Taiwan Area Research Articles

Analysis of Unidirectional Wave Spectral Characteristics in the Northeastern Waters of Taiwan

Marine energy development has been actively promoted in recent years. Analyzing wave data in the surrounding sea areas is crucial for improving wave power generator efficiency. This study collected unidirectional wave spectrum data from the northeast coastal area of Taiwan (e.g., Pengjia Islet, Fugui Cape, and NTOU). It aimed to analyze the main wave types (i.e., wind waves, swell, or mixed sea) and their proportions during the northeast and non-northeast monsoon periods. The results indicate that swell waves dominate at the NTOU buoy, while wind waves dominate at the other two stations. In addition, the analysis of wave spectra ratios revealed a low percentage of unimodal spectra (only about 0.5%), and bimodal and unformed spectra presented as predominant. Furthermore, this study also introduced a brand new JW-J wave spectrum, which combines the JW and JONSWAP spectra to describe low-frequency (swell) and high-frequency (wind wave) systems, showing superior performance compared to the Torsethaugen spectrum. Finally, this research analyzed the JW-J spectrum parameters from the Pengjia Islet and Fugui Cape stations and applied these results to the NTOU bouy for effectively describing wind/swell wave variations.

Research on Air Conditioning Energy Consumption of Elementary and Junior High School Buildings in High-altitude Areas of Taiwan

<p>台灣高山地區的中小學在冬季經常需要開暖氣以維持室內舒適溫度，但礙於教育部尚未統一暖氣使用規章，地方政府公告的暖氣使用標準也未必能滿足師生的生理需求，進而影響到學生的學習成效。根據本研究調查，全國近一半的高山中小學校舍的保暖效果不佳，學習環境嚴苛，本研究透過高山地區中小學校舍的空調耗能模擬，比較不同海拔高度、不同外牆與玻璃熱傳透率對教室冷暖房空調耗能影響，模擬結果照明EUI為7.93 [kWh/(m2.yr)，電器設備EUI為2.44 [kWh/(m2.yr)，在暖房需求較高的2200公尺校舍，提升暖房溫度1度，增加空調EUI 0.55 [kWh/(m2.yr)]；在外牆熱傳透率3.5 [W/(m2.K)]的情況下，外窗平均熱傳透率每降低0.5 [W/(m2.K)]，每年約能減少暖房空調EUI 1.16 [kWh/(m2.yr)]；在外牆熱傳透率3.5 [W/(m2.K)]的情況下提升能源效率CSPF 1級，暖房空調平均減少EUI 0.67 [kWh/(m2.yr)]。根據海拔2200公尺校舍不同樓層冷暖房空調負荷模擬，三樓教室充分接收陽光照射，暖房負荷量最低，二樓的教室則因受到最少的熱輻射，暖房負荷量最高，對於暖房空調產生較高的需求。</p> <p> </p><p>In Taiwan’s high mountain regions, winter heating is often necessary in primary and secondary schools to maintain a comfortable indoor environment. However, the absence of standardized heating regulations from the Ministry of Education and the potential mismatch with local government standards can impact students’ learning outcomes. This research survey found that nearly half of the schools in these areas lack adequate insulation, creating challenging learning environments. This study simulated air conditioning energy use in high mountain schools to assess the impact of altitude, wall properties, and glass heat transfer rates on heating and cooling energy consumption. Results showed that at 2200 meters altitude, raising the heating temperature by 1 degree Celsius increased Energy Use Intensity (EUI) by 0.55 kWh/(m2.yr). Reducing window heat transfer by 0.5 W/(m2.K) annually, with a 3.5 W/(m2.K) wall heat transfer rate, decreased EUI by about 1.16 kWh/(m2.yr). Improving energy efficiency (CSPF) by one level with the same wall heat transfer rate reduced EUI by 0.67 kWh/(m2.yr).Simulation of heating and cooling loads across different floors at 2200 meters altitude revealed that third-floor classrooms had the lowest heating load due to sunlight, while second-floor classrooms with minimal radiant heat had the highest heating demand.</p> <p> </p>

Comparative Study of Heavy Metal Blood Serum Level Between Organic and Conventional Farmers in Eastern Taiwan

Numerous studies have indicated that organic fertilizers (OFer) might contain heavy metals (HMs) that present health risks to organic farmers (OFar). This study compared the concentrations of six HMs (Zn, Ni, Cd, Cu, Pb, Cr) in the blood of two distinct groups of farmers: 30 OFar from a designated organic area in eastern Taiwan, and 74 conventional farmers (CFar) from neighboring non-organic designated regions. The findings revealed that the OFar exhibited higher levels of Zn (1202.70 ± 188.74 μg/L), Cr (0.20 ± 0.09 μg/L), and Ni (2.14 ± 1.48 μg/L) in their blood compared to the CFar (988.40 ± 163.16 μg/L, 0.18 ± 0.15 μg/L, and 0.77 ± 1.23 μg/L), respectively. The disparities in Zn, Cr, and Ni levels were measured at 214.3 μg/L, 0.02 μg/L, and 1.37 μg/L, respectively. Furthermore, among the OFar, those who utilized green manures (GM) displayed significantly elevated blood levels of Zn (1279.93 ± 156.30 μg/L), Cr (0.24 ± 0.11 μg/L), and Ni (1.94 ± 1.38 μg/L) compared to individuals who exclusively employed chemical fertilizers (CFer) (975.42 ± 165.35 μg/L, 0.19 ± 0.16 μg/L, and 0.74 ± 1.20 μg/L), respectively. The differences in Zn, Cr, and Ni levels were measured at 304.51 μg/L, 0.05 μg/L, and 1.20 μg/L, respectively. As a result, OFar should be careful in choosing OFer and avoid those that may have heavy metal contamination.

Methanovulcanius yangii gen. nov., sp. nov., a hydrogenotrophic methanogen, isolated from a submarine mud volcano in the offshore area of southwestern Taiwan.

A novel mesophilic, hydrogenotrophic methanogen, strain CYW5T, was isolated from a sediment sample of a piston core collected from submarine mud volcano MV5 located in the offshore area of southwestern Taiwan. Cells of strain CYW5T were irregular coccids, 0.5-1.0 µm in diameter and lysed easily by 0.01 % sodium dodecyl sulphate (SDS) treatment. Strain CYW5Tutilized formate or hydrogen plus carbon dioxide as catabolic substrates for methanogenesis. The optimal growth conditions were 37 °C, 0.043-0.085 M NaCl and pH 6.02-7.32. The genomic DNA G+C content calculated from the genome sequence of strain CYW5T was 56.2 mol%. The results of phylogenetic analysis of 16S rRNA gene sequences indicated that strain CYW5T represented a member of the family Methanomicrobiaceae in the order Methanomicrobiales, and was closely related to the members of the genus Methanogenium. The most closely related species was Methanogenium cariaci JR1T (94.9 % of 16S rRNA gene sequence identity). The average nucleotide identity and average amino acid identity values between strain CYW5T and members of the family Methanomicrobiaceae were 74.7-78.5 % and 49.1-64.9%, respectively. Although many of the morphological and physiological characteristics of strain CYW5T and the species of the genus Methanogenium were similar, they were distinguishable by the differences in genomic G+C content and temperature, NaCl and pH ranges for growth. Based on these phenotypic, phylogenetic and genomic results, we propose that strain CYW5T represents a novel species, of a novel genus, named Methanovulcanius yangii gen. nov., sp. nov. The type strain is CYW5T (=BCRC AR10048T=DSM 100756T=NBRC 111404T).

Utilizing Numerical Models and GIS to Enhance Information Management for Oil Spill Emergency Response and Resource Allocation in the Taiwan Waters

This study aims to establish a comprehensive workflow for developing emergency response plans for both actual and scenario oil spill incidents in the Taiwan waters while addressing the resource allocation for oil spill containment as well. This workflow comprises two vital components. The first component involves the integration of numerical tools and observational data, which includes the incorporation of wind data from sources such as the National Centers for Environmental Prediction (NCEP) or meteorological stations. Additionally, it incorporates ocean current data simulated by the semi-implicit cross-scale hydroscience integrated system model (SCHISM) into the general NOAA operational modeling environment (GNOME) model, which is a new approach for this purpose. In order to assess the efficacy of this component, two distinct case studies were conducted. The first case study focused on an incident in a northern coastal area of Taiwan under open sea conditions, whereas the second case study examined an incident within a major commercial harbor in central Taiwan. The second component of this workflow involves creating oil risk maps by integrating the results from the first component with specific geographical factors into Google Earth. These oil risk maps serve multiple purposes. They offer real-time information to emergency response commanders regarding oil spill hazard prediction, and they also enable the effective development of emergency response strategies and disposal plans for potential oil spill incidents. This is achieved by generating risk maps for various scenarios using the approach outlined in the first component. Additionally, these maps assist in the assessment and planning of resource allocation for oil containment.

Three-Dimensional Numerical Analysis on the Influence of Buttress Wall Removal Timing on the Lateral Deformation of Diaphragm Walls during Deep Excavation

Urban areas in Taiwan are densely populated with limited land. Excavation often takes place near existing buildings, necessitating protective measures for adjacent properties. Among these measures, cross walls or buttress walls are commonly employed, especially in weak foundation soils, which have seen many successful applications. These mechanisms mainly contribute to reducing lateral deformation of the diaphragm walls, ground subsidence, and excavation face uplift. However, the behavior of these walls is essentially three-dimensional, and common engineering analyses employing one-dimensional elastoplastic beam analysis cannot adequately simulate their mechanical behavior. This study utilized the PLAXIS 3D 2018 software to analyze real-life cases of buttress walls and cross walls. Then, the results of the numerical models were validated against actual field measurements, and the outcomes were satisfactory, and within the regulatory allowable values. The primary objective of this study was to find the influence of different buttress wall removal timings on the lateral deformation of the diaphragm wall. The findings suggest that the gradual removal of buttress walls will effectively control the lateral deformation of diaphragm walls during the excavation of deeper floors like mezzanines.

Differences in the healthcare needs of older adults attending primary health centers in urban and rural areas of Taiwan

PurposeAs the older adult population in Taiwan continues to increase, primary health centers (PHCs) play a crucial role in geriatric care. This study explored the differences in the PHC experiences and usage needs of older adults in urban versus rural areas.MethodsA qualitative study was conducted. Twenty-one older adults were recruited from PHCs in northern, central, southern, and eastern Taiwan. Semistructured interviews were used to collect data, and the interview guidelines included their reasons for visiting PHCs, the health-care services they received, their evaluation of the services, and the advantages and disadvantages of these centers. The data were analyzed using thematic content analysis.ResultsThe PHC usage needs of older adults in urban areas differ from those of older adults in rural areas in the following 3 aspects: (1) Medical services: older adults in rural areas demand clinics specializing in various medical domains, mobile and home medical care, and case management, whereas those in urban areas demand mobile health examinations. (2) Environment and transportation: older adults in rural areas demand diverse medical equipment, shuttle services, and accessible facilities, whereas those in urban areas demand recreational facilities. (3) Active aging: older adults in rural areas demand health education courses, and those in urban areas demand diverse senior citizen courses as well as opportunities to volunteer and build interpersonal relationships.ConclusionThe older adults in urban and rural areas had different PHC usage needs. The older adults in rural areas generally focused on medical care and transportation services in PHCs, whereas those in urban areas generally focused on health promotion as a means of social participation and active aging.

Forecasting hourly PM2.5 concentration with an optimized LSTM model

Machine learning has become a powerful tool in air quality assessment which can provide timely and predictable information, alert the public, and take timely measures to prevent deteriorating air quality. The study proposed a deep learning-based long-short term memory (LSTM) model to predict hourly PM2.5 in one of the most polluted areas in Taiwan. A series of sensitivity assessments with model settings was conducted to optimize the performance of the LSTM model. Regarding the model input parameters, aerosol optical depth, pressure, and PM2.5 concentrations from the three nearby stations were used and later showed significant improvement in the forecast results. As a result of the 1–24 h forecast in 2021, the root-mean-square error (RMSE) shows a range from 6.3 to 13.1 μg m−3, and the Pearson correlation coefficient (r) varies from 0.92 to 0.59, as compared with the observed PM2.5. The model's predictability decreases as time increases—a strong correlation (r higher than 0.7) within a 9-h PM2.5 forecast. The seasonal variation showed that the highest RMSE, about 16.2 μg m−3, was observed during the winter, which is the high-polluted season in the area. Additionally, the spatial representation of the model was examined. The model can perform an efficient and satisfied forecast in the radius of 15 km from the training station. We further compared several deep learning-based algorithms in forecasting PM2.5, and our model performs better prediction results. The deep learning–based model investigated in this study can be implemented for routine air quality monitoring in urban areas and air-quality alarms associated with public health.

Geothermal feasibility analysis inside Yangmingshan National Park, Taiwan

Geothermal power generation has gradually attracted attention due to the rise of green energy approaches in recent years. The Tatun Volcanic Group (TVG) in northern Taiwan has abundant hot springs and fumaroles, which have the potential for geothermal development. However, due to overlapping territory with Yangmingshan National Park (YNP) and the issue of high acidity in thermal water, research-oriented geothermal projects were mostly carried out in the metamorphic rock area of eastern Taiwan or outside YNP. After years of renewable energy policy from the government largely focusing on solar and wind power developments, geothermal is now being revisited in the revised direction of net-zero carbon emissions. The government is pursuing new initiatives to attract private industry players for collaboration, and advocates for special geothermal regulations and amendments to the current national park rules that facilitate resource exploration.Assuming favourable rulings for geothermal exploration are established, our study assesses the feasibility of geothermal potentials in the Tatun volcanic area by analysing multiple factors to determine the best targets for the geothermal development projects inside YNP. We select the geothermal potential map of TVG in northern Taiwan and the land use classification map of YNP as two major elements for the geological characteristics and the social limitations. Play fairway methodology is used to integrate the geological and social constraints, determining three viable targets as the geothermal development sites in Matsao, Leng-shui-keng, and Long-feng-ku areas. Maps of geologically susceptible and landslide-sensitive areas are digitized and superimposed for use in further analysis to factor in the stability of the land for protecting natural environment. According to this method, the most feasible prospect accommodating the most geothermal potential and the least damage to the landscape of the national park—once the national park regulations are moderately loosened—is the Matsao area, where great geothermal potential has been corroborated by many researches over the years.

Prediction of Changes in Functional Outcomes During the First Year After Inpatient Stroke Rehabilitation: A Longitudinal Study

ObjectiveTo identify meaningful changes in patients in 3 functional domains (basic mobility [BM], daily activity [DA], and applied cognition [AC]) after discharge from inpatient stroke rehabilitation and to identify the predictors of 1-year functional improvement. DesignA longitudinal, multicenter, prospective cohort study. SettingThe acute care wards of 3 hospitals in the Greater Taipei area of Taiwan. ParticipantsFive hundred patients with stroke in acute care wards (mean age=60±12.2 years, 62% men, N=500). InterventionsNot applicable. Main Outcome Measure(s)The Mandarin version of the Activity Measure for Post-Acute Care (AM-PAC) short forms were assessed at discharge and 3-, 6-, and 12-month follow-up. The minimal detectable change (MDC) was used to categorize changes in the scores as improved and unimproved at the 4 time points. ResultsThe mean scores of the AM-PAC BM and DA subscales substantially increased over the first 3 months after discharge (86% of participants exhibited improvement) and slightly increased during the subsequent 9 months (5∼26% of participants exhibited improvement). However, the mean score of the AC subscale decreased within the first 3 months and increased over the subsequent 9 months (22-23% of participants exhibited improvement). The BM, AC scores at discharge were the dominant predictors of subsequent functional improvement (P<.05). Patients with a higher functional stage at discharge were more likely to experience significant improvement. ConclusionThis study established the capacity of the AM-PAC to predict functional improvement in 3 domains during the early, middle, and late stages of recovery. The findings can assist clinicians in identifying patients at risk of unfavorable long-term functional recovery and providing such patients with tailored interventions during the early stage of rehabilitation.

The Impact of Recognized Features of Uncomfortable Houses on Auction Prices: A Chinese Cultural Perspective

This study examines the influence of negative Feng-shui features on the prices of foreclosures (the houses subject to court-enforced auction) in Taiwan using the Google Street View function. The research objectives are threefold. Firstly, the study aims to compare whether foreclosed houses with negative Feng-shui features have longer auction times and higher discount rates compared to those without such features. Secondly, it seeks to explore the impact of negative Feng-shui features on investors in the foreclosed house market. Lastly, the study aims to assess the varying degrees of influence of different negative Feng-shui features on foreclosure prices. The findings of this study indicate that in the metropolitan area of Taiwan, foreclosures with more negative Feng-shui features tend to have longer auction times and higher discount rates compared to those without such features. Negative Feng-shui features may cause delays in investor bidding. Among the 12 negative Feng-shui features analyzed, only the presence of “facing-temple” is found to have a negative effect on foreclosure prices. This suggests that foreclosures with the “facing-temple” feature tend to have lower prices and potentially higher discount rates. The other 11 negative Feng-shui features do not have significant effects on auction pricing. This study discovered that the “facing-temple” was a significant negative Feng-shui feature in foreclosures in Taiwan against the traditional perspective. And it provides investors’ concerns toward foreclosures and their tendency in prices of foreclosures in Taiwan.

Low-to-Moderate Arsenic Exposure and Urothelial Tract Cancers with a Long Latent Period of Follow-Up in an Arseniasis Area

BackgroundArsenic exposure can cause adverse health effects. The effects of long-term low-to-moderate exposure and methylations remain unclear.ObjectiveThis study aims to examine the association between low-to-moderate arsenic exposure and urothelial tract cancers while considering the effects of methylation capacity.MethodsIn this study, 5,811 participants were recruited from an arseniasis area in Taiwan for inorganic arsenic metabolite analysis. This follow-up study was conducted between August 1995 and December 2017. We identified 85 urothelial tract cancers in these participants, including 49 bladder and 36 upper urothelial tract cancer cases. A Cox proportional hazards model was employed.ResultsThe analyses revealed a significant association between concentrations of inorganic arsenic in water > 100 ug/L and bladder cancer occurrence, with a hazard ratio (HR) of 4.88 (95% CI 1.35–17.61). A monotonic trend was observed between concentrations of inorganic arsenic in water (from 0 to > 100 ug/L) and the incidence of urothelial tract cancer, including bladder cancer (p < 0.05) and upper urothelial tract cancers (p < 0.05). Participants with a lower primary methylation index or higher secondary methylation index had a prominent effect.ConclusionsRigorous regulations and active interventions should be considered for populations with susceptible characteristics.

Improving Health by Mitigating the Air Pollution? Mortality and Trends caused by PM2.5 in the heavy-industrial areas in southern Taiwan

Improving Health by Mitigating the Air Pollution? Mortality and Trends caused by PM2.5 in the heavy-industrial areas in southern Taiwan

The impact of sulfur dioxide in industrial areas of Taiwan during the COVID-19 epidemic period

The impact of sulfur dioxide in industrial areas of Taiwan during the COVID-19 epidemic period

Multisensory Stimuli, Restorative Effect, and Satisfaction of Visits to Forest Recreation Destinations: A Case Study of the Jhihben National Forest Recreation Area in Taiwan.

The perceived quality of the restorative environment of forest resources should be a key consideration for forest recreational areas in managing ecosystem services to provide health benefits to visitors. However, previous studies on utilizing forests as a resource for restorative services have rarely explored the simultaneous integration of on-site sensory experiences from a multisensory perspective or evaluated visitor satisfaction from a service-oriented standpoint. Therefore, this study aimed to understand the association among multisensory stimuli, perceived restorativeness, and satisfaction with visits to forest recreation areas and clarify the mediating role of perceived restorativeness in the relationship between multisensory stimuli and satisfaction. This study deployed a questionnaire and collected 458 valid responses from visitors to the Jhihben National Forest Recreation Area in Taiwan. Structural equation modeling was conducted to test the study hypotheses. The results indicated that visual sensations, auditory sensations, olfactory sensations, and tactile sensations had significant positive effects on perceived restorativeness and satisfaction and that perceived restorativeness also had a significant positive effect on satisfaction. Perceived restorativeness played a partial mediating role in this causal model. This study verified the psychological model of the relationships among a natural setting's multisensory stimuli, perceived restorativeness, and satisfaction. In practice, the findings of this study offer guidance for forest recreation areas to develop strategies for ecological services, encompassing the establishment of restorative environmental management and visitor service management approaches.

Establishment of Localized Utilization Parameters for Numerical Simulation Analysis Applied to Deep Excavations

The aim of this study was to apply deep excavation behavior prediction models in the geotechnical field to establish localized soil parameters for gravel layers. Common software tools, including PLAXIS and SoilWorks, were used extensively. Monitoring data from deep excavation cases related to gravel layers in the Xindian area of Taiwan were collected. In the background analysis, the deformation of the retaining walls was used instead of parameters typically used in deep excavation analysis. This was performed to provide the ideal range recommendations for the input parameters when conducting a numerical simulation analysis of the Xindian District stratum or similar strata. The assessment results show that when setting the fifth layer of gravel to SPT-N = 100, PLAXIS suggested a soil elastic modulus range of 7840 N to 9800 N per square meter (kN/m2), while SoilWorks recommended a range of 2450 N to 3430 N per square meter (kN/m2). These ranges allow for a reasonable estimation of the maximum wall deformation during the final excavation stage. Based on the research findings, it is recommended that when conducting an excavation analysis in gravel layers in the Xindian area of Taiwan or in similar strata, engineers should refer to the abovementioned recommended ranges when selecting the soil elastic modulus for different software programs. This will enhance the accuracy of the deformation predictions during the final excavation stage.

Personal exposure to aldehydes and potential health risks among schoolchildren in the city.

Schoolchildren are sensitive to airborne aldehyde exposures. The knowledge regarding inhalation exposure to aldehydes and the factors influencing exposure in schoolchildren is limited. This study aimed to assess the variability and potential health risks of exposure to aldehydes (including formaldehyde) in schoolchildren. The important factors affecting personal exposure to aldehydes were also explored. Forty schoolchildren were recruited from the urban and suburban areas of Taiwan for aldehyde samplings and questionnaire surveys. Personal and indoor home samples of aldehydes were collected simultaneously during warm and cold seasons. We also identified the potential variables associated with aldehyde exposure based on the participant's responses to the questionnaires using mixed-effects models. The dominant three abundant aldehydes identified in personal exposure samples were formaldehyde (geometric mean, GM = 12.2µg/m3), acetaldehyde (GM = 5.53µg/m3), and hexaldehyde (GM = 8.79µg/m3), accounting for approximately 80% of the total selected aldehydes. Higher personal exposure to aldehydes was observed during the warm season. Moreover, the within-subject variance was predominant, accounting for 66.6 to > 99.9% of the total variance in exposure. Schoolchildren had a high probability of overexposure to formaldehyde and acrolein, which resulted in an incremental lifetime cancer risk of 1.59 × 10-4 (95th percentile = 4.64 × 10-4). Season, location, household refurbishment, and indoor ventilation variables were significantly associated with personal exposure to aldehydes. The results can improve our understanding of aldehyde exposure among schoolchildren to propose mitigation strategies. These findings may be applied to further epidemiological studies.

Reassessing the presence of alien predatory mites and their prospects in the face of future climate change.

Climate change poses uncertainties in the effectiveness of classical biological control (CBC), and there is a lack of information on the establishment of natural enemy populations under present and future climatic conditions. The objective is to explore current traces of two alien predators (Neoseiulus californicus and Neoseiulus fallacis; introduced for the CBC program in the 1980s) and their future expansion under climate change in Taiwan. The results indicated that N. californicus was present in alpine orchards (e.g., Lishan and Meifeng) but N. fallacis was not found. Under current climate condition, most areas in Taiwan were deemed highly suitable for N. californicus, but not for N. fallacis, which may explain the outcomes of the CBC program. With intensifying climate change, the ranges of both species are projected to contract to varying extents in Taiwan but expand in some countries. The findings from this study can provide insights for evaluating and developing future CBC programs worldwide, and can help predict the implications of climate change on biological control efforts. © 2023 Society of Chemical Industry.

Characteristics of debris flows recorded in the Shenmu area of central Taiwan between 2004 and 2021

Abstract. The data of debris-flow events between 2004 and 2021 in the Shenmu area Taiwan are presented and discussed in this paper. A total of 20 debris-flow events were observed in 18 years. Debris flows in the Shenmu area usually occurred in the Aiyuzi Stream during the rainy season, May to September, and about once per year between 2009 and 2017. The rainfall thresholds from the observed data are proposed to be Imax⁡ (maximum hourly rainfall), R24 (24 h accumulated rainfall), and Rt (effective accumulated rainfall) of 9, 23, and 67.8 mm, respectively. The rainfall data also imply that the trend curves of intensity–duration (I–D) were different before and after 2009, which is due to the extreme rainfall event of Typhoon Morakot in 2009. The I–D curve obtained from the post-2009 data is proposed as the baseline of the debris-flow I–D relationship in the study area. The extreme rainfall event also influenced the flow speed (average 14.3 m s−1 before 2010 and 4.46 m s−1 after 2010) and the occurrence frequency of debris flows (1.83 times per year before 2009 and 0.75 times after 2009). Recent findings have indicated that the ground surface vibrational signals of debris flows are potentially useful for debris-flow early warning in terms of accumulated energy, and the characteristic frequency of debris flows in the study area was below 40 Hz. The dataset and the rainfall thresholds in this study permit comparison with other monitored catchments and are useful for global debris-flow datasets.

Detecting landslide vulnerability using anisotropic microtremors and vulnerability index

The vulnerability of the Nan-Shi-Keng landslide area in Taiwan is investigated via single-station horizontal-to-vertical spectral ratio analysis. The measurement stations in the area are arranged as follows: (1) a transverse arrangement through the landslide site along Highway No. 175 (Case 1) and (2) two longitudinal arrangements down the slope (Case 2). In Case 1, the distribution of the vulnerability index along the highway indicates that the risk of surface deformation is high on sections of the highway located outside the potential sliding zone. The low vulnerability index of highway sections within areas where the protection measures have been taken indicates that they successfully stabilize the highway and the upper slope area. In Case 2, the deformation-prone directions (i.e., the directions with the maximum vulnerability index) evaluated at various stations using anisotropic microtremor measurements of the landslide site correlate strongly with the local sliding directions obtained using conventional inclinometer measurements and telemetry monitoring. The value of the vulnerability index is related to the highway damage and soil movement behavior. Therefore, the vulnerability index serves as a useful warning parameter to locate sites with a high probability of slope failure.