The value of terrestrial carbon sequestration in urban areas, due to lack of vegetation as a carbon sink, is rarely studied. In fact, urban areas have high carbon emission values, which must be minimised. On the other hand, the value of carbon sequestration in urban areas is very dynamic due to natural factors from the environment and non-natural factors from anthropogenic activities. The main objectives of this study are to identify the carbon dioxide sequestration in urban areas, especially in tropical climates, and to determine the dynamics of carbon sequestration in urban areas for a year. The results show that carbon sequestration in tropical urban areas has a significant value compared with urban areas in temperate climates. This condition happens because there are still green open spaces in gardens and agricultural lands. The value of carbon sequestration in this tropical urban area experiences monthly dynamics caused by rainfall variation and anthropogenic activities, such as land conversion and plant type conversion in agricultural lands.

Karst especially tropical karst landscape has a potential value to store an amount of both organic and inorganic carbon. Tropical karst landscape can store organic carbon derived from forest ecosystem biomass that covers this karst landscape. While inorganic carbon stocks in tropical karst landscape are stored on carbonate rock (CaCO3). This potential can be calculated to identify the economic carbon value to support carbon trade program in East Kalimantan, Indonesia. This research aims to (1) identify carbon stocks value from organic and inorganic carbon in the study area; (2) calculate economic carbon value in the study area. Organic carbon stocks were measured using field measurement to calculate aboveground, belowground, and litter biomass. Calculation of aboveground, belowground, and litter biomass was measured based on the standard method in SNI 7724: 2011. X-Ray Fluorescence (XRF) method was used to identify the CaO concentration in carbonate rock. This CaO concentration was measured to calculate carbon (C) concentration in carbonate rock formation namely inorganic carbon stocks. Economic carbon value was calculated using cost-benefit transfer method. Biduk-Biduk Karst Region has a big value of organic carbon stocks of 0.007 Pg-C and inorganic carbon stocks of 9.02 Pg-C. Therefore, the total carbon stock in Biduk-Biduk Karst Region is 9.037 Pg-C. Based on the total value of carbon stocks, Biduk-Biduk Karst has a total economic value of US$ 45,171,544,296.

Indonesia is experiencing a rise in natural disasters due to its geographical position within a tropical region, with the Upper Solo River watershed exhibiting a heightened risk of flooding. This region has already suffered numerous floods due to excessive precipitation and insufficient drainage. Susceptibility, hazard, and risk studies have been conducted to investigate this phenomenon but have been limited to specific regions within the catchment area. This study aims to construct a GIS-based flood risk model using Open-Access Spatial Data (OASD) based on diverse physical characteristics, urbanization levels, and population. We used several OASD, including SRTM, Sentinel 2 MSI, GPM v6, NASA-USDA Enhanced SMAP Global Soil Moisture Data, GHS-SMOD R2023A - Global Human Settlement Layers, and GHSL: Global Population Surfaces 1975-2030 (P2023A). The model integrates the risk parameters to identify flood risk using a weighted overlay in ArcGIS. The results demonstrate spatial heterogeneity in flood risk throughout the watershed. The result also reveals that Surakarta City, with a high proportion of its area in the 'High' (57.3%) and 'Very High' (29.54%) risk categories, is at the highest risk of flooding within the watershed. The study enhances understanding of this topic by comprehensively evaluating flood hazards, vulnerabilities, and risks. It highlights the significance of utilizing low-cost OASD to improve flood preparedness and response strategies.

The watershed has many functions related to ecosystem protection. The existence of vegetation in the watershed can absorb some carbon from the atmosphere through photosynthesis. In fact, this carbon sequestration potential is declining due to vegetated land conversion phenomena. Therefore, monitoring carbon sequestration in this area needs to be done. However, it faces a problem due to the large size of the watershed area in a tropical region, so carbon sequestration cannot be measured by field-measurement. By combining RS and GIS, the carbon sequestration in a large watershed can be measured frequently to solve the problem. This research aims to analyze the dynamic change of carbon sequestration in Upper Bengawan Solo from 2000 until 2020. In this research, carbon sequestration was modelled using the Net Primary Productivity (NPP). NPP was measured by using the CASA method used Landsat Imagery and Meteorological Data from Meteorological Agency of Indonesia (BMKG). The results show that the carbon sequestration in Upper Bengawan Solo over 20 years decreased. The most significant decrease happens in the sub-urban area surrounding the urban area in Surakarta city. It indicates an environmental change in this watershed due to physical or human interference during this period. Meanwhile, by using RS and GIS, the spatial distribution of carbon sequestration change can be known, so it can be used to pinpoint the location which needs prior attention based on the higher level of these changes. This research implies that combining RS and GIS can help carbon sequestration monitoring be quicker and cost-limited.

The increase in carbon emissions in Indonesia is a problem that needs to be mitigated. One of the ways is to make an inventory of areas that have the potential to absorb carbon. One of areas that has the potential to absorb inorganic carbon is the karst area through the karstification process. However, research on inorganic carbon sequestration in karst areas, especially in tropical karst areas, is rarely studied. This potential needs to be studied to determine the important role of karst areas in efforts to reduce global carbon emissions. This study aims to identify the potential value of inorganic carbon sequestration; in Biduk-Biduk Karst Area and this efforts to reduce carbon emissions in Indonesia. Inorganic carbon sequestration was calculated based on the dissolution rate of carbonate rocks using standard limestone tablets. The efforts of karst areas to reduce carbon emissions was modeled by comparing the total value of inorganic carbon sequestration in karst areas with the value of carbon emissions in Indonesia. The results showed that the potential of the Biduk-Biduk Tropical Karst to absorb inorganic carbon is 726.864 tons/year-CO2. Inorganic carbon uptake shows variation based on differences in surface morphology, where areas with flat slopes have a higher inorganic carbon sequestrationn. This value can help to reduce carbon emissions in East Kalimantan by 7.3% and Indonesia by 0.5%. Therefore, conservation of karst areas is important to do to support carbon emission reduction programs in Indonesia.

Mangrove Segara Anakan merupakan salah satu ekosistem mangrove terluas di Pulau Jawa yang memiliki manfaat secara ekologi dan ekonomi. Pemanfaaatan ekosistem mangrove mendorong meningkatnya aktifitas manusia yang menyebabkan terjadinya penurunan luas ekosistem mangrove. Adanya aktivitas manusia dan perubahan lingkungan alami dapat menyebabkan degradasi yang pada akhirnya akan mempengaruhi kondisi kesehatan ekosistem mangrove. Tujuan dari penelitian ini yakni memetakan perubahan sebaran keberadaan dan kesehatan ekosistem mangrove di Segara Anakan, Kabupaten Cilacap pada tahun 2018 dan 2023. Sebaran ekosistem mangrove dimodelkan dengan metode klasifikasi Support Vector Machine (SVM). Uji akurasi dengan metode confussion matrix dilakukan pada hasil model SVM. Kesehatan ekosistem mangrove didekati dengan metode Mangrove Health Index (MHI) menggunakan empat indeks vegetasi yakni NBR, GCI, SIPI, dan ARVI. Hasil penelitian menunjukkan luasan ekosistem mangrove mengalami penurunan 883,28 Ha pada rentang tahun 2018-2023. Penurunan disebabkan karena adanya sedimentasi sungai dan perubahan lahan mangrove menjadi tambak. Kondisi kesehatan ekosistem mangrove tahun 2018 dan 2023 didominasi oleh kondisi kesehatan hutan mangrove sedang dengan luas 6.765,52 Ha pada tahun 2018 dan 5.058,36 Ha tahun 2023. Perubahan kesehatan ekosistem mangrove menjadi sangat baik banyak terjadi pada wilayah dekat Kota Cilacap dimana terdapat aktivitas konservasi dan rehabilitasi yang dilakukan oleh komunitas bersinergi dengan perusahaan dan pemerintah setempat.