Vertical accuracy in DEM (Digital Elevation Model) products is very important for an earth study. There are medium resolution DEM data products that can be accessed freely such as DEMNAS, Alos Palsar 12.5m and Sentinel-1. The aim of this study is to measure the vertical accuracy of the DEMNAS, Alos Palsar 12.5m and Sentinel-1 data products by considering the slope angle classification and using two different GIS software. Vertical accuracy is measured using 848 spotheight points, by calculating the RMSE (Root Mean Square Error) value of each DEM product with different software. Based on the research, it was found that DEMNAS is a DEM product that has the best comparability value than Alos Palsar and Sentinel-1, because it has the smallest RMSE value. Slope angle class gives different values of bias against absorption and reflection of electromagnetic waves. Flat to moderate steep slope angles tend to be better at absorbing and reflecting electromagnetic waves. The software differences in the analysis did not significantly affect the altitude of the DEM and RMSE high points. The spotheight point needs to be reaccurated with a more detailed geodetic point, to get maximum results.
Tujuan dari penelitian ini adalah melakukan pemetaan kerapatan kanopi vegetasi tegak di Sub DAS Bompon, dimana penggunaan lahan vegetasinya berupa kebun campuran dan hutan rakyat sehingga vegetasi tegak pada wilayah ini adalah sangat heterogen. Penelitian ini menggunakan beberapa indeks vegetasi dari citra satelit Sentinel-2 juga membandingkan metode pengukuran kerapatan kanopi dari hemispherical photography (pemotretan keatas) dan UAV (pemotretan kebawah). Tahapan penelitian meliputi pra-pengolahan citra Sentinel-2 dan membangun transformasi indeks vegetasi yaitu RVI, NDVI, SAVI, ARVI dan EVI. Dilanjutkan dengan pengumpulan data kerapatan kanopi, analisis regresi linier dan membangun peta kerapatan kanopi dari persamaan regresi linier antara indeks vegetasi dengan nilai kerapatan kanopi. Hasil penelitian menunjukkan bahwa NDVI merupaka indeks vegetasi terbaik untuk pemetaan kerapatan kanopi di Sub DAS Bompon. Hal ini dikarenakan indeks tersebut memiliki korelasi terbaik dan RMSE terendah setelah dijadikan peta kerapatan kanopi dari data UAV.
This study was conducted to compare the performance of three different spatial analysis models: Inverse Distance Weighted (IDW), Ordinary Kriging, and Regularized Spline interpolation technique to determine the best fit model representing Peak Ground Acceleration (PGA) in West Java Province, Indonesia. The three models are commonly used in spatial visualization, but have different calculation methods. The calculations were performed using available formulas while the spatial modeling was conducted using the algorithms in GIS software. Meanwhile, the accuracy of the spatial model and factual calculation was determined through the Root Mean Square Error (RMSE). The results showed differences for both spatial distribution and maximum and minimum values for each model. However, IDW was observed to be the model which approaches the factual value of the PGA calculation as indicated by its RMSE value of 0.772352 in comparison with the 7.169879 (Ordinary Kriging) and 1.140802 (Regularized Spline).
Current sustainability assessment methods are mostly disseminated at global or national scales. However, the sustainability criteria often fail to capture many ecological characteristics that are important to the local population. This article aims to understand the importance of ecological criteria for sustainability by reviewing the literature on issues related to the implementation of ecological criteria on global, national, and local scales. This study uses qualitative content analysis by examining secondary data searches such as journal articles and research reports regarding the topics. We use NVIVO software for theme coding. We also use a case study in the oil palm plantation in Belitung Island and the Indonesian palm oil sector to see how global and national ecological criteria for sustainable palm oil were designed and whether it is adaptable to the local context. This study reveals three main themes namely the function of ecological criteria and indicators, the adaptation of global and regional criteria, and the importance of local characteristics and value. We concluded that although global and national criteria for sustainable palm oil have been established, the characteristics of local biodiversity and social value and its prioritization are needed to ensure sustainability reached the lowest scale.
The Northern Bandung area covers two landforms, namely volcano and structural landforms. Unconfined groundwater has become the water source for local people’s daily needs in both landforms. It is necessary to map the potential unconfined groundwater for both volcano and structural landforms due to the significant role of springs for the local people living in those areas. This research aims to map the unconfined groundwater on the volcano and structural landforms. This study employed the approaches of Analytical Hierarchy Process (AHP), Geographic Information System (GIS), and Remote Sensing (RS) using the variables of lineament density, rainfall, slope, and Topographic Wetness Index (TWI), hydrogeology, drainage density, and land use. The result shows that each variable has the Consistency Ratio (CR) below 0,1, resulting in consistent research variables and appropriate for discussion. The classification of the potential groundwater is divided into three categories: low, medium, and high. The survey validation finds that 147 springs spread at 86 high lands, 55 medium lands, and six lowlands. This model can be an alternative to map the potential unconfined groundwater in both volcano and structural areas.
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