Liquefaction potential of Quaternary alluvium in Bolu settlement area,Turkey

Groundwater bearing alluvial units in the seismically active settlement areas may bring out probable damage on the urban and built environment due to liquefaction. Bolu settlement area and surroundings are located in the North Anatolian Fault Zone. Geotechnical boreholes were drilled in order to determine the distribution of the geological units, to obtain representative soil samples and to measure groundwater level. Quaternary aged alluvium is the main geological unit in the South of study area. Stiffness and consistency of the soils were determined by Standart penetration test. P and S wave velocities of soil have been measured along the seismic profiles. The index and physical properties of the samples have also been tested in the laboratory. Liquefaction potential and safety factor of the sandy levels in Quaternary aged alluvium were investigated by different methods based on SPT and V _s. Liquefaction seems to be a significant risk in case of an earthquake with a _max = 0.48 g and M _w = 7.5 at different levels of the boreholes. This situation may bring out environmental problems in the future.     

Estimation of soil erosion using RUSLE in a GIS framework: a case study in the Buyukcekmece Lake watershed,northwest Turkey

This study was aimed at predicting soil erosion risk in the Buyukcekmece Lake watershed located in the western part of Istanbul, Turkey, by using Revised Universal Soil Loss Equation (RUSLE) model in a GIS framework. The factors used in RUSLE were computed by using different data obtained or produced from meteorological station, soil surveys, topographic maps, and satellite images. The RUSLE factors were represented by raster layers in a GIS environment and then multiplied together to estimate the soil erosion rate in the study area using spatial analyst tool of ArcGIS 9.3. In the study, soil loss rate below 1 t/ha/year was defined as low erosion, while those >10 t/ha/year were defined as severe erosion. The values between low and severe erosion were further classified as slight, moderate, and high erosion areas. The study provided a reliable prediction of soil erosion rates and delineation of erosion-prone areas within the watershed. As the study revealed, soil erosion risk is low in more than half of the study area (54%) with soil loss <1 t/ha/year. Around one-fifth of the study area (19%) has slight erosion risk with values between 1 and 3 t/ha/year. Only 11% of the study area was found to be under high erosion risk with soil loss between 5 and 10 t/ha/year. The severe erosion risk is seen only in 5% of the study area with soil loss more than 10 t/ha/year. As the study revealed, nearly half of the Buyukcekmece Lake watershed requires implementation of effective soil conservation measures to reduce soil erosion risk.     

Spatial analysis of morphometric indices: the case of Bolu pull-apart basin,western section of North Anatolian Fault System,Turkey

Advances in quality, acquisition and processing of high-resolution digital topography over the past decade have enabled geomorphologists to interpret topography in terms of tectonic processes in a quantitative and more objective way. This study defines the tectonic impact of the North Anatolian fault system (NAFS) on the evaluation and activity of the Bolu pull-apart basin using morphometric indices based on topographic maps. In this study, three different indices including valley floor width to height ratio (Vf), asymmetry factor (Af), and Stream Length Gradient Index (SL) are applied to the tectonic basin area. To detect the deviation from spatial randomness of applied indices, the weighted correlation coefficient Moran’s I is used, and results are interpreted at 99% confidence interval. According to the results, the tectonic impact of NAFS on the northern and western sides of the basin distinctly differs from one another. Clustered distribution of Vf and Af values on the southern side of the basin margin reveals that this side of the basin margin is tectonically more deformed compared with the northern side. The applied methodology reveals that the spatial analysis of the morphometric indices proved to be the effective tool in analyzing tectonic influence of the fault system on the opposite side of the basin margins.     

Typhoon disaster in China: prediction,prevention, and mitigation

Typhoon-induced disaster is one of the most important factors influencing the economic development and more than 250 million in China. In view of the existing state of typhoon disaster prediction, prevention, and mitigation, this paper proposes a new probability model, Multivariate Compound Extreme Value Distribution (MCEVD), to predict typhoon-induced extreme disaster events. This model establishes prevention criteria for coastal areas, offshore structures, and estuarine cities, and provides an appropriate mitigation scheme for disaster risk management and decision-making.     

Resource allocation for regional earthquake risk mitigation: a case study of Tehran,Iran

This paper presents a new optimization model to help cities in seismically active developing countries decide (1) How much to spend on pre-earthquake mitigation versus waiting until after an event and paying for reconstruction or simply not rebuilding damaged buildings? (2) Which buildings to mitigate and how? and (3) Which buildings to reconstruct and how? It extends previously developed optimization models to consider the particular issues that arise in such countries. First, the model allows for the possibility that some damaged buildings will not be reconstructed immediately and keeps track of any lost building inventory. Second, buildings can be mitigated to, or when damaged, reconstructed to, any appropriate structural type and seismic design level. Finally, the model objectives include minimizing the chance of an extremely high death toll in any one earthquake and minimizing the average annual death toll across earthquakes. The model is illustrated through a case study analysis for Tehran, Iran.     

A generic decision model for developing concentrated rural settlement in post-disaster reconstruction: a China study

The increasing impacts of natural disasters on disadvantaged rural areas, especially in developing countries, have led to concerns regarding post-disaster rural settlement reconstruction. Various approaches, including resettlement and in-situ reconstruction, have been adopted, both of which disregard changing the pattern of dispersed settlement in villages. Against a pattern of dispersed settlement, developing a concentrated rural settlement (CRS) within a village is argued to enable the resilience of rural villages and provide a basis for sustainable development after a disaster. Nevertheless, this has received little attention when determining a plan of actions for post-disaster reconstruction. No specific guidelines can be referenced when developing CRS in post-disaster reconstruction due to the lack of a generic decision model. Therefore, this study examines the process of developing CRS in post-disaster reconstruction by mapping four cases selected in Dujiangyan, China, after the 5.12 Sichuan Earthquake in 2008. The examination leads to establishing a generic decision model for developing CRS in post-disaster reconstruction, which incorporates all the proficiencies embodied in the existing practices. This model provides an alternative tool for planning CRS in post-disaster reconstruction. It can also serve as a vehicle for identifying both effective practices and weak areas by comparing varying cases.     

Flood prediction and mitigation in coastal tourism areas,a case study: Hurghada,Egypt

Flood mitigation involves the management and control of floodwater movement, such as redirecting flood runoff through the use of floodwalls and flood gates, rather than trying to prevent floods altogether. The prevention and mitigation of flooding can be studied on three levels: on individual properties, small communities, and whole towns or cities. The current study area is located in Hurghada on the Red Sea, which is considered an important area for coastal tourism. The study area is located at distance 7.50 km from El Gouna city along the Red Sea and east of Hurghada–Al Ismaileya road. The aim of this research is to derive the runoff flow paths across the study area and their flow magnitudes under different rainfall events of 10, 25, 50, and 100 year return periods in order to design the flood mitigation measures to protect such important areas. Field data (e.g., topographic data and rainfall intensities) were collected for the study area. The results indicated that the site is exposed to high flash flood risk and protection work is required. In order to protect the area from flood risks, locations of number of drainage channels and dams were selected and designed based on flood quantity and direction. The proposed mitigation system is capable of protecting this crucial area from flood risks and increases the national income from tourism. This study can be applied in different areas of Egypt and the world.     

基于RS和GIS的地质灾害易发性定量评价:以湖北省五峰县为例

根据地质灾害的群发性和区域性的特点,运用地质统计学理论,通过分析,选取研究区内致灾因子,采用信息量模型进行地质灾害易发性定量评价。文中采用地质统计学信息量法,以GIS技术和RS技术为基础,从致灾机理上对各致灾因子进行选取和分析,使用GIS空间分析技术,完成了地质灾害易发性分区定量分析。分析结果表明,研究区内:(1)软硬相间碳酸盐岩类、(2)与河谷距离50～350m的斜坡带、(3)软硬相间碎屑岩类、(4)公路两侧1km范围、(5)斜坡在断裂带影响范围以内(1km)、(6)与河谷距离<50m或350～550m等6大影响因子对地质灾害的发生起主导作用。其中,除"公路两侧1km范围"为人类工程活动外,其他因素均为地质动力作用。研究完成的五峰县地质灾害易发分区定量评价,为五峰县的经济发展和城镇规划提供了科学依据,同时为以后在鄂西南地区进行地质灾害遥感解译提供了参考。     

Seismic risk assessment of buildings in urban areas: a case study for Denizli,Turkey

This study aims to carry out a seismic risk assessment for a typical mid-size city based on building inventory from a field study. Contributions were made to existing loss estimation methods for buildings. In particular, a procedure was introduced to estimate the seismic quality of buildings using a scoring scheme for the effective parameters in seismic behavior. Denizli, a typical mid-size city in Turkey, was used as a case study. The building inventory was conducted by trained observers in a selected region of Denizli that had the potential to be damaged from expected future earthquakes according to geological and geotechnical studies. Parameters that are known to have some effect on the seismic performance of the buildings during past earthquakes were collected during the inventory studies. The inventory includes data of about 3,466 buildings on 4,226 parcels. The evaluation of inventory data provided information about the distribution of building stock according to structural system, construction year, and vertical and plan irregularities. The inventory data and the proposed procedure were used to assess the building damage, and to determine casualty and shelter needs during the M6.3 and 7.0 scenario earthquakes, representing the most probable and maximum earthquakes in Denizli, respectively. The damage assessment and loss studies showed that significant casualties and economic losses can be expected in future earthquakes. Seismic risk assessment of reinforced concrete buildings also revealed the priorities among building groups. The vulnerability in decreasing order is: (1) buildings with 6 or more stories, (2) pre-1975 constructed buildings, and (3) buildings with 3–5 stories. The future studies for evaluating and reducing seismic risk for buildings should follow this priority order. All data of inventory, damage, and loss estimates were assembled in a Geographical Information System (GIS) database.     

High‐resolution remote sensing and GIS techniques for geobase data supporting archaeological surveys: A case study of ancient Doliche,southeast Turkey

The detection, surveying, and analysis of ancient settlement structures using remote sensing techniques offer a unique opportunity to quickly map the locations of archaeological objects in a relatively short time. High‐resolution images contribute information to the documentation and spatial relation of these objects, especially if Geographic Information Systems (GIS) and Web‐based applications are used. The aim of this study was to assess the potential use of satellite data and aerial imagesacquired by a remote‐controlled balloon to generate geospatial data with a range of resolutions and information depths. The study area was Doliche, in the landscape of ancient Commagene (Turkey), where conventional flight campaigns are impossible or strongly restricted. Recently generated data sets (i.e., topographic maps, ortho‐images, terrain models) were combined with field observations to derive ancient and modern landscape patterns and their possible relation to an assumed “ancient procession road” between the village Doliche (Dülük) and the nearby sanctuary of theRoman divinity Iupiter Dolichenus. © 2010 Wiley Periodicals, Inc.     

Practices in disaster mitigation in the case of the 2015 Typhoon Koppu debris flows in Nueva Ecija,Philippines

Natural Hazards - In October 2015, heavy rains brought by Typhoon Koppu generated landslides and debris flows in the municipalities of Bongabon, Laur, and Gabaldon in Nueva Ecija province....     

Multi-agent-based data exchange platform for bridge disaster prevention: a case study in Taiwan

Geographic location and natural environment expose Taiwan to an elevated risk of natural disasters that severely damage human life and national infrastructure. Currently, disaster information is handled through distributed systems maintained by different management agencies. Gleaning critical information from disparate Web sites is a difficult and labor-intensive task that makes consolidating disaster information impractical. Lack of such integration delays alerts notification from being disseminated to relevant administrative agencies in a timely manner, stalling necessary decision making and magnifying the disaster. This research developed a data exchange platform to integrate and exchange data between distributed systems using software agent techniques. Such techniques were designed to exchange data automatically. Agents become active at the onset of a disaster event and compile data from various resources to report on the current state of bridges. Also, action recommendations delivered by the system can assist bridge managers make appropriate decisions.     

Assessment of aquifer vulnerability based on GIS and DRASTIC methods: a case study of the Senirkent-Uluborlu Basin (Isparta, Turkey)

Aquifer vulnerability has been assessed in the Senirkent-Uluborlu Basin within the Egirdir Lake catchment (Turkey) using the DRASTIC method, based on a geographic information system (GIS). There is widespread agriculture in the basin, and fertilizer (nitrate) and pesticide applications have caused groundwater contamination as a result of leaching. According to hydrogeological data from the study area, surface water and groundwater flow are towards Egirdir Lake. Hence, aquifer vulnerability in the basin should be determined by water quality in Egirdir Lake. DRASTIC layers were prepared using data such as rainfall, groundwater level, aquifer type, and hydraulic conductivity. These data were obtained from hydrogeological investigations and literature. A regional-scale aquifer-vulnerability map of the basin was prepared using overlay analysis with the aid of GIS. A DRASTIC vulnerability map, verified by nitrate in groundwater data, shows that the defined areas are compatible with land-use data. It is concluded that 20.8% of the basin area is highly vulnerable and urgent pollution-preventions measures should be taken for every kind of relevant activity within the whole basin.     

Prioritization of disaster risk in a community using GIS

Prioritization of disaster risk was carried out for a community in Toronto, Canada. Geographic information systems (GIS) were used for spatial analysis, including spatial overlays and clipping for extracting spatial and attribute information related to people’s vulnerability, critical infrastructure and landuse. In order to determine disaster risk, the overall community vulnerability was evaluated by combining social, economic, physical and environmental vulnerabilities. This paper uses the propane explosion incident as the case in point to demonstrate the methodology and procedure used to evaluate risk using GIS techniques. City of Toronto spatial data have been integrated with the study area to gather landuse information, identify risk zones based on the propane storage facility location and evaluate risks. Statistics Canada 2006 census data have been used for area demographics and people’s social and economic status. Vulnerability indicators were determined based on the GIS-derived spatial and attribute data for the hazard and evacuation zones followed by a quantitative spatial risk estimation and ranking. The methodology of this study, based on the risk evaluation and prioritization conducted, can be applied to future decision making in effective landuse planning and the development of risk management strategies.     

A geophysical investigation of the Late Roman underground settlement at Aydintepe,Northeast Turkey

The Aydintepe underground settlement in northeastern Turkey is a series of subsurface galleries carved in Eocene‐aged volcanic tuff. Rescue excavations conducted by the Local Archaeological Museum of Erzurum in 1996 and 1997 uncovered a large settlement with several underground rooms linked by passages. According to the excavators, it may have been built as a hideout and shelter by the first Christians who were banished by the Romans during the 3rd century A.D. Despite its historical and touristic value, parts of the underground settlement at Aydintepe have been destroyed to make room for the construction of new buildings in the modern town. As part of a conservation strategy for this important archaeological resource, a series of ground penetrating radar (GPR) and electrical resistivity measurements were conducted along eight profiles between 2003 and 2005. GPR soundings with a 100‐MHz unshielded antenna yielded reflected hyperbolic signals with high amplitude from tunnel structures. These highamplitude signals corresponded to areas of high electrical resistivity. These anomalies allow us to determine the probable locations of tunnels within the underground settlement and they provide important data that can be used to prevent future damage from modern construction. © 2008 Wiley Periodicals, Inc.