MODEL KERENTANAN GERAKAN TANAH WILAYAH KABUPATEN SUKABUMI SECARA SPASIAL DAN TEMPORAL

Khori Sugianti, Sukristiyanti Sukristiyanti, Adrin Tohari

Abstract


Spatial and temporal prediction of landslide hazard is required for hazard mitigation. This paper aims to present the results of areal slope stability modeling in Sukabumi Regency, considering the spatial characteristics of the slope and soil properties and temporal variation of rainfall. The modeling uses TRIGRS software to calculate the grid based slope safety factor with a size of 100 m x 100 m due to the infiltration of rainwater. Results of modeling show that landslide vulnerability of Sukabumi Regency is significantly influenced by topography and soil engineering characteristics. Meanwhile, the variation of rainfall intensity is the causative factor of temporal variation of landslide vulnerability. Based on the safety factor-based zonation, high vulnerability zone is  located in the District of Pelabuhan Ratu, Cikidang, Cisolok, Kabandungan, Parakan Salak, Nagrak, Cibadak, Gegerbitung, Nyalindung, Ciracap and Warung Kiara. Many previous landslides occurred in this susceptibity zone. Thus, this landslide susceptibility modelling may apply to a spatial mapping and temporal prediction of landslide hazard.

Prediksi bahaya gerakan tanah secara spasial dan temporal diperlukan untuk mitigasi bencana gerakan tanah. Makalah ini bertujuan untuk menyajikan hasil pemodelan tingkat kerentanan gerakan tanah dengan mempertimbangkan karakteristik lereng dan kekuatan tanah secara spasial dan curah hujan harian secara temporal di wilayah Kabupaten Sukabumi. Pemodelan menggunakan perangkat lunak TRIGRS untuk menghitung faktor keamanan lereng berbasis grid dengan ukuran 100 m x 100 m akibat infiltrasi air hujan. Hasil pemodelan menunjukkan tingkat kerentanan gerakan tanah spasial di Kabupaten Sukabumi dipengaruhi oleh topografi dan karakteristik keteknikan tanah. Sementara itu, curah hujan kumulatif menjadi faktor pengontrol penyebab perubahan tingkat kerentanan gerakan tanah temporal. Berdasarkan nilai faktor keamanan lereng, daerah dengan kerentanan gerakan tanah tinggi tersebar di Kecamatan Pelabuhan Ratu, Cikidang, Cisolok, Kabandungan, Parakan Salak, Nagrak, Cibadak, Gegerbitung, Nyalindung, Ciracap, dan Warung Kiara. Tingkat kerentanan ini bersesuaian dengan lokasi-lokasi gerakan tanah yang terjadi di daerah-daerah tersebut. Dengan demikian, pemodelan kerentanan gerakan tanah ini dapat digunakan untuk membantu dalam memprediksi gerakan tanah secara spasial dan temporal.



Keywords


safety factor, landslide, rainfall infiltration, susceptibility modeling.

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DOI: http://dx.doi.org/10.14203/risetgeotam2016.v26.270

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