Planning tsunami vertical evacuation routes using high-resolution UAV digital elevation model: case study in Drini Coastal Area, Java, Indonesia

Abstract

Tsunami evacuation is a short process that must be carried out in minutes. Determining the evacuation routes and safe areas is equally important in tsunami evacuation planning. It can be established from least cost distance (LCD) anisotropic model. We use the coastal of Drini, Gunungkidul, Java, Indonesia, as the study area, which is located in a tropical coastal karst region, with a typical karst cone formation. The topographic condition of the karst cone could be an ideal location for tsunami vertical evacuation (TVE). High-resolution orthomosaic images and digital elevation model (DEM) generated from the structure from motion (SfM) process were used as the main data. The tsunami inundation model was calculated based on neighboring operations using raster calculator from the elevation value in the DEM. Land cover identification from high-scale orthomosaic images showed the variation in speed conservation values (SCVs). The slope value was also used as a surface cost that will affect the travel time to the TVE shelters. The results of the model show that TVE is the main alternative in tsunami evacuation planning beside horizontal evacuation. They provide an evaluation of the location of the assembly points and evacuation routes provided by the government, which have been considered ineffective because of the inappropriate model. The results of the study provide an overview of determining the evacuation routes and shelters. Optimum locations can minimize travel time, provide adequate capacity, and be safe from inundation.

Geomorfologi Tanah Pada Transisi Geologi Formasi Wonosari dan Nglanggran di Kecamatan Purwosari Gunungkidul Yogyakarta

“…TIN UAV dapat mengambarkan geomorfologi detail pada skala 1:10.000 sampai dengan 1:5.000. Hasil yang detail, tegas, dan halus juga diperoleh dari TIN UAV pada kajian pemodelan tsunami detail (Marfai et al, 2021;Fatchurohman et al, 2022) dan pada identifikasi longsor detail (Samodra et al, 2018;Samodra et al, 2020). Hasil TIN UAV kemudian didetailkan dari pengamatan lapangan berupa singkapan batuan.…”

Evaluasi Pemodelan Jalur Evakuasi Tsunami Wilayah Kepesisiran Pantai Krakal dan Pantai Slili Gunungkidul

“…Pemilihan jalur evakuasi akan mempengaruhi tingkat angka kematian secara signifikan, sehingga penentuan jalur perlu memperhatikan jarak dan waktu (Takabatake et al, 2020). Penentuan jalur evakuasi pada wilayah kepesisiran Gunungkidul pernah dilakukan oleh Marfai et al, 2021, penentuan jalur evakuasi menggunakan citra skala resolusi tinggi dengan memberikan rekomendasi evakuasi vertikal yaitu memilih beberapa alternatif jalur menuju bukit. Pada penelitian sebelumnya focus mencari jalur alternatif sedangkan penelitian yang membandingkan 2 cara seperti Network Analysis dan LCD dalam suatu wilayah kajian yang memiliki karakteristik morfologi berbeda belum banyak diteliti.…”

“…Semakin landai lereng maka kecepatan seseorang berjalan semakin cepat dan sebaliknya, yang dirumuskan dalam persamaan Marfai et al (2021) lihat Gambar 2.…”

“…Lokasi Penelitian Gambar 2. Grafik Speed Conservation Value (SCV) sesuai Tobbler's Hiking Function (Marfai et al, 2021) vektor atas jarak yang mengacu pada jaringan (network) (Purbani et al, 2015). Network analysis berbasis data vektor, dengan model yang digunakan yaitu New Route Analysis.…”

Coastal hazards mapping using high-resolution UAV image and DEM. A Case study in Siung Beach, Gunungkidul, Indonesia

“…The inundated model mainly affects the relatively flat terrain occupied by houses, food stalls, motels, and parking areas. Therefore, vertical tsunami evacuation is recommended to be performed in this topographical condition [21]. The primary purpose of tsunami vertical evacuation is to save lives, placing the affected community to higher ground and evacuating to safe places afterward [22].…”