Production Model (VGPM) method with a range of 2017-2021. The results showed that the waters of the Java Sea have quite high fertility and are classified as Eutrophic because the general monthly average from 2017-2021 has an NPP value of >750 mgC/m2/day. The value of primary productivity follows the seasonal pattern, will be high in the east moonson season and decrease in the west monsoon season. Laut Jawa merupakan wilayah dengan laju eksploitasi sumberdaya perikanan tertinggi di Indonesia. Sebanyak 32% dari total produksi perikanan nasional atau sebesar 2,2 juta ton berasal dari hasil tangkapan di Laut Jawa meskipun luas wilayah perairan ini hanya mencakup 7% dari total luas wilayah perairan nasional. Produktivitas perikanan tangkap berhubungan dengan nilai produktivitas primer bersih hasil dari aktivitas fitoplankton atau klorofil-a. Produktivitas primer bersih di suatu perairan dipengaruhi oleh adanya unsur hara, cahaya, klorofil-a, Photosynthetically Available Radiation (PAR) dan suhu permukaan laut (SPL). Tujuan dari penelitian ini adalah untuk menganalisis nilai distribusi produktivitas primer bersih di Laut Jawa dengan memanfaatkan citra satelit Aqua-MODIS menggunakan metode Vertically Generalized Production Model (VGPM) dengan rentang tahun 2017-2021. Hasil penelitian menunjukkan bahwa perairan Laut Jawa memiliki kesuburan yang cukup tinggi dan tergolong Eutrofik karena rata-rata bulanan secara umum mulai dari tahun 2017-2021 memiliki nilai NPP >750 mgC/m2/hari. Nilai produktivitas primer mengikuti pola musim, akan tinggi pada musim timur (kemarau) dan menurun pada musim barat (penghujan)

Seribu islands in the megacities of Jakarta on the frontlines of the climate crisis

Jakarta, the biggest city in Indonesia, has one district that consists of hundreds of islands that face severe climate hazards called the Seribu Islands complex. This study explores the evidence of local climate trends, the potential impact, and its policy intervention on Seribu Islands, which are classified as small island states and widely recognized as being especially at risk from climate change, threatening their economic and social growth. Long-term in-situ climate data, satellite data, interviews with local stakeholders, and literature reviews were utilized to conduct an exploratory descriptive analysis. The result revealed that Seribu Island experienced a 2.2°C increase in minimum temperature from 1980 until 2021, 3.5-fold of the frequency of extreme temperature and precipitation, 4.17 mm/year of sea level rise, and 10.8 ha land expansion in the densest island. Moreover, about 67% of the inhabitant’s islands were occupied by built-up areas that cover more than 50% of the region. Further, under the worst-case SLR scenario, about 58.4% of the area will be affected, and about 29 islands will disappear. This evidence was also reinforced by every single local respondent’s viewpoint who felt that climate change is occurring in the region. Even though the region faces a severe threat of climate change, the issue of climate change adaptation has not been mainstreamed yet into their local policy. Therefore, the urgency of a real-time climate ground station, a real-time early warning system, and establishing a Regional Disaster Management Agency (BPBD) at the district level have yet to be addressed. Furthermore, the knowledge gained from such case studies is outlined, along with some scientific evidence that may assist small island states in better fostering the opportunities provided by climate change adaptation

Mapping sea grass coverage of Tanjung Benoa Bali using medium resolution satellite imagery sentinel 2B

Seagrass beds are important components of a coastal ecosystem. This ecosystem serves as the primer producers of the water food chain, habitat for marine biota, produces organic carbon, and indirectly contributes to the economic well-being of coastal communities. However, the ecosystem is vulnerable to damage caused by natural factors and human activities. The objectives of this study were, firstly to identify the distribution of seagrass beds in Tanjung Benoa using Sentinel 2B satellite imagery and secondly to compare classification results from two different approaches namely pixel-based image classification and object-based image classification. Accuracy-test was carried out using field data reference of 195 sample points in the form of a 10 m X 10 m transect. The image pre-processing process was conducted with Bottom of Atmosphere (BoA) correction using the Dark Object Subtraction (DOS) method. Furthermore, the water column correction was performed using the Depth Invariant Index (DII) and the Lyzenga algorithm. The mapping results showed that the area of seagrass beds in the shallow waters of Tanjung Benoa reaches 242.99 ha. There were seven seagrass species in the study area, with an average cover of 75%. The accuracy of object-based image classification was higher than that of pixel-based classification with a difference up to 25% for six classes classification and 15% for two classes classification. Excellent results for classifying seagrasses based on cover density can be obtained when high-resolution satellite imagery and OBIA are combined with the SVM or Fuzzy Logic algorithm

Impact of the Strong Downwelling (Upwelling) on Small Pelagic Fish Production during the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean off Java

Although researchers have investigated the impact of Indian Ocean Dipole (IOD) phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) IOD phases on chlorophyll a (Chl-a) concentrations as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increase) in small pelagic fish production in the EIO off Java