Analysis of Debris Flow Hazard in Volcanic Soil by the Flood Flows Modelling (DFLOWZ) and Nakayasu Synthetic Unit Hydrograph

Abstract

The Mount Batur Geopark area is vulnerable to debris flow triggered by heavy rainfall and weathered rocks that threaten the villages below. The estimation of the potential debris flow inundated area in this study has been determined by using the DFLOWZ model. The Digital Elevation Model (DEM) is the primary requirement data input in the model. Furthermore, the analysis of mean rainfall intensity and the hydrograph flood design have been calculated by the polygon Theissen and Nakayasu synthetic unit hydrograph method, respectively. The observation result has exhibited that basin flow occurs in the valley and river at the elevation ± 1500 m above sea level, which curves in hilly valleys and westward flow direction. The DFLOWZ analysis result depicts the area potentially inundated by a debris flow event as 49,830 m 2 with an inundation height based on the slope of 5-7 m. Furthermore, the peak of discharge debris flow, the debris flow volume, and the debris flow range are 100.15 m 3 /s, 50,072.85 m 3 , and 49.5 meters, respectively. This condition indicates that there is a risk of debris flow in the form of sand, silt, and boulders around the river in the range of 49.5 meters and a sediment thickness of 1-1.5 meters.

Analisis Reability Pengaruh Vegetasi Rumput Gajah Dengan Metode Elemen Hingga Pada Lereng Tanah Vulkanik

“…Berdasarkan penyelidikan lapangan terdapat morfologi wilayah dan jenis tanaha serta peta pergerakan tanah sebenarnya wilayah kaldera Gunung Batur tersusun oleh batuan vulkanik yang telah lapuk, sehingga menjadi tanah vulkanik. Desa-desa sekitar Kaldera Gunung Batur khususnya sekitar Desa Buahan, Dusun Dukuh Abang Batudinding, Dusun Cemara landung dan Dusun Terunyan, yang terbentuk secara alami berada pada lereng Gunung Abang (gunung berapi parasit) dan Bukit Terunyan sangat rawan mengalami longsor bahan rombakan (Debris Flow) akibat bukit disekitarnya yang minim vegetasi (I. Nengah Sinarta et al, 2020) (I. Nengah Sinarta et al, 2023.…”

Modelling the possible Debris Flow events in Swat Mountains Using Flow-R -A Case Study in Pakistan

“…In conclusion, the combination of advanced modelling techniques, precise observation, and detailed analysis has contributed signi cantly to the overall comprehension of the debris ow risk in the Mount Batur Geopark region. (Sinarta et al, 2023) R.ava ow stands as an indispensable software tool specially crafted to simulate and analyse debris ows, those swift and immensely destructive mass movements comprising water, sediment, and debris hurtling down steep slopes. Findings showed that r.ava ow generally demonstrated the ability to reasonably replicate the spatial and temporal evolution of ow heights, velocities, travel times, and volumes for these complex mass ow events.…”

Safety Factor and Settlement Analysis of Borepile Foundation in Warmadewa Gianyar Hospital Building

“…Unlike the case with granular soil at the planning location of the Warmadewa Hospital building, which is designed on granular soil, which is predominantly sand, of course, it has a different safety factor value depending on the soil [16], [17] property data. Further analysis is needed to optimize the planning design results because using only the Mayerhoof method is not optimal because the study focuses only on similar soil conditions [18]- [20].…”