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: Identifikasi Perubahan Tutupan Lahan Menggunakan Citra Landsat Multiwaktu dan Teknologi Sistem Informasi Geografis (SIG) di IUPHHK-HA PT. Austral Byna Kalimantan Tengah
Abstrak: The utilization of forest by Forest Concessions (HPH) or now known as The Forest Utilization License Timber-Forest Nature (IUPHHK-HA) brings many benefits but it also brings a downside for the Indonesian forestry. This activity has increased economic and regional development, but also lead to greater rates of deforestation and forest degradation as well. In general degradation that occurs in production forests result in damage or reduction of productive forest area to total forest area that will affect productivity. The negative impact of deforestation and degradation can be minimized through the efforts of a fast and efficient monitoring using remote sensing. Digital imagery or remote sensing data is one of the data to analyze the surface of the earth. Ministry of Forestry using Landsat imagery as one tool in monitoring the condition of Indonesia's forests. Landsat multi-time combined with Geographic Information Systems (GIS) facilitate the monitoring process. Both long-term monitoring and short-term monitoring can be controlled so that the rate of deforestation. This study aims to identify land cover classes as well as changes in the PT. Austral Byna in 1997, 2005 and 2012, and calculate the rate of degradation and reforestation arising from the use of forests in the periode of observations. The experiment was conducted in two phases, field phase in April-May 2012 in PT. Austral Byna, and image processing in June to November 2012 in the Laboratory of Remote Sensing and GIS Department of Forest Management Fahutan IPB. The data used are Landsat TM and ETM+ 30 m resolution coverage in 1997, 2005 and 2012 as well as other supporting digital maps. The tools used in the form of PC with the software ArcView 3.2, ArcGIS 9.1, Erdas 9.1, GPS, Camera and stationery. The result showed that successfully classified land cover both digital and visual consists of forests, fields, bushes, farm, vacant land and clouds. Degradation of the highest in 1997, 2005 and 2012 occurred in the class turned into a forest shrubs. While reforestation occurred in the highest class of the field and forest shrubs that turned into a forest.
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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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