Physiographic Drainage-Inundation Model Based Flooding Vulnerability Assessment

Flooding vulnerability assessment is an important issue in Taiwan since Taiwan lies within the most active tropical cyclone formation zone of the Western Pacific. Huge economic damages and losses of human lives are occurred almost every year. This study aims to evaluate flooding vulnerability of a given area subject to large-scale land developments. A scoring-based approach associated with a physiographic drainage-inundation model is developed to quantitatively evaluate vulnerability for flooding. The flooding vulnerability index defined as the product of an exposure score and a hazard score. The exposure score assesses relative losses exposed to flooding, which is determined by land-uses classification. The hazard score measures flooding severity, which is simultaneously determined by inundation depth and duration that are obtained from the inundation model for a design storm. The Yenshui River basin located in southwestern Taiwan is used an example to illustrate the proposed method. The results show that the projected urbanization plan within the Yenshui River basin would increase flooding vulnerability from 0.371 to 0.472. However, this value is reduced to 0.388 when the mitigation measure has been implemented. The obtained spatial distribution of flooding vulnerability for a design storm provides decision-makers useful information to identify hotspots of the study area and evaluate effects of flood-mitigation measure on flooding risk-reduction.     

Assessment of Agricultural Drought Vulnerability in the Guanzhong Plain,China

The Guanzhong Plain, as an important traditional agricultural area, is suffering from high frequency droughts and a trend towards more serious drought. In this paper, eight factors, precipitation, evapotranspiration, surface water availability, depth to groundwater, well yield capacity, slope, potential water storage of soil, and GDP from agriculture, are integrated into an index to represent drought vulnerability based on the overlay and index method. In this approach, according to the internal connections between factors, precipitation and evapotranspiration are integrated into the moisture index, and depth to groundwater and well yield capacity are integrated into groundwater availability. To improve the rationality and accuracy, normalization is employed to assign rating values, and the analytic hierarchy process is introduced into the weighting scheme. Two local drought monitoring datasets endorses the results of the model. The map removal sensitivity analysis indicates the vulnerability index has low sensitivity in removing each layer. The single-parameter sensitivity analysis indicates the major contribution to the vulnerability index is meteorology followed by groundwater availability and surface water availability. The vulnerability map shows the low vulnerability coincides roughly with irrigation districts on the terraces and floodplains. The northwest tableland generally has moderate vulnerability, due largely to inefficient groundwater withdrawal. The high vulnerability is concentrated at the peripheries of the plain, where agriculture is generally rain-fed without irrigation and groundwater support, and land is rugged with high slopes.     

Integrated Index for Assessment of Vulnerability to Drought,Case Study: Zayandehrood River Basin,Iran

Drought is an extended period of deficient precipitation that causes damage to crops and reducing their performance, causes temporary scarcity of water for human/livestock consumption. Over the years, various indices have been proposed to identify onset, characterize and quantify the attributes of meteorological, hydrological and agricultural drought by various researchers. Because of the spatial and temporal variability and multiple impacts of drought, it is necessary to develop an integrated index for assessment of vulnerability of this natural phenomenon. The aim of this paper is presenting an integrated index for assessment of vulnerability to drought using multiple factors which includes hydrological, meteorological, land use and other factors. Spatial information of various factors was categorized in to various sub-classes and maps were prepared in spatial domain using Geographic Information System (GIS). This study has been carried out in the Zayandehrood River basin located in west-central Iran with semi-arid region. Due to continue droughts at recent decade, this area has been chosen as a case study. The long-term climate data (1991–2011) used for assessment. The results show that Zayandehrood River basin has experienced 11 dry years, 4 normal years, and 6 wet years in the 21 years. The results have been validated with intensive field surveys.     

A Multi-imputation Method to Deal With Hydro-Meteorological Missing Values by Integrating Chain Equations and Random Forest

Water Resources Management - Imputing hydro-meteorological missing values is essential in time series modeling. Imputation of missing values was traditionally performed after an observation period,...     

Drought Vulnerability Assessment Based on a Multi-criteria Integrated Approach and Application of Satellite-based Datasets

Water Resources Management - Drought as a complex event depends on some geo-environmental parameters. The impact of this phenomenon on the economy and environment can be devastating. Recognizing...     

Analyzing the Impacts of Climatic and Physiographic Factors on Low Flow Distributions

Low flow distributions are derived using the derived distribution function approach while considering the variabilities in the dry spell and recession response time to explore the impacts of climatic and physiographic factors on low flow distributions. The low flow distributions are separately derived from the distributions of the dry spell and the recession ratio, i.e., the ratio of the dry spell to the recession response time, on the basis of the linear recession equation, and the dry spell and recession ratio are both assumed to follow normal, gamma, and lognormal distributions. The parameters of these low flow distributions are estimated from the moments of the dry spell and recession ratio series. Applications of these low flow distributions are exemplified in three basins with different hydrological and climatic conditions in China. The gamma distribution outperforms the other two distributions while describing the distributions of the dry spell and the recession ratio. The derived low flow distributions with parameters estimated from the moments of the recession ratio show good consistency with the low flow empirical distributions, and the derived distributions can be applied to estimate the flow quantiles when continuous records of the streamflow are not available. The relationships between the quantiles of the low flow distributions and the moments of climatic factors and watershed characteristic variables show that the recession ratio has the largest influence on the low flow quantiles regardless of the hydrological regime and that the second-largest influencing factor is the dry spell distribution. Meanwhile, the recession response time has a prominent influence on the low flow distributions in erratic hydrological regimes.     

Assessment of Water Resources Vulnerability and Adaptation to Climate Change

This paper provides an overview of the 'standard' methodology developed for the United States Country Studies Program on the Assessment of Water Resources Vulnerability and Adaptation to Clim ate Change. The methodology is described in more detail in accompanying articles in this issue. A standard methodology was developed for two reasons. First, for countries with little or no experience in hydrologic and water resources modelling, it provided a simple, yet appropriate set of modelling tools that could be quickly learned and applied with a limited data set. Second, it provided a consistent methodology for synthesizing results for regional and global assessments as well as cross-country and cross-regional comparisons.     

安徽省农业旱灾脆弱性综合分析与评价

旱灾是影响安徽省农业特别是粮食生产可持续发展的重要制约因素。在相同致灾强度下,灾情会随灾害脆弱性的增强而加重,因此,研究农业旱灾脆弱性对安徽省防灾减灾和农业可持续发展具有特别重要意义。根据影响旱灾脆弱性的因素和指标体系选取的原则,选择了旱灾面积比、森林覆盖率、农村人均收入等9个指标,采用加权综合评价方法对各市旱灾脆弱性进行分析,并利用聚类分析方法进行旱灾脆弱性区划。结果表明,除合肥市、阜阳市、池州市、宿州市和黄山市5个市需要采取措施降低旱灾脆弱度外,安徽省总体上农业旱灾脆弱性较弱,有较强的抗旱承灾能力。     

Drought Risk Assessment and Management

The paper presents an overview of issues related to the estimation of drought severity, the vulnerability of affected systems towards the drought hazards, the assessment of system drought risk and the required preparedness planning against droughts. To face these recurrent and temporary phenomena, a proactive approach is promoted based on technocratic support, systematic organisational and institutional structure and active public participation. Special emphasis is given to the simple and practical approaches, though scientifically sound, for the characterisation of drought episodes and the assessment of drought risk affected systems.     

Assessing and Predicting the Vulnerability to Agrometeorological Drought Using the Fuzzy-AHP and Second-order Markov Chain techniques

Water Resources Management - Vulnerabilities of different regions to drought are under the influence of different factors such as the land use, accessibility to the surface and subsurface water...     

Assessment of Hydrological Drought Revisited

A variety of indices for characterising hydrological drought have been devised which, in general, are data demanding and computationally intensive. On the contrary, for meteorological droughts very simple and effective indices such as the Standardised Precipitation Index (SPI) have been used. A methodology for characterising the severity of hydrological droughts is proposed which uses an index analogous to SPI, the Streamflow Drought Index (SDI). Cumulative streamflow is used for overlapping periods of 3, 6, 9 and 12 months within each hydrological year. Drought states are defined which form a non-stationary Markov chain. Prediction of hydrological drought based on precipitation is also investigated. The methodology is validated using reliable data from the Evinos river basin (Greece). It can be easily applied within a Drought Watch System in river basins with significant storage works and can cope with the lack of streamflow data.     

Past and Future Global Drought Assessment

Water Resources Management - Understanding the climate change impacts on drought occurrence is of great importance for comprehensive water resources management. Reconnaissance drought index (RDI)...     

荆州市洪灾社会脆弱性评价及其空间分异研究

洪灾社会脆弱性评价对于灾区减灾、政府决策与预警具有重要的指导意义。首先,利用荆州市社会经济数据,从人口、经济、就业、教育、土地利用与住房条件、交通与通讯、灾害综合管理7个方面32个指标构建洪灾社会脆弱性评价指标体系,通过因子分析确定了5个主因子:综合经济因子、农业与人口因子、逃生因子、社会保障因子、住房因子;然后计算各因子得分以及各地区洪灾社会脆弱性总得分;最后,对地区洪灾社会脆弱性进行系统聚类和GIS制图分析。空间分异结果表明:监利县的洪灾社会脆弱性最高;江陵县、公安县、洪湖市、松滋市和石首市为中高社会脆弱性地区;荆州区为中低区;沙市区为最低区。研究成果揭示了荆州地区洪灾社会脆弱性的空间分布,有利于进一步的防灾减灾。     

A Novel Method for Agricultural Drought Risk Assessment

Climate change, increased temperatures and imbalanced precipitation distributions will potentially increase the local drought risk in certain areas. Drought assessment can identify the hidden dangers of drought and provide a theoretical basis for disaster prevention and mitigation. In this paper, a new agricultural drought risk assessment method proposed from the perspective of grain yield. The first principal components of precipitation, temperature, humidity and soil moisture represent hazard factors. The sensitive yield, which represents the sensitivity, was separated from the grain yield using a regression method. Additionally, the trend component of the grain yield represents the adaptive capacity, and the crop planting area represents exposure. Based on these definitions, the concepts of unit drought risk and regional drought risk are proposed. Four cities in Heilongjiang Province, which has the highest grain yield of any province in China, were used as application examples, and the spatial and temporal variation in the agricultural drought risk were analyzed. Application example show that the method for evaluating agricultural drought presented in this paper is reasonable in a statistical sense. The process for calculating sensitivity and adaptability shows that this method is suitable for arid and semi-arid areas, where grain yield is sensitive to hazard factors, and areas where grain yield has a certain trend.

     

Topological Robustness and Vulnerability Assessment of Water Distribution Networks

The reliability of a water distribution network (WDN) is a function of several time-invariant and time-dependent factors affecting its components and connectivity, most important of which have been shown to be the network’s topology, its operating pressure, the type of key components (such as the diameter, length, material and age of water pipes) and the network’s historical performance (such as the number of previously observed failures in the network). In terms of network topology, this attribute even though generally thought as time-invariant it actually is time-dependent, as the paths in a water distribution network change over time based on the hydraulics in the network (water demand and water pressure/flow alter the way water flows in the piping network). The work described herein examines the time-dependent nature of a WDN topology and by means of a betweenness centrality index (BC) method demonstrates the effect of topology on the network’s vulnerability / reliability. The importance of the betweenness centrality index is demonstrated by use of a case-study water distribution network operated under both normal and abnormal conditions. The proposed method is also coupled with spatial mapping to indicate areas of concern in the network, and with a decision support system to assist in prioritizing actions to improve on the network’s robustness and resilience.     

A Systematic Review of Water Vulnerability Assessment Tools

The important relationship between health and water necessitates consideration of water vulnerability. Water vulnerability is contingent upon biophysical and social drivers operating at multiple scales, and is difficult to assess. This paper offers a systematic review of 50 water vulnerability assessment tools. We identify and synthesise the contents of these assessment tools (710 indicators) into five dimensions and 22 sub-dimensions and consider the extent to which they reflect environmental and social aspects. The findings are discussed in light of a holistic approach to water resources management, and specifically Integrated Water Resources Management (IWRM). Significant opportunities exist to enhance the efficacy of water vulnerability assessment tools by incorporating indicators and operational measures for social considerations (e.g., adaptation, institutions, governance) that are developed outside the context of water.     

兰州市地质灾害易损性评价

分析了兰州市地质灾害特征,总结研究了兰州市地质灾害破坏效应,划分了受灾体类型,在此基础上,进行了地质灾害社会经济易损性分区评价。地质灾害易损性评价指标体系主要由生命损失、经济损失、社会损失和环境的损失四部分构成。地质灾害的社会经济易损程度,用易损性指数来度量。兰州市社会经济易损性高区主要集中在兰州市区和阿干镇,窑街矿区以及永登县城和皋兰县城;中川机场为社会经济不易损区;社会经济中易损区主要集中在黄河、大通河、庄浪河、宛川河河谷两岸和部分地质灾害发育的山区,这些地方人口比较集中,社会经济较发达;其余大部分地区为社会经济易损性低易损性区。     

基于小世界拓扑模型的大型电网脆弱性评估算法

应用小世界网络理论研究电网中大规模连锁故障传播的内在机理，对寻找电网本身固有的脆弱性并提出有针对性的增强措施具有重要意义。文中提出了基于小世界拓扑模型的大型电网脆弱性评估的综合算法，并对电网的拓扑建模、基本特征参数的统计以及故障模拟与脆弱性评估等各部分的独立算法进行了设计，从而形成了具有良好扩展性、便于对大型电网自身结构脆弱性及大规模连锁故障机理进行深入研究的综合算法。将该算法应用在多个实际电网中，取得了较好效果，从而证实了该算法的有效性。     

Localization of Groundwater Vulnerability Assessment Using Catastrophe Theory

Groundwater vulnerability is assessed by the DRASTIC method, which is more popular among the alternatives available. The challenge taken on board is to treat its inherent subjectivity in estimating the values of the embedded weights as recommended by USEPA for all aquifers. This paper uses a catastrophe based multi-objective evaluation system and applies it to the DRASTIC method to avoid undue preferences by decision maker. Thus, catastrophe fuzzy membership functions are used to treat the dependency of state variables on control parameters and thereby to determine the weights embedded in DRASTIC parameters. The proposed method estimates the weights of DRASTIC parameters with respect to local condition of study area. The Maragheh-Bonab aquifer in Iran is under threat by agricultural and industrial activities and therefore its vulnerability is assessed by the proposed method as well as by the general and pesticide DRASTIC methods. Comparison of results with the special distribution of nitrate-N (NO3-N) shows that the improved DRASTIC has a higher correlation index with respect to the general and pesticide DRASTIC methods. Also in seeking more reliability, the addition of new parameters is possible in the proposed method.     

A Community-Structure-Based Method for Estimating the Fractal Dimension,and its Application to Water Networks for the Assessment of Vulnerability to Disasters

Water Resources Management - Most real-world networks, from the World-Wide-Web to biological systems, are known to have common structural properties. A remarkable point is fractality, which...