Judul: Planned Flood Discharge Analysis and Efforts to Reduce Runoff in Ciherang Sub-watershed, Cisadane Watershed
Abstrak: Sub-DAS Ciherang memiliki tutupan lahan yang didominasi oleh sawah dan perkebunan yaitu sebesar 539.2 ha dan 464.18 ha serta curah hujan bulanan yang tinggi pada bulan November sampai dengan Maret. Penelitian ini bertujuan untuk melakukan analisis curah hujan rencana pada Sub-DAS Ciherang, menganalisis debit banjir rencana dan besarnya limpasan, serta menganalisis upaya-upaya apa saja yang dapat dilakukan untuk mencegah terjadinya banjir. Pengukuran debit puncak dan limpasan dilakukan dengan analisis hidrologi dimana dalam pengukuran curah hujan rencana digunakan metode Log-Pearson III dan dalam pengukuran debit puncak digunakan metode hidrograf satuan sintesis Nakayasu. Sub-DAS Ciherang memiliki rata-rata curah hujan harian maksimum sebesar 103.18 mm/tahun dengan curah hujan rencana yang dihitung berdasarkan metode Log-Pearson III dengan periode ulang 2, 5, 10, 25, 50, dan 100 tahun sebesar 93.33, 124.11, 148.17, 182.99, 212.44, dan 245.02 mm. Sub-DAS Ciherang memiliki debit puncak dengan periode ulang yang sama yaitu sebesar 41.38, 55.03, 65.69, 81.13, 94.19, dan 108.63 m3/detik. Besarnya rasio DRO (direct runoff) dengan curah hujan pada 2 kejadian hujan sebesar 16.8% dan 19.3%. Besarnya DRO tersebut menyebabkan ancaman banjir pada daerah hilir cukup besar sehingga diperlukan upaya untuk mencegah terjadinya banjir. Upaya-upaya pencegahan banjir dapat dilakukan dengan konservasi tanah dan air yang dapat dibagi menjadi tiga metode, yaitu secara mekanik, vegetatif, dan kimiawi. Kata kunci : analisis hidrologi, , debit puncak, limpasan, pencegahan banjir, The Ciherang sub-watershed has land cover which is dominated by rice fields and plantations, namely 539.2 ha and 464.18 ha as well as high monthly rainfall from November to March. This study aims to analyze the planned rainfall in the Ciherang sub-watershed, analyze the planned flood discharge and runoff size, and analyze the efforts that can be made to prevent flooding. Measurement of peak discharge and runoff is carried out by hydrological analysis where the Log- Pearson III method is used in the planned rainfall measurement and the hydrograph method of the Nakayasu synthesis unit is used in the measurement of peak discharge. The Ciherang sub-watershed has a maximum daily average rainfall of 103.18 mm / year with a planned rainfall calculated based on the Log- Pearson III method with a return period of 2, 5, 10, 25, 50, and 100 years of 93.33, 124.11, 148.17, 182.99, 212.44, and 245.02 mm. The Ciherang sub-watershed has a peak discharge with the same return period, namely 41.38, 55.03, 65.69, 81.13, 94.19, and 108.63 m3/s. The magnitude of the DRO (direct runoff) ratio with rainfall in 2 rain events is 16.8% and 19.3%. The amount of DRO threatens the threat of flooding in the downstream area which is quite large so that efforts are needed to prevent flooding. Flood prevention efforts can be carried out by conserving soil and water which can be divided into three methods, namely mechanical, vegetative, and chemical. Keywords: flood preventing, hidrology analysis, peak discharge, runoff
Keyword: flood preventing, hidrology analysis, peak discharge, runoff

Judul: Analysis of Peak Discharge in the Cibaregbeg Sub-Watershed Sukabumi Regency
Abstrak: Sub-DAS Cibaregbeg didominasi oleh perkebunan teh yaitu sebesar 1231.35 ha dan curah hujan bulanan yang tinggi pada bulan Januari dan Februari, serta sebagian besar berada pada kemiringan lereng yang datar, sehingga sangat rawan terjadi banjir. Tujuan penelitian ini adalah melakukan analisis curah hujan rencana dan menganalisis debit puncak pada Sub-DAS Cibaregbeg. Sub-DAS Cibaregbeg memiliki curah hujan tahunan rata-rata sebesar 2549.88 mm/tahun dengan curah hujan rencana periode ulang 2, 5, 10, 25, dan 100 tahun sebesar 31.89, 32.42, 33.50, 37.00, 43.36, dan 57.71 mm. Sub-DAS Cibaregbeg memiliki debit puncak dengan periode ulang yang sama yaitu 182.18, 250.72, 392.76, 851.19, 1685.95, dan 3567.68 m3/detik. Pada periode ulang 10, 25, 50, dan 100 tahun menyebabkan ancaman banjir karena memiliki debit puncak yang lebih besar dari debit puncak rasional yaitu sebesar 378.75 m3/detik. Upaya untuk mencegah terjadinya banjir seperti mengubah tutupan lahan semak belukar dan tanah kosong menjadi tutupan lahan hutan atau mengolah tutupan lahan tegalan dengan sistem agroforestry. Sub-DAS Cibaregbeg memiliki rasio DRO (direct run-off) pada 3 kejadian hujan sebesar 1.29%, 1.51%, dan 2.14% menunjukkan besarnya jumlah hujan yang menjadi aliran langsung masih kecil. Kata kunci : analisis hidrologi, curah hujan, debit puncak, limpasan, The Cibaregbeg sub-watershed is dominated by tea plantations, namely 1231.35 ha as well as high monthly rainfall in January and February, and most of them are on a flat slope, so they are prone to flooding. The purpose of this study is to analyze the planned rainfall and analyze the peak discharge in the Cibaregbeg Sub-watershed. The Cibaregbeg sub-watershed has an average annual rainfall of 2549.88 mm/year with rainfall plans for return periods of 2, 5, 10, 25, and 100 years of 31.89, 32.42, 33.50, 37.00, 43.36, and 57.71 mm. The Cibaregbeg sub-watershed has peak discharge with the same return period, namely 182.18, 250.72, 392.76, 851.19, 1685.95, and 3567.68 m3/second. In the 10, 25, 50, and 100 year return periods the threat of flooding is caused because it has a peak discharge that is greater than the rational peak discharge, which is 378.75 m3/second. Efforts to prevent flooding include changing scrub and bare land cover to forest land cover or cultivating upland land cover using an agroforestry system. The Cibaregbeg sub-watershed has a DRO (direct run-off) ratio for 3 rain events is 1.29%, 1.51%, and 2.14%, indicating that the amount of rain that becomes direct flow is still small. Keywords : hydrological analysis, peak discharge, rainfall, runoff
Keyword: Hydrological analysis, Peak discharge, Rainfall, Runoff

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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