Definitions and Concepts for Quantitative Rockfall Hazard and Risk Analysis

There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests using terms that appear to be the most logic and explicit as possible and describes methods to derive some of the main hazards and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized and diffuse hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed, and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the reach probability, and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (passage frequency) can be derived. This frequency is relevant for risk assessment when the element at risk can be damaged several times. If it is not replaced, the probability that it is impacted by at least one rockfall is more relevant.

Definitions and Concepts for Quantitative Rockfall Hazard and Risk Analysis

There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests to use terms that appear to be the more logic and explicit as possible, and describes methods to derive some of the main hazard and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized hazards and diffused hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the propagation probability and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (reach frequency) can be derived. However, when the element at risk is not replaced or repaired, the probability that it is impacted by at least one rockfall must be considered.

GIS-Based Quantitative Landslide Risk Assessment Approach for Property and Life at Bartin Hepler

In Turkey, landslides are the second most common natural disasters that cause damages in Turkey that follow the earthquakes. Thus, landslide risk assessment is of crucial importance in this area. Therefore in this study a quantitative approach for mapping landslide risk is developed for property and life at local scale. The approach is first based on the identification of existing elements at risk in the area by the developed algorithm. Then the vulnerability approach focuses on determination of quantitative vulnerability values for each element at risk by considering temporal and spatial impacts by adopting a “damage probability matrix“ approach. The loss estimation was combined with the hazard values which are based on former work done in Bartın Kumluca area where a detailed study of landslide occurrence and hazard in the recent past (last 30 years) was carried out. The final result risk maps for property ($/pixel/year) and life (life/pixel/year) shows all losses per pixel annually for each element at risk in Hepler village.

Aplikasi SIG Untuk Pemetaan Zona Tingkat Bahaya Dan Keterpaparan Pemukiman Terhadap Tsunami Kota Denpasar

Denpasar adalah ibukota provinsi Bali termasuk dalam wilayah terindikasi rawan tsunami karena berada didekat pinggir pantai serta memiliki ketinggian dan kemiringan yang relative kecil kepermukaan laut. Pemukiman merupakan aset wilayah yang harus dijaga. Sehingga zona keterpaparan pemukiman terhadap bahaya tsunami dibutuhkan guna memberikan informasi pada penduduk yang tinggal di kota tersebut. Tingkatan keterpaparan dilihat berdasarkan hazard dan element at risk. hazard ini dilihat berdasarkan jarakdari garis pantai, ketinggian, jarak dari sungai, dan juga kemiringan lereng dari daerah Denpasar ini, sedangkan Element at risk atau elemen yang terkena bencana tsunami nya ialah pemukiman. Pemetaan menggunakan teknik overlay, metode skoring dan pembobotan menggunakan software ArcMap 10.3 sebagai pendekatan berbasis Sistem Informasi Geografis (SIG). Hasil penelitian menunjukan bahaya didominasi tingkat sedang dan tinggi. tingkat keterpaparan tsunami pada pemukiman di kota Denpasar ini didominasi oleh tingkat keterpaparan sedang hingga tinggi dengan luas 3,46 km2 atau 27,21% dari luas Kota Denpasar dan terpusat di Kec. Denpasar Timur (25,14 km2) dan Kec. Denpasar Barat (15,02 km2). Selain itu, pemukiman dengan keterpaparan tinggi yakni di Kec. Denpasar Selatan dengan luas 16,80 km2. Dikarenakan wilayah ketinggian yang rendah dan jarak dengan pantai dekat.

LANDSLIDE VULNERABILITY ASSESMENT (LVAs) IN LUYANG AREA, KOTA KINABALU, SABAH, MALAYSIA

Landslide issues in Malaysia is successfully attract the interest and attention of stakeholders and the community of scientists to reduce the risk. Landslides are influenced by many factors that range from the intensity, duration and extent of a triggering factor (e.g. earthquake and rainfall) to the local physical conditions such as landform, morphological, geological materials and structures, hydrological and land uses. In this paper, we present the results of the Landslide Vulnerability Assessment (LVAs). Vulnerability is defined as the degree of losses of a given element at risk of being exposed to the occurrence of a landslides of a given magnitude or intensity, and often expressed on a scale of 0 (no loss) to 1 (total loss). The selection of the best LVAs depends on the exposed elements, landslide types and the scale of analysis. The concept of LVAs also refers to the feasibility of elements at risks on engineering structures, infrastructure facilities, communication systems, commercial (including insurance disclosures) and social. The vulnerability parameters include in assessing LVAs in this study are 1) physical implication (building structures, internal materials, property damage, infrastructural facilities and stabilization actions), social status (injury, fatalities, safety, loss of accommodation and public awareness) and interference on environment (affected period, daily operation & diversity). LVAs for study area produced by combining or overlaid of all Physical Vulnerability (Vp), Social Vulnerability (Vs) and Environmental Vulnerability (Ve) maps. The results for the Total of LVAs indicates that 30% (0.90 sq.m) of the study area classified as Very Low, 8% (0.24 sq.m) as Low, 8% (0.24 sq.m) as Moderate, 28% (0.84 sq.m) as High, 8% (0.24 sq.m) as Very High and 18% (0.54 sq.m) as Extremely High. Landslide Vulnerability level at a “high” to “very high” degree can leave an impact on individuals and society. This study found that residential, commercial, public and industrial infrastructure has higher vulnerability rather than the agricultural and forestry areas. This LVAs approach is suitable as a guideline for preliminary development planning, control and manage the landslide hazard / risk in the study area and potentially to be extended with different background environments.

Back-analysis of rockfalls for the definition of an empirical vulnerability function for buildings

<p>The vulnerability of buildings to the impact of rockfalls is a key component of Quantitative Risk Assessment for rockfall phenomena. Only a few attempts to quantitatively assess vulnerability have been presented in the literature due to the lack of high-quality rockfall and damage data. For processes such as debris flows, snow avalanches or earthquakes, well-established methods for the estimation of physical vulnerability are already available.</p><p>The present work aims to develop an empirical rockfall vulnerability function by coupling rockfall back-analysis modelling of several damaging events occurred in different lithological and geomorphological settings. A sound database of damage to specific categories of structures impacted by rockfalls is build up by archive research of historical events and high-quality field observations of recent events. Damages are classified according to four damage types: superficial (degree of loss: 0.1-0.2) to structural (degree of loss: 1.0). The back-analysis of rockfalls and the interaction with element at risk is performed with the 3D numerical model Hy- STONE. The code uses a hybrid modelling approach and random sampling of input parameters from different probability density distributions (uniform, normal, exponential) to account for the complexity of the rockfall process and influencing factors. The elements at risk are integrated as lines to the model, impact points being able to be displayed and extracted as point vector data. This enables a precise analysis of simulated energies and observed damage for each building impacted in the past to define an empirical vulnerability function. The empirical vulnerability function is established by fitting damage-energy data through a sigmoidal function. This empirical vulnerability function for buildings is fundamental to compute the expected degree of loss for each element of risk, especially in areas where no detailed rockfall or damage data is available.</p>

Simulation of fragmental rockfalls detected using terrestrial laser scans from rock slopes in south-central British Columbia, Canada

Rockfall presents an ongoing challenge to the safe operation of transportation infrastructure, creating hazardous conditions which can result in damage to roads and railways, as well as loss of life. Rockfall risk assessment frameworks often involve the determination of rockfall runout in an attempt to understand the likelihood that rockfall debris will reach an element at risk. Rockfall modelling programs which simulate the trajectory of rockfall material are one method commonly used to assess potential runout. This study aims to demonstrate the effectiveness of a rockfall simulation prototype which uses the Unity 3D game engine. The technique is capable of simulating rockfall events comprised of many mobile fragments, a limitation of many industry standard rockfall modelling programs. Five fragmental rockfalls were simulated using the technique, with slope and rockfall geometries constructed from high-resolution terrestrial laser scans. Simulated change detection was produced for each of the events and compared to the actual change detection results for each rockfall as a basis for testing model performance. In each case the simulated change detection results aligned well with the actual observed change in terms of location and magnitude. An example of how the technique could be used to support the design of rockfall catchment ditches is shown. Suggestions are made for future development of the simulation technique with a focus on better informing simulated rockfall fragment size and the timing of fragmentation.

PENERAPAN FUZZY LOGIC DALAM PEMBUATAN PETA ELEMENT AT RISK BENCANA LUAPAN BANJIR SANGAI AIR BENGKULU KOTA BENGKULU

Banjir merupakan suatu bencana yang dapat menimbulkan kerugian dan kerusakan di berbagai bidang, khususnya infrastruktur. Salah satu upaya untuk mencegah dan mengurangi dampak dari bencana banjir yaitu dengan pembuatan simulasi melalui pemodelan spasial dalam bentuk peta element at risk. Pada pembuatan peta element at risk, input data berupa peta yang diunduh dari Open Street Map yang berisikan kenampakan alam maupun infrastruktur dari simulasi bencana yang dibuat menggunakan logika Fuzzy. Penerapan logika Fuzzy digunakan untuk menginterpretasikan statemen yang samar dari persentase area bangunan yang terdampak pada setiap klasifikasi area luapan banjir menjadi sebuah pengertian yang logis dalam pengklasifikasian kerusakan “Berat’, “Sedang” dan “Ringan”. Berdasarkan hasil simulasi bencana banjir yang telah dilakukan, didapati bahwa jumlah bangunan yang terkena dampak bencana banjir luapan Sungai Air Bengkulu adalah sebanyak 37 bangunan “Rusak Berat’, 216 “Rusak Sedang’ dan 329 “Rusak Ringan’, dengan jumlah korban jiwa terdampak sebanyak 2.328 jiwa.

PEMETAAN KERENTANAN LAHAN SAWAH DI KABUPATEN KARAWANG

Musim hujan dengan intensitas yang tinggi dapat menyebabkan terjadinya banjir. Banjir sebagai salah satu fenomena perubahan iklim yang dapat mengancam kawasan pertanian dan dapat mengakibatkan gagal panen, menurunkan mutu hasil, terganggunya produksi serta penurunan pendapatan petani. Bentuk lahan memiliki peran penting dalam penelitian banjir, karena bentuk lahan merupakan salah satu area dimana proses mengalirnya air hujan menuju ke laut. Kejadian banjir menimbulkan kerentanan yaitu suatu keadaan penurunan ketahanan akibat pengaruh banjir yang mengancam kehidupan, mata pencaharian, sumber daya alam, infrastruktur, produktivitas ekonomi, dan kesejahteraan. Tujuan penelitian ini adalah melakukan pemetaan kerentanan fisik lahan dan kerentanan sosial ekonomi petani terhadap kejadian banjir. Kerentanan fisik lahan menggambarkan tingkat kerusakan yang timbul bila terjadi banjir, dan dampak yang ditimbulkan terhadap keluarga petani dinyatakan sebagai kerentanan sosial ekonomi. Penentuan kerentanan dengan metode skoring dan pembobotan terkait penggunaan lahan, ketinggian topografi, jarak dari sungai serta dampak sosial ekonomi terhadap petani. Wilayah yang memiliki kerentanan tinggi dapat mengakibatkan elemen risiko (element at risk) untuk terpapar bahaya menjadi semakin besar dan dapat meningkatkan risiko bencana.