PEMETAAN ZONA BAHAYA SAND-RIFT DI PANTAI GLAGAH DAN SEKITARNYA, KECAMATAN TEMON DAN SEKITARNYA, KABUPATEN KULONPROGO

FAUZY HABIBIE AKHYAR, Dr. rer. nat. Doni Prakasa Eka Putra, S. T., M. T.

2018 | Skripsi | S1 TEKNIK GEOLOGI

New Yogyakarta International Airport (NYIA) merupakan salah satu proyek infrastruktur yang dipersiapkan untuk menghadapi perkembangan jumlah pengunjung di Yogyakarta. Lokasi proyek NYIA berada di atas satuan saturated dune fields yang berada di Desa Glagah, Temon, Kulon Progo. Kehadiran morfologi tersebut menjadi indikasi awal bahwa butir pasir dapat terangkut serta tergerakkan oleh angin. Maksud dari penelitian adalah menentukan zonasi potensi bahaya dari fenomena sand-drift. Tujuan yang ingin dicapai adalah mengetahui karakteristik gumuk pasir wilayah studi berdasarkan ukuran butir dan tingkat keaktifan gumuk pasir, mengetahui faktor yang mempengaruhi sand-drift serta mekanisme sand-drift, dan penentuan zona bahaya sand-drift berdasarkan korelasi data faktor penyebab sand-drift dan karakteristik gumuk pasir. Metode yang ditempuh adalah studi pra-lapangan meliputi analisis citra dan pustaka; pengambilan data lapangan meliputi pemetaan geologi, geomorfologi, tata guna lahan, pengukuran kedudukan ripple, pengambilan sample, dan pengukuran volume sedimentasi menggunakan sand-catcher; dilanjutkan dengan analisis laboratorium, meliputi analisis granulometri, diagram wind-rose, dan penentuan zona potensi sand-drift menggunakan Analytical Hierarchy Process (AHP). Hasil yang diperoleh: karakteristik gumuk pasir di wilayah studi adalah butir penyusun berukuran pasir sedang - pasir halus pada daerah pesisir, relatif menghalus semakin ke arah darat; endapan pasir juga memiliki sortasi baik, bersifat loose; terdapat dua satuan gumuk pasir, yakni satuan embryo dunes dan satuan fore dunes. Faktor berpengaruh dan mekanisme sand-drift: pola arah angin southeasterly, kecepatan angin berkisar 8,5 – 28 km/jam, dan sand-drift terpengaruh oleh tata guna lahan. Sedang, mekanisme sand-drift pada wilayah penelitian: 60% tertransport secara surface creeping dan rolling, 38% tertransport secara saltasi, dan 2% tertransport secara suspension. Berdasarkan ranking pembobotan kumulatif dari tiga, terdapat tiga zonasi potensi sand drift, yakni zona bahaya sand drift tinggi (63.91%), zona bahaya sand drift sedang (35.43%), dan zona bahaya sand drift rendah (0.66%).

The New Yogyakarta International Airport Project is one of the focuses of the Central Government in tackling the issue on the visitors’ demand-growth in Yogyakarta. The project itself is being built on a saturated sand-dune unit, located in Glagah Village, Temon, Kulon Progo. The presence of the mentioned geomorpholohic unit indicates that the sand-grains are movable by wind. The purpose of the research is to determine the potentially-hazardous zone due to the effect of sand-drift. The research aims to figure out the characteristics of the sand-dunes based on the grain-size domination and the type of sand-dunes based on the activity rate, to determine the factors that affect sand-drift and its drifting mechanisms, and to determine the potentially hazardous zones based on the correlation of causing factors and its characteristics. The research was conducted through several phases, namely pre-field image analysis and literature studies; field-data acquisition which include geologic, geomorphologic, and land-use mapping, ripple direction measurement, sand-sample collection, and the quantification of sedimentation volume using a sand-catcher; followed by the laboratory analysis, which include granulometry and wind-rose diagram analysis, and the sand-drift zones are determined by Analytical Hierarchy Process (AHP). The findings of the study are: the characteristics of sand-dunes is the grain is dominated by medium – fine sand on the shoreline, and relatively fining towards the land; the sand deposit is well-sorted, loose; there are two sand-dune units, which are embryo dunes and fore dunes. The factors and mechanism of sand drift are as follow: the dominant wind-pattern is southeasterly, the wind speed range from 8.5 – 28 km/h, and the sand-drift phenomenon is highly influenced by the land-use. Meanwhile, the mechanism of sand-drift are as followed: 60% of sand-grains are transported by surface creep and rolling, 38% through saltation, and 2% through suspension. Based on the cumulative ranks, the zones can be divided into three, namely high hazardous zone, medium hazardous zone, and low hazardous zone.

Kata Kunci : sand-drift, sand-dunes, NYIA, transportasi sedimen