宁镇地区地质灾害预报模型——以镇江润州区为例

宁镇地区是长江中下游地质灾害最严重的地区之一。镇江润州区虽然仅是宁镇地区的一个局部区域,但其气候和地质环境特征具有典型意义,所提出的地质灾害气象预警预报模型同样适用于整个宁镇地区,对长江中下游地区亦有借鉴作用。气候环境、降雨尤其是连续降雨或强降雨是诱发地质灾害的重要因素。润州区地质灾害主要与梅雨期总降雨量有关,其次与台汛期台风带来的降雨量有关,而与台汛期总降雨量无关。地质灾害预测预警方程应针对不同时期采用不同的预警模型：非梅雨期的预警方程采用预报日降雨量结合前5日降水之和的综合模型,梅雨期的预警方程采用梅雨期降雨总量模型。提出地质灾害气象预报预警等级应根据《国家突发公共事件总体应急预案》将等级统一划分为4级。该模型可作为完善我国现有地质灾害气象预警预报系统的参考。     

登陆台风精细结构的观测、预报与影响评估

2015年立项的国家重点基础研究发展计划项目(973计划)"登陆台风精细结构的观测、预报与影响评估"将通过进行登陆台风精细结构的野外科学试验,开展登陆台风精细结构的多源资料分析理论和方法研究,探索登陆台风精细化结构演变规律及其对风雨分布的影响机理,发展高分辨率台风数值预报模式关键技术,开展台风灾害影响(预)评估方法研究等,揭示环境因子及其自身内部的多尺度系统相互作用如何影响登陆台风精细化结构的演变,以及精细结构的演变如何影响台风风雨强度和分布,力争提高登陆台风精细结构的模拟、预报和影响评估能力。     

An integrated flood risk assessment model for property insurance industry in Taiwan

Taiwan is located in an area affected by Northwest Pacific typhoons, which are also one of the most important sources of rainfall to the island. Unfortunately, the abundant rainfall brought by typhoons frequently produces hazards. In recent years, typhoons and floods have caused serious damage, especially Typhoon Morakot in 2009. In this study, a probabilistic model is developed based on historical events which can be used to assess flood risk in Taiwan. There are 4 separate modules in this model, including a rainfall event module, a hydraulic module, a vulnerability module, and a financial loss module. Local data obtained from the Taiwan government are used to construct this model. Historical rainfall data for typhoon and flood events that have occurred since 1960, obtained from the Central Weather Bureau, are used for computing the maximum daily rainfall for each basin. In addition, the latest flood maps from the Water Resources Agency are collected to assess the probable inundation depth. A case study using the local data is carried out. Assessment is made to predict possible economic loss from different financial perspectives such as the total loss, insured loss, and loss exceeding probabilities. The assessment results can be used as a reference for making effective flood risk management strategies in Taiwan.     

Track analysis and storm surge investigation of 2017 Typhoon Hato: were the warning signals issued in Macau and Hong Kong timed appropriately?

ABSTRACT

This study investigates the storm surge caused by Typhoon Hato, which severely affected Macau, Hong Kong, and other coastal cities in China on 23 August 2017. A typhoon and storm surge coupling model demonstrated that the maximum storm surge height reached nearly 2.5?m along the coast of Macau, while that in Hong Kong was slightly below 2?m. Furthermore, a field survey of urban flooding revealed evidence of a 2.25-m inundation in downtown Macau and a 0.55-m inundation on Lantau Island, Hong Kong, which were likely exacerbated by a combination of storm surge, heavy rainfall, and surface water runoff over a complex hilly terrain. Significant wave overtopping and runup also occurred in beach and port areas. A typhoon track analysis confirmed that several comparably strong typhoons have followed similar ESE to WNW trajectories and made landfall in the Pearl River Delta in the last few decades. Although Hato was not the strongest of these storms, its forward speed of about 32.5?km/h was remarkably faster than those of other comparable typhoons. Higher levels of storm signal warnings were issued earlier in Hong Kong than in Macau, raising questions about the appropriate timing of warnings in these two nearby areas. Our analysis of the storm’s pattern suggests that both regions’ decisions regarding signal issuance could be considered reasonable or at least cannot be simply blamed, given the rapid motion and intensification of Hato and the associated economic risks at stake.     

基于显式统计原理的地质灾害区域预警方法初步研究

区域预警是提高防灾减灾意识、有效减轻地质灾害造成损失的重要手段。地质灾害显式统计预警理论考虑了地质环境变化与降雨参数等多因素的耦合作用,克服了传统单一临界雨量判据方法的局限。笔者应用地质灾害显式统计预警的基本原理,以中国的东南区为例开展应用研究。选取岩土体类型、地形起伏等12个基础地质环境因素.通过确定性系数模型(CF)综合分析了地质灾害分布与地质环境基础因素的关系.选取地质灾害"潜势度"作为地质环境优劣的指标,并进行了定量计算。选取当日雨量和一个降雨过程的前期累计雨量作为降雨激发因素的指标.采用多元回归的统计分析方法,分析了地质环境因素、降雨激发因素的耦合作用与地质灾害发育情况之间的关系.建立了显式统计的地质灾害预警预报模型。以2006年5月18日台风"珍珠"登陆期间的实况预警情况对模型进行了应用校验。验证了显式统计预警原理及模型方法的可行性和实用性。     

A new typhoon bogussing scheme to obtain the possible maximum typhoon and its application for assessment of impacts of the possible maximum storm surges in Ise and Tokyo Bays in Japan

We developed the new typhoon bogussing scheme to obtain the possible maximum typhoon approaching any region under any climatic conditions by using a potential vorticity inversion method. Numerical simulations with the new typhoon bogussing scheme are conducted for assessment of storm surges by possible maximum typhoons under the present-day and global warming climatic conditions in Ise and Tokyo Bays in Japan. The results suggest that the storm tide higher than the maximum storm tide in recorded history can occur in Ise and Tokyo Bays even for the present-day climate and the storm tide higher than the design sea level can cause severe damage to Nagoya and Tokyo megacities, in particular, airport facilities in Ise Bay for the global warming climate. These results suggest that the new typhoon bogussing scheme we developed is useful for assessment of impacts of storm surge by the possible maximum typhoons.     

Modeling beach profile changes by typhoon impacts at Xiamen coast

For the Xiamen coast where typhoon frequently occurs, beaches are subject to severe erosion during typhoons. To investigate storm-induced beach profile changes at Xiamen coast, four inner XBeach models were applied using typhoon Dan as a case study. These numerical simulations utilized hydrodynamic and wave conditions determined from larger-scale outer and middle coupled Delft3D-FLOW and SWAN models. The models were validated against historic measurements of tidal level, storm tide, storm surge and beach profiles, thus showing the accuracy of outer and middle models to provide boundary conditions and the reliability of inner models to reflect beach profile changes during a typhoon process. The applicability of this modeling approach to Xiamen coast was verified. The results also demonstrated that an enormous amount of dune face erosion occurred at the selected beaches during the typhoon Dan process and the slopes in the vicinity of zero elevation for the chosen four beach profiles all turned out to be gentler after typhoon Dan. Nevertheless, these beaches suffered different impact degrees and processes during the typhoon influence period. Compared to swash and collision regimes, overwash and inundation regimes have the ability to alter beach profile rapidly in short time. Post-storm beach profile with and without vegetation indicated that vegetation is capable of protecting coastal beaches to some extent. By running the nested models, the simulated results can be employed in the management of the beach system and the design of beach nourishment projects at Xiamen coast.

     

Decision-tree analysis on optimal release of reservoir storage under typhoon warnings

The wet and dry seasons are distinctive in Taiwan as the amount of precipitation in wet seasons accounts for over three-fourth of the total rainfall. And the water-resources management relies pretty much on the rainfall brought in by typhoons as it accounts for a significant portion of the precipitation during wet seasons. Furthermore, as the storage of reservoirs is limited due to topographical factors, the management of typhoon rainfall has always been an important issue in Taiwan. The technique of decision-tree analysis is applied in this article to determine the optimal reservoir release in advance upon the issuance of a typhoon warning by the Central Weather Bureau (CWB), and the proposed methodology may provide solution to the trade-off judgment of reservoir operations between flood control and water supply according to economic efficiency. In this article, the economic loss functions of flooding damage and water-supply shortage are assumed in linear and nonlinear conditions, and the respective expected optimal releases based on the predicted precipitation as issued by CWB are derived. The proposed methodology has been applied to the Shihmen Reservoir System, and the capabilities of the model as an aid to real-time decision-making as well as the evaluation of the economic worth of forecasts is presented.     

Joint return probability analysis of wind speed and rainfall intensity in typhoon-affected sea area

Strong wind and rainfall induced by extreme meteorological processes such as typhoons have a serious impact on the safety of bridges and offshore engineering structures. A new bivariate compound extreme value distribution is proposed to describe the probability dependency structure of annual extreme wind speed and concomitant process maximum rainfall intensity in typhoon-affected area. This probability model takes full account of the case that there may be no rainfall in a typhoon process. A case study based on the observation data of typhoon maximum wind speed and maximum rainfall intensity in Shanghai is conducted to testify the efficiency of the model. Weibull distributions with two parameters are applied to fit respective probability margins, and the joint probability distribution is constructed by Gumbel–Hougaard copula. The fitting results and K–S tests show that these models describe the original data well. The joint return periods are calculated by Poisson bivariate compound extreme value distribution we have proposed. They indicate that typhoons with no rain have smaller joint return periods, and wind speed is the main factor which impacts the change of the joint return periods.     

陕西省地质灾害气象预报预警方法研究

地质灾害气象预报预警方法是近年来地质灾害防范的热点。由于不确定因素较多,预报方法及预报精度上还有待提高。根椐我省实际情况,选取影响地质灾害发生的主要地质因素并设计了地质背景条件下各致灾因素概率模型;根椐地质灾害主要引发因素的降雨量和初步确定的降雨量临界值;选取BP神经网络模型算法进行数学运算,最终形成预报预警产品,分等级预报,在实际预报预警中取得较好的效果。     

A preliminary evaluation of the necessity of using a cumulus parameterization scheme in high-resolution simulations of Typhoon Haiyan (2013)

The Weather Research and Forecasting model was used to test the sensitivity of Typhoon Haiyan (2013) to the use of a cumulus parameterization scheme, specifically the revised Kain–Fritsch (rKF) scheme, at high horizontal resolutions with grid spacing varying from 9 to 2 km. The rKF scheme simulated the typhoon in best agreement with the observation compared with other schemes, but some fundamental drawbacks relating the rKF scheme, e.g., neglecting the momentum adjustment and being less applicable to high-resolution modeling than multi-scaled schemes, could influence the results and were discussed. Initial results showed that the typhoon track simulations benefited little from the use of the rKF scheme or a fine resolution, partially because of the similar large-scale steering flows induced by the analyzed boundary conditions used in each simulation. The influences of using the rKF scheme on typhoon intensity, size, structure, and precipitation were dependent on the grid spacing, and the most apparent changes occurred near a grid length of 4 km. At 9–4-km grid spacings, using the rKF scheme produced typhoons much stronger with more rainfall and surface latent heat flux than did using no cumulus parameterization scheme. At 3- or 2-km grid spacing, using the rKF scheme caused little changes on typhoon intensity, and the changes in precipitation and surface latent heat flux were relatively small. These results suggested that the grid spacing of 2 km for simulations using no cumulus parameterization scheme or the grid spacing of 4 km for simulations using the rKF scheme facilitated reproducing the observed Typhoon Haiyan.     

Relationships between typhoon types and debris flow disasters in Taiwan

Frequent debris flow disasters caused by heavy precipitation during the annual typhoon season are some of the most serious disasters in Taiwan. This study is on the debris flow disasters associated with the typhoons that hit Taiwan between 1986 and 2004. Typhoon data and records of debris flow disasters available for Nantou and Hualien counties in Taiwan were analyzed. The paths and rainfall characteristics of typhoons were found to have a great effect on the debris flows at these locations. Accordingly, the typhoons were grouped into four major types based on their paths and related disasters. The relationships between rainfall intensity and accumulation and debris flow are discussed for the four major typhoon types. The information may form the basis for providing useful indicators for disaster management.     

The Potential of Fuzzy Multi-objective Model for Rainfall Forecasting from Typhoons

This study applies the fuzzy multi-objective approach to forecast short-term (around 24 h) typhoon rainfall, which can be implemented without much background meteorological knowledge. The physical characteristics of 40 typhoons, including route, central pressure, central velocity and cyclonic radius, were used as the data set. The fuzzy multi-objective method mined information from the database to forecast both the depth and pattern of rainfall, which were then combined to estimate a cumulative rainfall curve. The results of calibration with reference to 40 historical typhoon events and the results of validation using another five typhoon events indicate that the proposed model has the potential to forecast short-term cumulative rainfall curves if more variables can be included and more historical typhoon events can be collected to enlarge the database.     

An empirical correlation between the occurrence of earthquakes and typhoons in Taiwan: a statistical multivariate approach

This study looks at 102 typhoons that passed nearby or traversed Taiwan from 1995 to 2011 and their potential association with ordinary earthquakes. The study found an overall association of 63.75?%. Interestingly, prior to the September 21, 1999, M _w ?=?7.6 Chi-Chi earthquake, only 4 of 24 typhoons (16.67?%) were potentially associated with the earthquakes. This figure increased substantially after the Chi-Chi earthquake to 78 typhoons being possibly associated with earthquakes (78.21?%). From the results of the chi-square test, both correlations between the typhoons and their possible triggered earthquakes before and after Chi-Chi earthquake have significant difference. The results are discussed in terms of changes in crustal conditions after the Chi-Chi earthquake and potential mechanisms, for example, heavy rainfall and atmospheric pressure causing the ordinary earthquakes. The atmospheric pressure effect predominates over the rainfall effect during the typhoon time period by statistical multivariate approach. However, to test rainfall effect is a non-neglected mechanism; seven small earthquakes without typhoon occurring near a region experiencing heavy rainfall and earthquake activity related to accumulated rainfall values from January 1995 to July 2012 are examined.     

Characteristics of recursive and non-recursive adaptive network-based fuzzy inference system models for the forecast of typhoon inundation levels

The accurate forecasting of typhoon inundation levels is vital for damage mitigation actions during such an event. The objective of this paper is to investigate the characteristics of adaptive network-based fuzzy inference system models for the forecasting of typhoon inundation levels. A novel approach of recursively using the model to achieve higher prediction lead times is proposed. The approach is advantageous in conducting water level forecasts for various prediction lead times using a single model, whereas common non-recursive models are only applicable for the designed prediction leads. In this study, a total of 6 models, with various configurations and types of recursions, are constructed based on the cross-correlations between rainfall and water level records. The performance of each model is evaluated and compared using three indices: coefficient of efficiency, relative time shift, and threshold statistics. The best recursive and non-recursive models are selected and compared with traditional approaches based on autoregressive models with exogenous input. The results show that although the recursive models display somewhat lesser but comparable forecasting capacities compared to the non-recursive models, the former models have achieved forecasts single handedly for all the prediction leads using single models only. On the other hand, although the non-recursive models exhibit better forecasting capacities, this is at the cost of using multiple models, with each designed for a specific prediction lead time. In comparison with other traditional approaches, both the recursive and non-recursive types of models demonstrate superior performance on all the aspects inspected.     

A Climatology Model for Forecasting Typhoon Rainfall in Taiwan

The continuous torrential rain associated with a typhoon often caused flood, landslide or debris flow, leading to serious damages to Taiwan. Thus, a usable scheme to forecast rainfall amount during a typhoon period is highly desired. An analysis using hourly rainfall amounts taken at 371 stations during 1989–2001 showed that the topographical lifting of typhoon circulation played an important role in producing heavier rainfall. A climatology model for typhoon rainfall, which considered the topographical lifting and the variations of rain rate with radius was then developed. The model could provide hourly rainfall at any station or any river basin for a given typhoon center. The cumulative rainfall along the forecasted typhoon track was also available. The results showed that the R² value between the model estimated and the observed cumulative rainfall during the typhoon period for the Dan-Shui (DSH) and Kao-Ping (KPS) River Basins reached 0.70 and 0.81, respectively. The R² values decreased slightly to 0.69 and 0.73 if individual stations were considered. However, the values decreased significantly to 0.40 and 0.51 for 3-hourly rainfalls, indicating the strong influence of the transient features in producing the heavier rainfall. In addition, the climatology model can only provide the average conditions. The characteristics in individual typhoons should be considered when applying the model in real-time operation. For example, the model could give reasonable cumulative rainfall amount at DSH before Nakri (2002) made landfall on Taiwan, but overestimated the rainfall after Nakri made landfall and weakened with significant reduction in convection.     

影响太湖流域的台风演变规律分析

基于台风发源地、运动路径,以及对太湖流域影响范围、降雨量等特征的分析,提出影响太湖流域台风的刻画标准。据此从1949～2010年的台风资料中遴选出230场影响太湖流域的台风。采用非参数统计、累积距平曲线及Morlet连续小波分析等方法,剖析影响太湖流域台风的频次、年内最早及最晚影响时间等参数的趋势、突变和周期性,并分析了台风与ENSO现象的关系。结果表明:影响太湖流域台风的频次和最早影响时间变化的趋势性不显著,而最晚影响时间则有显著推后的趋势;台风频次的变化呈现"少-多-少-多"波动时演变特性,并可能存在21～22a、6～8a的振荡周期;研究对太湖流域防洪减灾具有一定的指导意义。     

"云娜"台风的监视和预报

2004年“云娜”台风的监视和预报工作中，在应用常规天气资料的基础上加强了对历史热带气旋资料、天气雷达资料和过去对台风与台风暴雨分析预报研究成果的运用。在台风登陆前、登陆过程中和登陆后三个不同阶段中，应用多种资料进行有针对性的分析判断，并向防台风指挥部门及时提供信息服务，在防台工作中发挥了有效作用。，     

Performance of nested WRF model in typhoon simulations over West Pacific and South China Sea

Forecasting skill of weather research and forecasting (WRF) model in simulating typhoons over the West Pacific and South China Sea with different trajectories has been studied in terms of track direction and intensity. Four distinct types of typhoons are chosen for this study in such a way that one of them turns toward left during its motion and had landfall, while the second took a right turn before landfall. The third typhoon followed almost a straight line path during its course of motion, while the fourth typhoon tracked toward the coast and just before landfall, ceased its motion and travelled in reverse direction. WRF model has been nested in one way with a coarse resolution of 9?km and a fine resolution of 3?km for this study, and the experiments are performed with National Center for Environmental Prediction-Global Forecasting System (NCEP-GFS) analyses and forecast fields. The model has been integrated up to 96?h and the simulation results are compared with observed and analyzed fields. The results show that the WRF model could satisfactorily simulate the typhoons in terms of time and location of landfall, mean sea-level pressure, maximum wind speed, etc. Results also show that the sensitivity of model resolution is less in predicting the track, while the fine-resolution model component predicted slightly better in terms of central pressure drop and maximum wind. In the case of typhoon motion speed, the coarse-resolution component of the model predicted the landfall time ahead of the actual, whereas the finer one produced either very close to the best track or lagging little behind the best track though the difference in forecast between the model components is minimal. The general tendency of track error forecast is that it increases almost linearly up to 48?h of model simulations and then it diverges quickly. The results also show that the salient features of typhoons such as warm central core, radial increase of wind speed, etc. are simulated well by both the coarse and fine domains of the WRF model.     

A GIS-based Decision Support System for Typhoon Emergency Response in Taiwan

The effective response actions can significantly reduce the damage caused by disasters, but the emergency managers require plenty of information before setting up appropriate strategies. The data gathering and analyzing processes are complex and the time is constrained during emergency. A GIS-based decision support system was developed to enhance the emergency operations during typhoon attacks in Taiwan. The system integrates the real time rainfall monitor and forecast information, the hazard potential, and the basic spatial database to help the emergency managers making decisions efficiently.