Judul: Kajian Perubahan Tutupan Lahan Sub DAS Citanduy Hulu terhadap Kualitas Air Sungai Citanduy Hulu
Abstrak: Along with the growth of population, the need of areas for residential is also increasing which interfere the existence of forest along the river upstream areas. Land use changes which occured on the watershed indicates the decrease of water quality for example in Citanduy Hulu subwatershed. The aim of this research is to assess the changing of land cover, water quality and the relation between both aspects. Analysis which was used in this research are changes of land cover, and Index of Water Quality-National Sanitation Foundation (IKA-NSF) calculation. Land cover type in Citanduy Hulu subwatershed which decreased are forest (33.27%), bushes (45.25%), and waterbody (47.59%). Land cover type which increased are residential (107.88%), paddyfield (98.52%), dryland farming (26.97%), and open space (74.02%). The water quality of Citanduy Hulu river is categorized as good. The value of IKA on Citanduy Hulu river showed the tendency to decline from 73.16 in 2003 to 70.42 in 2011. The decrease of forest, bushes, and waterbody also the increase of residential, paddyfield, dryland farming and open space at Citanduy Hulu subwatershed caused the decrease of water quality at Citanduy Hulu river.
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Judul: Pengaruh Perubahan Penutupan/Penggunaan Lahan terhadap Karakteristik Hidrologi Sub DAS Ciliwung Hulu
Abstrak: Watershed is an ecosystem consisting of upstream, middle and downstream. Upstream watershed ecosystem is play an important role, because its function to regulate hydrologic characteristics of the watershed. Ciliwung watershed is one of the superpriority watershed that must be taken high priority effort to rehabilitation. According to Suripin (2002), hydrological components affected by development activities in the watershed includes surface flow coefficient, coefficient of discharge regim river, the ratio between maximumminimum river discharge, mud content or sedimentary deposits in the river, the rate of frequency and period of floods, and also the state of groundwater. The aim of the research is to analyze land use/cover, changes of land use/cover in upstream ciliwung watershed and to analyze its influence on watershed hydrology (flood and maximum-minimum river discharge). In this research landsat image of 1990, 2001 and 2010 was used to analyze the land use/cover changes. After that the condition of land use changes and characteristics of watershed hydrology were compared and evaluated. Based on image interpretation of land cover in 1990 and 2001, the area dominated respectively by dense jungle, mixed farms and tea plantation. While land use in 2010 is dominated respectively by dense jungle, tea plantation and settlement. Patterns of land use/cover change at period 1990-2001 indicates substantially conversion of agriculture land such as the rice field, dryland farming and mixed farms into settlements. Area that converted respectively are 238.8 ha, 238,5 ha and 127,8 ha. Bush land is transformed into agriculture land as well, which are tea plantation (180,1 ha), mixed farms (140,7 ha) and other agricultural cultivation. Mixed farms is the most intensively converted land into dryland farming (411,3 ha). In the period 2001-2010, pattern of landuse/cover changes that occured is not too different but in a much larger scale. Large conversion of agriculture land occurred toward settlement (rice field 231,3 ha, mixed farms 176,2ha and dryland farming 128,9 ha). Mixed farms was converted into dryland v farming are 329,5 ha and rice field 212,8 ha. Amount of bush land converted to tea plantation, rice field and dryland farming were respectivally 107,1 ha, 144,9 ha and 108,4 ha. A decline in the quality of the upstream ciliwung watershed hydrology can be seen from characteristic of flood frequency, the quality of a flood, maximum-minimum river discharge and the ratio between maximumminimum river discharge. Increase of settlement and dryland farming area in the upstream ciliwung watershed contribute to declining of upstream ciliwung sub watershed hydrology characteristics.
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Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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