Kajian Fisik Lingkungan Geologi Untuk Pengembangan Kawasan Pantai Utara Di Kabupaten/Kota Cirebon Jawa Barat

Abstract

Data yang digunakan untuk kajian ini adalah : kecepatan sedimentasi, daya dukung tanah, dan analisis besar butir. Kecepatan sedimentasi secara vertikal berkisar antara 1.023 sampai 3.835 cm/tahun dan pertumbuhan pantai dari tahun 1999 hingga tahun 2000 adalah 7,287 cm. Volume sedimen yang terendapkan selama tiga tahun adalah 266.621.000 m2 x 0,07287 meter = 19.428.672,27 m3. 
 Daya dukung tanah diketahui dari hasil uji Standart Penetration Test (SPT) dari 0 m hingga kedalaman 24,45 m memiliki kepadatannya relatif agak kaku (stiff) yang merupakan endapan pantai. Kedalaman 24,00 sampai 41,00 meter memiliki kepadatannya relatif sangat kaku (very stiff) hingga keras (hard). Dari nilai indeks plastisitasnya dapat dikatakan bahwa semua jenis tanah lempung (CH) di daerah penelitian memiliki sifat plastisitas tinggi dan kohesif. 
 Hasil analisis besar butir menunjukkan bahwa secara umum jenis tanah/sedimen di daerah penelitian terdiri dari sedimen yang memiliki fraksi halus berupa persentasi pasir sangat halus terbesar kemudian fraksi lanau. Berdasarkan uji konsolidasi dari contoh pemboran memperlihatkan pada tanah/sedimen di daerah penelitian yang berfraksi halus memiliki tingkat kompresibilitas tanah sedang hingga tinggi.
 
 Kata kunci : kecepatan sedimentasi, standard penetration test, besar butir, Cirebon
 
 
 Data used for this study are sedimentation rate, soil bearing capacity, and grain size analysis.
 Rate of sedimentation in vertical is among 1.023 to 3.835 cm/year and beach growth from years 1999 until year 2000 about 7,287 cm. Sediment are deposited to reach volume up to three year about 266.621.000 m 2 x 0,07287 m = 19.428.672,27 m 3 . 
 Bearing capacity of soil from Standard Penetration Test (SPT) to the depth of 24,45 meters shows a stiff densities and constitute of beach sediment. From the depth of 24,00 to 41,00 meters shows densities a very stiff until hard densities. Their plasticity index of all clay in the study area are hingh plasticity (CH) and cohesive. 
 From the grainsize analysis shows that all the soil/sediments in the study area are fine sediment which are very fine sand and silt. The fine sand are more dominant than the silt. Based on consolidation test from drilling samples those are also soil/sediments of fine fraction show a compressibility value from medium to high.
 
 Keywords: sedimentation rate, standard penetration test, grain size, Cirebon

Geochemical of Karst Water in the Western part of Gunungkidul District Area

“…Based on Yogyakarta's regional geological map, the study area comprises the Wonosari Formation [2]. This formation is composed of reef limestone, calcarenite, and tuffaceous limestone.…”

“…The study area is in the western part of the Southern Mountains physiographic zone [1], specifically the Gunungsewu sub-zone. Panggang and surrounding areas are part of the karst region [2], famous as the Gunungsewu Karst Landscape Area. In general, the karst zone has its peculiarities, especially in terms of water resources [3].…”