Judul: Perubahan Paras Muka Laut dan Dampaknya Terhadap Genangan di Daratan Pesisir Kota Semarang, Jawa Tengah
Abstrak: Sea level changing along the time with Mean Sea Level (MSL) shows increasing trend. Semarang City that facing subsidence also impacted by the change of sea level in term of sea level rise and tides. The recorded and reconstructed data (from CSIRO) shows that global sea level rose to 6.83 cm by Dec-2009. Regional sea level change data from University of Colorado also shows the increasing trend of sea level. Three months (Dec-2011 to Feb-2012) realistic tides model that has been generated using FVCOM shows the highest level of the sea surface was 0.473 m while measured sea level in coastal water area of Semarang City by 2010 was 94.669 cm. Measured sea level has to be corrected because the area where it measured experiencing land subsidence. Correction result shows isostatic mean sea level in 2010 was 52.070 cm. Subsidence rate in the location where sea level has measured (Tanjung Mas) can be estimate with the deviation between mean sea level data from tide gauge that experiencing subsidence and isostatic sea level. The result of estimation shows subsidence rate in Tanjung Mas is 7.1 cm/year. The impact of sea level change until 2011 has been formed 1,043.527 Ha of submergence area. Projection in the future shows that in next ten years submergence area will reach ± 3,627 Ha while in next 15 years submergence area will reach ± 4,364 Ha and in next 20 years submergence area will reach ± 4,641 Ha. When spring tides occur, the impact of sea level change will getting worst because area with altitude up to 0.47 from submergence area will be inundated by seawater.
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Judul: Spatial decision support system to coastal vulnerability analysis due to sea level rise and land subsidence at Semarang City
Abstrak: The relatively flat topography of Semarang has caused this city is vulnerable to sea level rise phenomenon. Various environmental problems faced by the city associated with coastal and ocean dynamics are tidal inundation, land subsidence, and flooding in rainy seasons. This study was conducted to (1) develop a spatial dynamic model of inundated areas due to sea level rise (2) map the coastal vulnerability due to sea level rise and land subsidence (3) prepare adaptive strategy to solve those environmental problems. Flash technology was used to model spatial dynamic distribution of inundated areas due to sea level rise. IPCC scenario at pessimistic and optimistic scenarios were combined with rate of land subsidence rates to predict an inundated scenario at the year of 2030. Adaptation strategy was developed by considering coastal vulnerability and adaptive capacity of the areas. Study results showed that the inundated areas at the year of 2010 were 1,231 hectares. Pessimistic sea level rise and land subsidence scenario showed that the size of inundated coastal areas of Semarang was 1,718.2 hectares, while pessimistic scenario showed an increasing inundated areas to 5,171.3 hectares. Fish-pond was the most extensive land use in coastal areas, as well as the most vulnerable areas to inundation. The inundated fish-pond areas in 2010 were predicted 272.8 hectares which would increase to 913.6 hectares in 2030. Potential losses derived from inundated areas would increase from IDR 3.7 T in 2010 to IDR 28.7 T in 2030. Adaptive capacity of villages in Semarang in 2010 was relatively high with low vulnerability level to inundations, whereas vulnerability level in 2030 tended to increase along with the extensification of inundated areas.
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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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