AGRICULTURAL FLOOD ALLEVIATION BENEFIT ASSESSMENT: A CASE STUDY

The cost of flooding on farm land depends on land use, on the frequency, seasonality, duration and depth of flooding, and on water quality. This paper describes a method to calculate the average annual cost of flooding and the extra benefits or costs associated with given changes in flooding regime, illustrated by means of a simplified case study which examines the agricultural benefits of reduced summer flooding on grass in an area of environmental importance. Using hydrological and agro-economic data, the method derives the cost of individual flood events occurring in any one month for a given land use, weights these according to observed seasonality of flood flows, and derives average annual costs per hectare and for the floodplain as a whole for given levels of flood risk. The method is useful for appraising river flood alleviation schemes whereby the effects of changes in flood risk, flood seasonality or land use can be assessed.     

Who responds more to environmental amenities and dis-amenities?

It is hypothesised that different property sub-markets react to flood risk information, floods and environmental factors differently. To test this hypothesis this research uses spatial quantile regression and quasi-experimental techniques to examine property sub-market behaviour in response to availability of flood risk information and actual flood. This new contribution to the literature is based on the use of the mapping of flood risk areas in 2009 and the 2011 flooding of Brisbane, Australia, as a case study. The results show that the impact of flood risk and actual flood on property markets varies between different sub-markets. They therefore confirm the existence of property sub-markets based on property and environmental characteristics and suggest the need for differentiate mitigation policies.     

基于WGA算子—熵权法的农业洪涝灾害风险评估——以潍坊市为例

目的 为了提高农村地区洪涝灾害科学应对水平,减轻农业损失,构建了农业洪涝灾害风险评估模型,分析评估指标的灵敏度,制定科学有效的风险应对策略。方法 文章结合2018年山东潍坊市的气象、地理和社会经济资料,构建农业洪涝灾害风险评估指标体系,利用熵权法确定各指标的权重,通过WGA算子分析指标的灵敏度,并得到潍坊市风险评估值,借助GIS绘制潍坊市农业洪涝灾害风险等级图,以此为基础制定风险防范措施。结果 （1）地形高程差和河网密度的指标灵敏度最大,最大日降水量次之,暴雨频率、汛期降水量、地均农业GDP、卫生机构数量的指标灵敏程度低。（2）潍坊市致灾因子的危险性从西往东逐渐减弱;孕灾环境敏感度最强的是潍坊西部和南部的山区,地势起伏大、河流众多,极易造成洪涝灾害;潍坊市的承灾体易损性呈现出从西北到东南逐级递减的现象;防灾减灾能力较弱的地区位于潍坊市的中部。（3）潍坊市综合风险总体态势是从西南到东北逐级递减。（4）应对致灾危险,提高气象预警的及时性和准确性,适当调整农作物的播种时间;应对孕灾敏感,兴修水利工程,发展林业;应对承灾易损,注重抗涝作物的栽培,加强对农业的自救;增强防灾能力,推行相应的保险协议,科普相关的防灾减灾知识,从而减少洪涝灾害给农业带来的损失。结论 通过农业洪涝灾害风险评估模型,可掌握潍坊市各地区的风险等级,因地制宜地制定风险应对策略,为农业防灾减灾提供理论支持和政策建议。     

基于云物元模型的南京市雨洪灾害风险评估

基于城市雨洪灾害的形成机制和属性特征,从致灾因子、孕灾环境和承灾体3个方面构建城市雨洪灾害风险评估指标体系,并提出相应的分级标准。采用云模型与物元分析方法耦合建立了城市雨洪灾害风险评估的云物元模型,并对南京市2011—2016年的雨洪灾害进行风险评估,得到历年南京市的雨洪灾害风险等级。结果表明,南京市夏季的城市雨洪灾害风险都处在较高的等级,且南京市遭受高风险等级的雨洪灾害的可能性也在逐年增加。从改善排水管网密度、加强雨水蓄存设施建设、降低城市不透水面积、加大市政防洪投入和提升城市雨洪应急处理能力等方面,提出了南京市雨洪灾害风险管理应对策略。     

基于GIS的皖南地区暴雨洪涝灾害风险区划

[目的]开展对不同重现期暴雨淹没深度模拟研究,分析皖南地区不同重现期下暴雨洪涝灾害淹没情况和不同承灾体的风险区划情况,为皖南地区防洪减灾工作提供科学依据。[方法]文章采用算术平均值方法计算面雨量及雨型分布,通过广义极值分布函数拟合,得到拟合参数和不同重现期下日致洪面雨量,利用FloodArea模型计算暴雨淹没深度图谱。即利用皖南地区1961~2014年降水数据,结合人口、GDP及土地利用类型研究分析皖南地区暴雨洪涝灾害风险和区划。[结果]皖南地区各子流域暴雨日分布特征及致洪面雨量有很大区别,牧龙河、黄湓河等流域致灾暴雨普遍偏强,漳河、青弋江等流域致灾暴雨普遍偏弱。暴雨洪涝灾害风险区划的一致性表现为各类承灾体风险等级均呈现10年一遇和20年一遇重现期较小,50年一遇重现期中等,100年一遇重现期较大的特点;区域性体现在对3种承灾体空间分布差异明显,其中人口分布集中,GDP分布相对分散,建筑用地情况和人口分布基本吻合,耕地面积比人口和GDP更广泛。[结论]皖南地区暴雨洪涝灾害不同承灾体的风险区划呈现一致性和区域性特征,暴雨洪涝灾害不同重现期与人口密集区、经济发达地区、建筑用地、耕地附近的暴雨洪涝灾害风险等级呈现一致性特征。     

Flood risk and imprudence of planning in Extremadura,Spain

The natural risks of flooding inherent to Mediterranean climates is a well-known fact, but one difficult to gauge and rarely accurately in terms of space, quantity and degree. Fortunately, in Spain the national Cartographic System for Flood Areas (SNCZI) partially compensates for the deficit, calculating the probability of these natural phenomena. The present paper describes the number, location and characteristics of the homes exposed to flooding in Extremadura. The methodology used in the study reveals in great detail the clandestine homes built on land not apt for urban development (via scans and visual detection techniques using the available series of ortho-rectified aerial photographs), particularly those at flood risk (determined by SNCZI cartography). This reveals deficiencies in risk management and land use. Also, the information leads to the conclusion that current action from the Administration is ineffective in preventing any risk of flooding, and that the risk is known, but ignored.     

基于随机森林算法的洪水灾害风险评估研究

根据流域灾害系统理论,在考虑致灾因子、孕灾环境和承灾体的基础上,选取9个风险评价指标,运用样本数据进行人工识别风险并得到训练样本,采用随机森林算法构建基于随机森林的洪水灾害风险评估模型。然后采用随机森林自评估工具,分析建立的洪水灾害风险评估模型的误差和指标,同时构建支持向量机模型作为对比方案,并采用五折交叉验证方法对基于随机森林算法的洪水灾害风险评估模型和支持向量机模型进行验证。最后以海河流域邱庄段为研究对象,分别运用基于随机森林算法的洪水灾害风险评估模型和基于支持向量机模型对相同的数据集进行评估和对比,结果显示,12 h内降雨总量、洪水持续时间和土壤含水量是引发洪水的主要因素,而基于随机森林算法的洪水灾害风险评估的训练精度及测试精度均高于支持向量机模型。     

Risk communication,women’s participation and flood mitigation in Vietnam: An experimental study

Flood risk management has become important more than ever, because an escalating threat of unpredictable and extreme weather is affecting flood-prone communities. People-centred risk communication has been proposed as an effective strategy that can stimulate people to protect themselves against flood risks. However, little research with a sound theoretical underpinning has been done to examine the effectiveness of such a strategy in developing countries. We use a field experiment to analyse how risk communication can influence households’ intentions to implement mitigation measures. Our results show that communicating about the risk of floods and how to cope with floods significantly increased both threat and coping appraisals, and thereby motivated households to take more non-structural measures. While formal risk communication had certain direct effects on mitigation intention, informal risk communication percolated through psychological variables. Risk communication should focus on coping capacities for financial measures and address the problems of wishful thinking and disaster subculture of flood-prone households. Furthermore, women’s participation in risk communication did not change the intentions to take mitigation measures of the male household heads in the Vietnamese Mekong Delta.     

长江经济带城市洪涝脆弱性评估——以南京、武汉和成都为例

在全球气候变暖和海平面上升的背景下,随着城市化水平的不断提高,城市系统面临洪涝灾害的风险形势也更加严峻。构建长江经济带城市洪涝脆弱性评估模型,采用熵权法确定权重,运用模糊集对分析法判断样本所属等级,对南京、武汉和成都的城市洪涝脆弱性进行评估。结果表明:2012—2016年,南京市平均洪涝脆弱度最低,受低人口密度、建成区高绿化率以及较高经济密度作用,洪涝脆弱性整体呈下降趋势;武汉市平均洪涝脆弱度最高,由于人口密度过高、建成区绿化率过低导致洪涝脆弱性呈现恶化态势;成都市平均洪涝脆弱度位于中等,受人口密度下降、经济密度和排水管道密度上升的影响,洪涝脆弱性呈下降趋势;提出了大力发展当地经济、合理调整城市化速度、兴修排水基本设施等降低长江经济带城市洪涝脆弱性的建议。     

长江中游城市群土地利用生态风险分析——以长株潭城市群为例

为揭示城市群发展对区域生态风险的影响,以位于长江经济带的长株潭城市群为研究区,利用1993-2013年Landsat遥感数据,定量获取土地利用变化特征,并基于移动窗口的景观生态风险指数,获得区域空间连续的生态风险指数等级分布图,分析长株潭城市群土地利用动态变化及生态风险时空变化特征。结果表明,近20年来,研究区土地利用变化较为显著,建设用地呈持续增加的趋势,耕地、林地面积在波动中减少且变化明显;近20年,生态风险等级面积变化显著,低风险区波动减少,中等风险区先减少后增加,较高风险区、高风险区均波动性增加。本研究为长株潭城市群土地资源可持续利用、生态风险的有效防范,以及对城市建设用地开发边界和生态红线的确定提供了参考,也为区域生态风险定量评价提供了有效的技术方法。     

城市洪水资源化研究

综合分析城市缺水、城市灾害和洪水资源化,提出城市洪水资源化的概念,并以华南师范大学社区为例,分析洪水资源化的经济效益,建议城市在遵循生态效益最大化的原则下,化害为利,通过城市雨洪收集利用,利用水库、湖泊蓄水,引水输沙,引水冲污等措施实现城市洪水资源化。     

Implications of land use transitions and climate change on local flooding in urban areas: An assessment of 42 Indian cities

Urban development induced land transitions affect urban hydrology, resulting in increased flooding risks. Climate change-related precipitation changes are an added complexity to the flood risks of cities. This study examines the role of land use changes in determining the occurrence of urban flooding events across 42 Indian cities under current and future climate change scenarios. Landsat images for 1990, 2000, 2010, and 2017 have been processed using a hybrid classification technique to determine the land use shares for all cities. A typical event-count study using newspaper archives has been conducted to create a flooding event database. A multilevel model employing logistic mixed-effects approach was used. Future projections of the occurrence of flooding events for nine models under three climate change-related Representative Concentration Pathways (RCPs)—2.6, 4.5, and 8.5—and three urban development scenarios have been carried out. The results suggest that cities should preserve the land uses that act as a sponge—the green, open and blue spaces. As these spaces decrease, the projected flooding events increase. Under the RCP 2.6 scenario, the number of flooding events is significantly lower (95 % confidence) than under RCPs 4.5 and 8.5. The expected flooding occurrences between RCP4.5 and RCP8.5 are not significantly different (95 % confidence) for many scenarios, suggesting that Indian cities should aim for a world temperature increase of below 2 °C, or devastating consequences are imminent. This study highlights the need for Indian cities to undertake integrated spatial planning measures for a resilient, sustainable urban future.     

基于ANP-PP-SPA的区域洪灾风险评价模型研究

针对现有洪灾风险评价模型的缺陷与不足,从致灾因子、孕灾因子、承灾因子和减灾因子4个方面,通过对14项评价指标的分析与计算,构建洪灾风险评价体系。洪灾风险评价体系以网络层次分析法(ANP)求解主观权重,投影寻踪法(PP)求解客观权重,主客观综合权重与集对分析理论(SPA)耦合,构建基于ANP-PP-SPA的洪灾风险评价模型。以广东省英德市为例,验证洪灾风险评价模型的适用性。计算结果表明,英德市2016年的洪灾风险属于中等级别,符合英德市2016年的实际情况。洪灾风险评价模型不仅综合考虑了评价指标间的相互关系,还较好地体现了洪灾风险的模糊性和随机性,能够为区域洪灾风险决策和洪水管理提供科学依据。     

Coastal areas and climate change: A decision support tool for implementing adaptation measures

Climate change will be one of the main global challenges in the future. In this context cities play a key role. If, on the one hand, cities cause climate change, on the other hand, they are the places where climate change impacts are most evident, as it deeply affects the quality of life of its inhabitants. Climate change impacts are particularly relevant for coastal areas. These are characterized by a higher concentration of buildings and people in comparison to inland areas. In particular, one of the forecasted effects of climate change in these areas is the increase in coastal flooding due to rising sea levels and storm surges. The implementation of strategies and actions for the adaptation of urban areas to the impacts of coastal flooding is essential to ensure the liveability of coastal communities. Urban planning plays a key role in cities’ adaptation. However, even though the interest in this topic has been increasing, operative support and tools for planning urban adaptation in cities are in short supply, especially in coastal cities. In light of this, it has become necessary to focus on the definition of new tools responding to the needs of urban planning.Based on these observations, this paper, starting from the existing literature on coastal vulnerability indices, has developed a new index: the Coastal Resilience Index (CoRI). Thanks to the CoRI and to the use of technological innovations applied to urban planning (in particular, Geographic Information Systems), a decision support tool has been developed to identify adaptation measures aiming to reduce the impacts of coastal flooding, caused by rising sea levels and storm surges.     

Switzerland’s transition from flood defence to flood-adapted land use–A policy coordination perspective

This contribution examines Switzerland’s shift towards integrated flood risk management from a policy coordination perspective. The study applies a heuristic framework of policy coordination to explore how adaption needs promoted cross-sectoral policy coordination between hydraulic engineering and land use planning and enhanced coherence in flood policies targeting extreme flood events. To account for the temporal dimension in policy coordination, the article traces Swiss flood policies back to the early 1800s and distinguishes four phases of policy coordination. Across the four periods, the analysis focuses on (a) the drivers of policy coordination, (b) the manifestation of policy coordination in terms of policy frames, goals, instruments and subsystem involvement, and (c) the performance of policy coordination. Complemented by an in-depth case study of cross-sectoral flood policies in the Swiss canton Nidwalden findings show that the coordination between flood and land use policies has primarily been driven by three factors: (i) extreme floods as focusing events, (ii) an increasing problem pressure, and (iii) strategic reorientations in flood and land use policies. Today, flood risk management in Switzerland displays a high degree of sectoral interplay between hydraulic engineering and spatial planning. By fostering flood-adapted land uses Switzerland’s coordinated flood policies reduce the vulnerability to uncertain future changes in flood risk and strengthen the country’s capacities to mitigate damage in extreme floods events.     

农业洪涝灾害研究进展

[目的]通过对农业洪涝灾害研究使用的数据源的分析,明确农业洪涝灾害研究的现状,归纳农业洪涝灾害研究的技术与方法,分析农业洪涝灾害未来研究方向。[方法]文章以农业洪涝灾害研究所使用数据源作为索引,对基于不同数据源开展的农业洪涝灾害研究进行概述。[结果]从农业洪涝灾害研究所涉及的数据源来分析,主要包括气象水文数据、遥感数据和统计数据,从农业洪涝灾害研究所涉及的内容来分析,主要包括洪涝灾害监测、风险预警和风险评估等3个方面的内容。[结论](1)我国农业洪涝灾害研究主要为区域和小流域洪涝灾害监测和风险评估,河流、暴雨和气候与洪涝灾害、自然灾害和社会要素的洪涝灾害以及水文模型、气候模型、土壤湿度等基础研究。通过不同研究方法研究洪涝灾害风险,高度重视洪涝灾害风险管理;(2)已经形成“天—空—地”一体化洪涝灾害立体遥感监测体系,但基于遥感数据开展的农业洪涝灾害研究,主要集中在洪涝灾害监测领域,格局分析以及预警评价的研究相对薄弱;(3)农业洪涝灾害风险预警主要从脆弱性、影响性、适应性等角度对风险进行分析,得到洪涝灾害综合风险区划并进行预警;(4)地理信息系统技术是农业洪涝风险评价中的热门方法;(5)农业洪涝灾害的评估体系缺乏统一的洪涝灾害风险理论模型与评估框架;(6)我国农业洪涝风险定量评估研究较少。     

In landscape management all of us have something to say. A holistic method for landscape Preservability evaluation in a Mediterranean region

Landscape assessment methods have traditionally valued the landscape through a panel of experts with little or no participation of the population. However, after the adoption of the European Landscape Convention (ELC), the perception and the participation of the population has played an increasingly important role in landscape evaluation and planning. In this regard, the goal of this paper is to develop a model able to evaluate and integrate both the objective and subjective landscape factors into a new concept: the Preservability. This model, as well as selecting and classifying the landscape attributes according to the bio-geographic features of the study area i.e., Ricote Valley (Region of Murcia, Spain), includes two online surveys: one to assess the populatiońs landscape preferences and the other to obtain the specific weight of each objective and subjective landscape factor from a panel of experts. These landscape factors were incorporated into a GIS. To obtain the best model, the Preservability was assessed from three different approaches: objective, objective-weighted and weighted. The final results demonstrate how the Preservability weighted method returns different thresholds appropriate to the landscape attributes, the population’s perceptual preference and the protected areas. The different thresholds allows for priority areas to be identified for protection, as well as the adoption of appropriate management and planning strategies according to the landscapes characteristics, current state and uniqueness.     

平谷区城镇建设用地生态经济适宜性评价方法

研究目的:从生态保护和经济发展的角度,研究城镇建设用地的适宜性评价指标体系和评价方法,以期为城市规划和土地利用总体规划的城镇发展用地合理布局和科学评价提供有效范式。研究方法:以GIS栅格技术为支撑,利用多因素加乘复合算法和互斥性矩阵分类方法进行城镇建设用地适宜性评价,利用对比分析法佐证评价方法与结果的有效性和合理性。研究结果:平谷区城镇建设空间布局可优化为优先建设区、适度建设区、控制建设区、适度保护区、重点保护区和禁止建设区,分别占全区总面积的22.97%、12.15%、11.69%、9.93%、12.90%和30.31%;城镇建设用地适宜程度在空间上呈圈层分布特征,由平原向四周的半山区和山区逐渐降低;评价结果与平谷区城市规划成果具有较好的一致性。研究结论:提出的评价方法对城镇建设用地适宜性评价是有效的,评价结果可以为城镇建设用地规划布局提供科学依据。     

Urban development versus wetland loss in a coastal Latin American city: Lessons for sustainable land use planning

Urbanization is a primary cause of wetland loss in coastal metropolitan regions. Therefore, it challenges the preservation of biodiversity and the provision of key ecosystem services for urban settlements. These services include leisure and recreation, climate and water regulation, water purification, and especially alleviation of natural hazards. Tsunami flood mitigation is a particularly valuable regulating service provided by these wetlands, as recently evidenced during the 2010 tsunami that hit the central coast of Chile.The Concepción Metropolitan Area (CMA), located on the central coast of Chile, has experienced noticeable wetland loss in recent decades. Our study focused on the Rocuant-Andalién wetland, which has been particularly affected by urbanization. This wetland strongly contributes to flood control, and has provided effective protection against the CMA’s latest tsunamis (1835 and 2010). Based on Strategic Environmental Assessment (SEA), we have quantified urban growth over the wetland, both executed and projected under the Metropolitan Urban Plan of Concepción (MUPC). Recent loss in wetland area by urban growth has been quantified using land use and cover change (LUCC) maps from 2004 to 2014, obtained from the classification of Landsat images. Prospective changes (considering the complete MUPC deployment) have been inferred by combining the MUPC with the 2014 land cover map. In addition, we quantified the observed effect and planned urban growth on the wetland protected area, geoforms and potential flooding based on the area affected by the last Tsunami. Results show that urban areas have increased by 28% between 2004 and 2014, while future increase is expected to reach 238%. In contrast, wetland area has decreased by 10% from 2004 to 2014 and is expected to decrease by up to 32 %. Thus, the MUPC is not contributing to the mitigation of wetland loss nor the preservation of its biodiversity and ecosystem services. Implications for coastal planning are discussed.     

河流洪泛湿地的功能特征及综合开发利用--以向海湿地为例

以向海湿地为例，分析了典型的河流洪泛湿地的功能特征，即蓄洪防旱，调节径流，控制洪水，净化过滤污染物，为珍稀生物提供栖息地以及巨大的初级生产功能等。为综合开发利用河流洪泛湿地资源，提出了先获取湿地要素指标，建立评价指标体系，再做好综合开发示范，调整，恢复和保护生态系统。