Judul: Pemanfaatan Citra Landsat 8 Untuk Penilaian Vegetasi Sebagai Indikator Proses Degradasi di Daerah Karst Pegunungan Kendeng Utara
Abstrak: Karst area is generally has low agricultural productivity due to having poor soil. Intensive land use occured in the karst region of North Kendeng Mountains can be a threat for land degradation process or desertification in this region. The purpose of this study was to map land use, to assess land degradation by field, to assess vegetation index, to analyze land surface morphometry, and to assess dominant factor causing land degradation. Landsat 8 imagery was interpreted visually for producing land use map, while scoring and interpolation methods were used to assess land degradation degree. Several parameters for assessing it were the quality of vegetation, the rate of deforestation, the percentage of surface rocks, and the level of land management. The method of EVI, SAVI, II, TRVI, and NDVI were used for assessing the vegetation index through ENVI 4.5 software, whereas by SAGA software land surface morphometric has been analyzed, comprising slope steepnes, slope curvature, and surface roughness index. The decision tree analysis used for finding the dominant factor causing the land degradation. The results showed that the land use existing in the study area consists of forest (12.80%), mixed gardens (12.86%), settlement (4.66%), quary (0.13%), and dryland agriculture or tegalan (70.28%). The most dominant crop of tegalan was corn. Based on 71 sample points obtained, it indicated that the land degradation were dominantly taken place in western part of North Kendeng Mountain than the eastern part. According to the vegetation index, TRVI showed the best result for indicating the degraded land as shown of its high average value (0.2) and TRVI also exhibit better contrast color than others. The relationship between land surface morphometry and land degradation showed that the degraded land area was characterized by lower slope steepnes and have concave and not rude topography, otherwise the undegraded land were characterized by high slope steepnes and have convex and rude topography. According to decision tree analysis, TRVI was always on the primary node, while for combination of TRVI and morphometry showed that slope is in the second node. It indicates that TRVI and slope steepnes could be used for indicator for estimating land degradation in karst area. For study area its accuracy reaches 94.00%.
Keyword: Bogor Agricultural University (IPB), decision tree., morphometry, vegetation index, desertification, degradation

Judul: Metode deteksi degradasi hutan menggunakan citra satelit landsat di Hutan Lahan Kering Taman Nasional Gunung Halimun Salak
Abstrak: Indonesia merupakan salah satu negara yang mempunyai laju deforestasi yang tinggi yaitu 1,1 juta Ha/th (Dephut 2008). Indonesia telah mengakomodasi pentingnya pengurangan degradasi hutan untuk mengurangi emisi melalui Reducing Emissions from Deforestation and Forest Degradation (REDD) sejak tahun 2009. Deteksi degradasi hutan menggunakan teknologi penginderaan jauh masih menjadi masalah yang krusial untuk mendukung prosedur operasional monitoring, reporting and verification (MRV) REDD. Deteksi degradasi belum mempunyai metode standar klasifikasi perubahan kelas tutupan hutan pada citra maupun keadaan di lapangan. Berkenaan dengan hal tersebut maka pada penelitian ini dikaji beberapa metode klasifikasi berbasis piksel serta kelas-kelas degradasi hutan yang terukur dilapangan untuk deteksi degradasi hutan. Tujuan utama penelitian ini adalah mengidentifikasi metode dan membangun prosedur yang tepat untuk deteksi degradasi hutan. Tujuan khususnya adalah 1) mengidentifikasi peubah yang dapat digunakan sebagai indikator degradasi hutan di lapangan, 2) mengevaluasi tingkat akurasi klasifikasi kerapatan hutan menggunakan metode FCD, maximum likelihood, fuzzy dan belief-dempster shafer, 3) mengevaluasi tingkat akurasi deteksi degradasi hutan di Taman Nasional Gunung Halimun Salak (TNGHS). Metode deteksi degradasi hutan yang diuji adalah metode berbasis piksel dengan menggunakan metode post classification comparison (PCC). Metode klasifikasi citra yang digunakan adalah forest canopy density, maximum likelihood, fuzzy dan belief –dempster shafer. Metode identifikasi peubah kelas degradasi hutan dilapangan adalah dengan menggunakan analisis korelasi antara indikator tegakan yaitu volume, lbds dan kerapatan tegakan dengan indikator tajuk yaitu Crown Size Index (CDI), Crown Damage Index (CDI), Visual Crown Rating (VCR) dan Leaf Area Index (LAI) dan kerapatan tajuk. Uji hasil klasifikasi kerapatan hutan dan degradasi hutan menggunakan overall accuracy dan analisis Kappa. Hasil analisis regresi antara indikator tajuk dengan luas bidang dasar dan volume mempunyai koefisien determinasi yang rendah. Hasil analisis regresi antara indikator tajuk dengan kerapatan tegakan mempunyai koefisien determinasi yang lebih baik sehingga indikator kerapatan tegakan terpilih sebagai indikator deteksi degradasi hutan dilapangan.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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