Flood Regulation Research Articles

Multi-objective risk analysis for flood control operation of a complex reservoir system under multiple time-space correlated uncertainties

Many uncertainties are involved in flood control operation of a multi-reservoir system and result in risks for the system. Risk analysis for reservoir flood control operation is essential for decision making. Traditional flood control risk analysis only takes flood forecast error as the main risk source, ignoring the influence of dynamic control of flood-limited water level on reservoir initial water level for flood regulation. In this study, the spatial correlation of reservoir initial water level errors and the spatiotemporal correlation of flood forecast errors are identified via copula function. A risk analysis model considering both upstream and downstream is established for multi-objective flood control operation of a complex reservoir system, coupling multi-dimensional uncertainties of reservoir initial water levels, flood forecast errors, reservoir capacity curve errors, reservoir discharge curve errors and river flood routing errors. The impact of multiple risk sources with spatiotemporal correlations on reservoir flood control operation is then evaluated and the competitive tradeoff between flood control risks in upstream and downstream analyzed. The model is applied to a mixed four-reservoir system in Pi River Basin in China. Results indicated that 1) there is a strong correlation between the reservoir initial water level errors in space and also between the flood forecast errors in space and time, which can be effectively described by copula function, and ignoring the correlations will underestimate the flood control risk; 2) the two objective values of upstream and downstream show a clear competitive relationship, and the solution that prefers one objective has low risk marginal benefit, thus choosing a compromise solution can balance risks; 3) coupling the initial water level uncertainty reduces the flood control risk caused by the flood forecast errors to a certain extent, but also lead to the increase of extreme risk loss.

Przegląd usług pełnionych przez ekosystemy miejskie w Azji Południowo-Wschodniej

Urban ecosystem services refer to all the benefits of nature especially to the urban community and economy for maintaining human well-being. This concept links to the economic, community and environmental aspects and shows how nature conservation is important for human and economic principles. However, the view of urban ecosystem services assessment based on essential categories with current urban development is provided. So, this paper reviews the aim to analyze the types and assessing the categories of urban ecosystem services and the methodological used in ASEAN countries. Furthermore, understanding studies about urban ecosystem services are important in long-term studies for monitoring purpose. As a result, 8 out of 10 ASEAN countries excluding Laos and Brunei have studied urban ecosystem services. In this context, the result also shows the most studies specify the significance of the ecosystem services given by the urban as regulating (waste absorption, climate regulation, water purification, flood regulation, and disease control) and followed by cultural (tranquility, social relations, and recreation). Thus, exploring urban ecosystem interaction in current ASEAN countries may have added benefits in terms of improving the urban ecosystem services to streamline the urban area planning. Finally, we conclude that all the ASEAN countries should play an important role to make sure the countries maintain sustainable and more livable with the right policies and guidelines like can fit in Paris Agreement especially in Climate Strategies and plans.

RUSSELL REVIEW Are plant roots only “in” soil or are they “of” it? Roots, soil formation and function

AbstractRoots are near‐ubiquitous components of soils globally but have often been regarded as separate from the soil rather than a substantial factor in determining what soil is and how it functions. The start of rapid soil formation commenced about 400 million years ago with the emergence of vascular plants and the evolution of roots and associated microbes. Roots and associated microorganisms contribute significantly to soil formation by altering rocks and soil minerals through a variety of biogeochemical processes and supply carbon to a depth that can have long residence times. Living root inputs of carbon via rhizodeposits are more efficient than shoot and root litter inputs in forming slow‐cycling, mineral‐associated soil organic carbon pools. The current functionality of soils in providing food and fuel and fibres, supplying plant nutrients, filtering water and flood regulation, and disease suppression are all dependent on the activities of plant roots. Roots are actively communicating and collaborating with other organisms for mutual benefit, and the signals underlying this modulation of the rhizosphere microbiome are being identified. In this review I examine how plant roots (an organ not an organism) affect soil formation and function and conclude that, from several perspectives, roots are not just “in” soil but “of” it and that definitions of soil should recognise this. A possible definition is: “Soils are altered surficial rock or sediment, composed of organic matter, minerals, fluids, and organisms whose formation and functionality are influenced by biogeochemical weathering and interactions of these components with plant roots.”HighlightsPaleoclimatic and paleosoil research shows the key role of roots and mycorrhiza in soil formation.Deep roots and living root inputs are substantial contributors to long‐term C storage.Root/microbe signalling facilitates mutualistic symbioses, nutrient uptake and disease suppression.Definitions of soil should explicitly include roots as an important component of the soil system.

Progress of hydrological process researches in lake wetland: A review

湖泊湿地是世界上最重要的生态系统之一，在调蓄洪水、净化环境、保护生物多样性以及为人类提供淡水和食物等方面发挥着不可替代的作用.然而，受气候变化和人类活动叠加影响，湖泊湿地水文过程发生了剧烈变化，湖泊湿地面临着面积萎缩、质量下降和服务功能退化等风险.本文总结了原位观测、数值模拟和遥感技术在获取湖泊湿地关键水文要素方面的优势及不足；从辩证的角度探讨了气候变化和人类活动对湖泊湿地水文过程的双重影响；结合洪水和水文连通性等研究热点分析了水文过程的典型表现形式；从正反两方面揭示了湖泊湿地植物、动物和水质对水文过程改变的响应.本研究最终提出未来应该将遥感技术与数值模拟方法相结合，建立多目标-多要素-多尺度-多过程的湖泊湿地监测体系；定量评价多维度水文连通的转化方式及其对生态系统的阈值效应；加强研究地下水驱动下湿地植被演变的非线性动力学机制；综合考虑栖息地的面积和质量评价水鸟种群的弹性力和恢复力，为湖泊水位调控和退化湿地的恢复提供科学依据.;As one of the most important ecosystems in the world, lake wetlands are irreplaceable in flood regulation, environment decontamination, biodiversity conservation, and in the provision of freshwater and food resources. However, lake wetlands hydrological processes have changed drastically as a result of anthropogenic activities and climate change in combination, evidenced by shrinking wetland areas, declining wetland quality, and degraded wetland service functions. Here we summarized the merits and drawbacks of field observations, numerical simulations and remote sensing in deriving key hydrological elements of lake wetlands. The dual effects of human and climate on hydrological processes were discussed dialectically, and typical forms of hydrological processes were analysed incorporating the current hotspot flood and hydrological connectivity issues, and both positive and negative responses of plants, animals and water quality to changing hydrological processes were reviewed. In the forthcoming years, a combination of remote sensing and numerical simulation will lead to a multi-objective, multi-factor, multi-scale and multi-process lake wetland monitoring system. Based on extensive observational data, the conversion paths of multi-dimensional hydrological connectivity and their thresholding effects on ecosystem will be quantified. The investigation of nonlinear driving mechanisms behind wetland vegetation-groundwater dynamics will be strengthened. The elasticity and resilience of waterfowls' population will be evaluated considering both habitat area and quality. The ultimate goal is to provide a scientific basis for lake-level regulation and wetland restoration.

国土空间生态修复与保护空间识别——以北京市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 国土空间生态修复与保护空间识别——以北京市为例 DOI: 10.5846/stxb202103150692 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重点项目（71533005）；中国科学院青年创新促进会（2013030） Spatial identification of territory space ecological conservation and restoration: A case study of Beijing Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:构建国土空间修复与保护识别体系可以有效实现区域生态系统修复与保护，然而，当前国土空间生态修复与保护研究和规划缺乏从系统性和完整性的角度识别关键生态修复与保护区。因此构建了系统的生态修复与保护空间识别方法，以实现区域协调发展、保障区域生态安全。基于该方法，以北京市为例，通过评估生态系统服务、生态系统质量和生态问题，构建生态修复与保护空间格局。研究结果表明：① 2000-2015年生态系统服务和质量退化区主要集中在平原区和密云水库北部，面积为760.4 km2；生态系统质量低下区主要分布在西南部山区和东北部山区，面积为4925 km2；水土流失问题区零星分布在山区，面积为130.1 km2；基于以上三者的北京生态修复建议区总面积5606 km2。②建议北京生态保护区6391 km2，主要分布在北部山区和西南部山区，保护了79.63%的水源涵养功能，74.97%的土壤保持功能，58.79%的洪水调蓄功能和60.3%的自然栖息地。本研究构建的生态修复与保护空间识别方法体系，为北京生态修复和保护规划与生态安全格局构建提供科学依据，还可以为其他地区的生态修复与保护规划提供参考。 Abstract:A robust identification system of territory space ecological restoration and conservation can make effective contribution to regional ecosystem restoration and conservation. However, current research and planning lack the identification of key ecological restoration and conservation areas from the perspective of systematicness and integrity. This study established a systematic spatial identification method for ecological restoration and conservation to provide basis for regional coordinated development and regional ecological security. On the basis of the method, taking Beijing as a case, the spatial pattern of ecosystem restoration and conservation was explored through assessing of ecosystem services, ecosystem quality and ecological problems. The results showed that:(1) the ecosystem quality and ecosystem services increased generally in Beijing from 2000 to 2015. Ecosystem quality of forest, shrub and grassland improved by 39%. Correspondingly, water retention service, soil conservation service and flood mitigation service increased by 11%, 3% and 10%, respectively. However, ecological degradation occurred in some regions because of nature or human activities impact. The degraded areas of ecosystem services and ecosystem quality from 2000 to 2015 were mainly concentrated in the plain and the north of Miyun Reservoir, covering a total area of 760.4 km2 dominated by farmland and urban land. The areas with low ecosystem quality were mainly distributed in the mountainous areas of southwest and northeast, covering an area of about 4925 km2 dominated by forest and shrub ecosystems. The areas with severe soil erosion were scattered in mountainous areas, covering an area of about 130.1 km2 dominated by farmland and shrub. The suggested ecological restoration regions in Beijing consisted of the above mentioned three, with a total area of about 5606 km2., accounting for 34.16% of the total area of Beijing. (2) The area of ecological conservation suggested was 6391 km2, accounting for 38.95% of the total area of Beijing, mainly distributed in the northern and southwestern mountainous areas. The forest, shrub, grassland and wetland accounted for 54.81%, 34.38%, 6.53% and 4.27% of the total area of the ecological conservation space, respectively. The ecological conservation areas of Beijing could conserve 79.63% of Beijing's water retention service, 74.97% of soil conservation, 58.79% of flood regulation and storage, and 60.3% of Beijing's natural habitat. The spatial identification system of ecological restoration and conservation constructed in this study could not only serve as scientific basis for ecological restoration and conservation planning and ecological security pattern construction in Beijing, but also provide references for ecological restoration and conservation in other areas. 参考文献 相似文献 引证文献

Evaluating the potential of aquaculture in the Hoa Binh reservoir with carrying capacity and water quality indices

Not only does the Hoa Binh reservoir play essential roles in water storage for electricity generation and flood regulation, but also it has great potential to aid aquaculture production. Presently, aquaculture production sits at around 9,200 tons/year; however, a recent MARD circular (#16 in 2015) estimated that maximum production would approach 10,000 tons/year in the productive photic zone. This paper supports increased capacity towards a sustainable commodity production model by optimizing production levels and farming practices. To reach this goal, it is necessary to determine water quality parameters using the Relative Water Quality Index (ReWQI) and carrying capacity (CC) analysis. Data was obtained from 30 sites at upstream, midstream, and downstream sections of the reservoir during the 2019 dry and wet seasons. The results from the ReWQI reflected good water quality potential (rated between 92-100) for aquaculture. The total nitrogen (TN) and total phosphorus (TP) levels of 10,794.9 kg/day and 1,965.4 kg/day, respectively, indicate high biological productivity resulting in strong fish growth potential. CC analysis and overall water quality reflect the potential for sustainable and increased productivity to 22,730.4 tons/year, which is an increase in production of over 13,200 tons/year compared to the current period. To reach a higher yield of 40 kg/year/m3 within each cage (5,040 kg/cage/year), the corresponding increase in number needs to be 4,510 cages based on a common cage size of 126 m3 (6x6x3.5 m). In order to reach these future production goals, this work concludes that the local government should begin spatial planning decisions based on appropriate cage allocation and distribution with respect for regular monitoring of water quality and nutrient load capacity of the environment to reach sustainable aquaculture development.

Increasing urban flood risk in China over recent 40 years induced by LUCC

Land use/cover change (LUCC) caused by urbanization has a great impact on urban hydrological systems, among which urban pluvial floods are particularly prominent and have attracted worldwide attention. Although some previous studies have shown that urban LUCC increases urban pluvial flood risk and reduces urban flood regulation service (UFRS) in individual cities, there has not been a nationwide quantitative assessment in China. Here, we use a data-driven hydrological model and constructed indicators to clarify the quantitative impact of LUCC on China's UFRS and its spatial pattern from 1977 to 2018. Our analysis revealed that LUCC has caused China's UFRS to decline by 13.39%, from 31.34% in 1977 to 17.95% in 2018. Spatially, the UFRS decline in all river basins in China was greater than 10%, and the UFRS in almost all cities was decreasing. Especially in the densely distributed eastern Yangtze River basin, Pearl River basin, Southeast basin, Haihe River basin and Huai River basin, their UFSR values decreased by 11.89%, 12.17%, 12.34% and 10.81%, respectively. This is a warning that China's urban land conversion has greatly increased the urban pluvial flood risk.

A Machine learning framework to predict reverse flow and water level: A case study of Tonle Sap Lake

Reliable assessment of the natural interactions in large river–lake systems is vital for water supply planning, flood regulation, and ecosystem services. The existing interaction between the Mekong River (MR), Tonle Sap River (TSR), and Tonle Sap Lake (TSL) has been further complicated due to the reverse flow phenomenon (RF) beyond ongoing anthropogenic activities and climate change. While continuous observations, insufficient data, and event-driven measurement have remained a challenge for such a large basin, accurate prediction of the RF period and water level influenced would pave the way in providing effective remedies for side effects in this area for future scenarios. In this study, the RF periods were investigated employing the K-Nearest Neighbors (KNN) and Ensemble Bagged Tree (EBT) classification algorithms that showed comparable results with observed periods. The predicted periods were then used to predict the daily water level at the confluence where the MR and TSR join using Long Short-Term Memory (LSTM) and Adaptive Neuro-Fuzzy Inference System (ANFIS) methods. Although both models yielded highly accurate water level predictions, a slightly better performance was attributed to the LSTM model. Regarding the TSR’s role in the RF period, results highlighted its significant role in extending the RF period in some years, despite its much lower streamflow than the MR. The developed model could be used as a reliable machine learning (ML) framework where there is a need for highly accurate data regarding RF and water levels for TSL and its environs.

Efficient Reservoir Modelling for Flood Regulation in the Ebro River (Spain)

The vast majority of reservoirs, although built for irrigation and water supply purposes, are also used as regulation tools during floods in river basins. Thus, the selection of the most suitable model when facing the simulation of a flood wave in a combination of river reach and reservoir is not direct and frequently some analysis of the proper system of equations and the number of solved flow velocity components is needed. In this work, a stretch of the Ebro River (Spain), which is the biggest river in Spain, is simulated solving the Shallow Water Equations (SWE). The simulation model covers the area of river between the city of Zaragoza and the Mequinenza dam. The domain encompasses 721.92 km2 with 221 km of river bed, of which the last 75 km belong to the Mequinenza reservoir. The results obtained from a one-dimensional (1D) model are validated comparing with those provided by a two-dimensional (2D) model based on the same numerical scheme and with measurements. The 1D modelling loses the detail of the floodplain, but nevertheless the computational consumption is much lower compared to the 2D model with a permissible loss of accuracy. Additionally, the particular nature of this reservoir might turn the 1D model into a more suitable option. An alternative technique is applied in order to model the reservoir globally by means of a volume balance (0D) model, coupled to the 1D model of the river (1D-0D model). The results obtained are similar to those provided by the full 1D model with an improvement on computational time. Finally, an automatic regulation is implemented by means of a Proportional-Integral-Derivative (PID) algorithm and tested in both the full 1D model and the 1D-0D model. The results show that the coupled model behaves correctly even when controlled by the automatic algorithm.

Managing flood risks in a changing climate

Managing flood risks in a changing climate

Remote sensing estimation of the flood storage capacity of basin-scale lakes and reservoirs at high spatial and temporal resolutions

The flood storage of lakes and reservoirs plays an important role in flood regulation and control in floodplains. However, the flood storage capacity of lakes and reservoirs is ineffectively quantified at the basin scale due to the limited access to in-situ data and poor quality of optical satellite images in flooding seasons. To address this, taking a typical floodplain basin (the Poyang Lake basin) in the Yangtze as a study case, radar satellite data combined with measured bathymetry and digital elevation model data were utilized to reconstruct the time series of the water inundation area and water storage change of all lakes and reservoirs larger than 1 km2 during the once-in-a-generation flood event that occurred in 2020 (termed as the 2020 flood event hereafter). Results show that the flood storage capacity of Poyang Lake can reach the maximum at 12.18 Gt, and that for other lakes and reservoirs within the basin is approximately 2.95 Gt. It indicates a total flood-storage capacity of 15.13 Gt for the basin-scale lakes and reservoirs, approximately accounting for 45.02% of the terrestrial water storage change of the basin. The storage capacity of Poyang Lake was approximately four times larger than the entirety of other lakes and reservoirs in the basin despite that its maximum water inundation area is in the proportion of 2.58 times other water bodies. This finding indicates that the Poyang Lake provided the dominant contribution to flood storage among all the lakes and reservoirs in the basin. This study introduced a remote sensing approach to quantify the flood storage capacity of basin-scale lakes and reservoirs at high spatial and temporal resolutions during the flood event, which could fill the insufficiently-quantified knowledge about dynamics of lakes and reservoirs in areas lacking full-covered in-situ data records. This study also helps to offer a quantitative basis to improve flood forecasting and control for the public authority, stakeholders, and decision-makers.

Nonstationary Design Flood Estimation in Response to Climate Change, Population Growth and Cascade Reservoir Regulation

The hydrologic data series are nonstationary due to climate change and local anthropogenic activities. The existing nonstationary design flood estimation methods usually focus on the statistical nonstationarity of the flow data series in the catchment, which neglect the hydraulic approach, such as reservoir flood regulation. In this paper, a novel approach to comprehensively consider the driving factors of non-stationarities in design flood estimation is proposed, which involves three main steps: (1) implementation of the candidate predictors with trend tests and change point detection for preliminary analysis; (2) application of the nonstationary flood frequency analysis with the principle of Equivalent Reliability (ER) for design flood volumes; (3) development of a nonstationary most likely regional composition (NS-MLRC) method, and the estimation of a design flood hydrograph at downstream cascade reservoirs. The proposed framework is applied to the cascade reservoirs in the Han River, China. The results imply that: (1) the NS-MLRC method provides a much better explanation for the nonstationary spatial correlation of the flood events in Han River basin, and the multiple nonstationary driving forces can be precisely quantified by the proposed design flood estimation framework; (2) the impacts of climate change and population growth are long-lasting processes with significant risk of flood events compared with stationary distribution conditions; and (3) the swift effects of cascade reservoirs are reflected in design flood hydrographs with lower peaks and lesser volumes. This study can provide a more integrated template for downstream flood risk management under the impact of climate change and human activities.

Green infrastructure for coastal flood protection: The longitudinal impacts of green infrastructure patterns on flood damage

The importance of implementing green infrastructure (GI) for flood protection is supported by multiple substantial cross-sectional analyses. Yet, limited longitudinal research has been conducted which addresses how to maintain and improve the configuration of GI in order to minimize the cost of losses resulting from flooding. Structural damage from devastating storm events has repeatedly imposed substantial financial burdens on local governments in coastal regions. This study longitudinally examines the impacts of changes in GI patterns on flood damage cost in coastal Texas areas. Major flood events in the 36 Texan coastal watershed counties along the Gulf of Mexico were monitored from 2000 to 2017. Along with non-spatially weighted panel data models, we developed an advanced statistical model controlling for spatially correlated errors in flood loss and predicting flood loss with a set of time-series socioeconomic and environmental control variables. The results of the spatial panel data model reveal that long-term maintenance of larger, more irregular, more dispersed, less fragmented, and less connected patterns of GI will help to reduce county-level flood damage costs per capita over time. Most importantly, protecting larger patches within a closer proximity was found to be of the utmost importance for retaining the flood regulation services provided by GI. These findings suggest that planners and natural resource managers should enhance supportive land use policies to preserve existing GI and strategically locate new implementations in order to achieve long-term flood protection.

A methodology for assessing spatio-temporal dynamics of flood regulating services

The effects of land use alteration, migration and urbanization are key aspects in flood management, as human activities can strongly influence the capacity of ecosystems to provide flood regulating ecosystem services and determine their demand.This study analyzes spatio–temporal dynamics of flood regulating ecosystem services to support watershed management planning. A methodology for mapping the supply and demand of flood regulation is proposed and applied to the Arno River basin, in central Italy. The spatial explicit analysis of flood regulating ecosystem services supply is carried out with SWAT - Soil and Water Assessment Tool, whose outputs are synthetized by two indicators to evaluate the retention capacity of each land use class originating from CORINE data sets. Quantification of demand for flood regulating ecosystem services is based on flood hazard classes derived from the existing local flood management plans (i.e., PAI-Piano per l’Assetto Idrogeologico and PGRA-Piano di Gestione del Rischio Alluvioni). Supply and demand data are then combined to obtain budget maps of flood regulating ecosystem services and their evolution, between 1990 and 2018. The results show how both demand and supply of ecosystem services have changed in the last decades, highlighting the main hotspots at the catchment and sub-catchment scales. With the increasing urbanization, the demand values have grown in the Arno floodplains, where residential, industrial and commercial zones are located. At the same time, land use changes have altered the water regulation supply, resulting in a generalized decrease of the basin capacity to provide flood regulation services. The maps and tables obtained show the fundamental role of forest and other vegetated areas whose protection is a priority to assure future flood regulation and associated co-benefits (e.g., regulation of air quality, reduction of erosion, improvement of water quality, wood fuel). The assessment of flood regulating here proposed is a powerful tool for decision makers to improve flood regulation and provides a sound base of knowledge to identify and locate flood prevention and mitigation measures.

Litter decomposition and infiltration capacities in soils of different tropical urban land covers

Healthy soil ecosystems are important for urban sustainability, because they provide the basis for ecosystem services such as flood regulation, nutrient cycling and carbon sequestration. We investigated the soils beneath five types of urban land cover in the tropical city of Singapore—secondary forest, managed grass, shrubs, trees, and trees with shrubs. We quantified the capacity of these soils to support two key ecosystem functions: litter decomposition, which we measured using a standardised tea bag method, and infiltration, which we measured using a double ring infiltrometer. Soil samples (0–20 cm depth) were collected from 120 sites and were analysed for 15 soil and vegetation properties including pH, soil organic matter content, particle size, bulk density and soil nitrogen, phosphorus and potassium. The forest sites had significantly higher leaf litter cover and canopy leaf area index than the other land cover types. Rates of litter decomposition and infiltration were highest in secondary forest, followed by trees with shrubs, and lowest in grass. Litter decomposition rates were positively related to soils with presence of soil invertebrate activity, leaf litter cover and soil nitrogen content. Infiltration rates were negatively related to soil bulk density. To optimise the delivery of soil ecosystem services in tropical cities, city managers and planners should protect any remaining fragments of forest, allow natural succession to occur, plant multi-layered vegetation with trees and shrubs, and restore urban soil by improving soil nutrients, reducing bulk density, and leaving leaf litter in situ.

Modelling flood regulation ecosystem services dynamics based on climate and land use information

The concept of ecosystem service (ES) identifies benefits that people obtain from ecosystems with contributions to human well-being. One important ES under external pressure is “flood regulation” that describes an ecosystem’s capacity to reduce flood hazards. Several related studies estimate current flood regulation ES. However, regional climate projections indicate a shift in precipitation patterns. Therefore, Climate and land use changes make it necessary to assess future supply in order to test functionality and adaptation measures. This study focuses on surface retention ES. We used two methods to show the relevance of different landscape scenarios and climate information for flood regulation ES supply: 1) hydraulic simulations with the model HEC-RAS 2) the flood retention capacity indicator suggested by the German MAES-Working group. We simulated two events: the historic flood of 2013 and future hypothetically 10% higher water levels. Furthermore, three land use change scenarios were evaluated. The model results indicate water accumulation by vegetation. Higher water levels of future climate scenarios lead to an increase in flooded areas and higher water volumes. To evaluate flood regulation capacities, an approach solely based on 2D retention areas, such as the MAES-indicator, is not sufficient. Modelling approaches deliver the opportunity for future scenario simulations.

A new multiple return-period framework of flood regulation service—applied in Yangtze River basin

An ecosystem’s flood regulation service (EFRS) is important for alleviating flood risk. Both the EFRS and the relationship between EFRS supply and demand may change across flood return periods. However, most studies only considered the EFRS under a single flood return period. In this regard, a new framework is proposed that integrates multiple flood return periods to assess the expected annual EFRS supply and demand. It also considers the upstream EFRS supply flowing from the headwaters toward the downstream. A case study in the Yangtze River Basin, China, shows that the EFRS demand increases dramatically from 25- to 200-year return periods, while the EFRS supplies remain relatively constant. In terms of the expected annual EFRSs that integrate the four return-period EFRS demands and local supplies, 47 (or 43.12%) sub-basins are found to be unsatisfied (the demand is larger than the supply). This number could be reduced to 17 (or 15.60%) sub-basins if the upstream EFRS supply is considered in comparing the EFRS supply and demand, implying the importance of a catchment-wide EFRS management, particularly protecting the upstream forests, rivers and lakes, grasslands, as well as properly regulating the dams. The proposed framework could be readily applied in other basins and shed light on a comprehensive understanding and management of the EFRSs.

城市生态保护红线划定与管理——以澳门特别行政区为例

我国澳门特别行政区是世界上人口密度最高的地区之一，人地关系紧张。随着城市和经济的发展，人类空间与生态空间失调，城市生态和人居环境问题不断加剧。在建设美丽湾区、美丽澳门和人们对美好人居环境需求的背景下，通过划定城市生态保护红线以控制和维持现有重要功能生态空间，保护和改善高敏感生态空间，维护区域生态安全显得尤为重要。基于对澳门陆域生态系统调查，结合城市和自然资源特征，从生态系统服务功能、生态系统敏感性、生物多样性分布以及现有生态保护区四个方面构建了城市生态保护红线划定方法框架，选取并评估水源涵养、雨洪调节、热岛调节、土壤保持、海岸带防护五类调节服务和生态系统服务中的休闲游憩的空间格局，水土流失敏感性和海岸带风暴潮敏感性两种生态敏感性的分布，并综合澳门具有保育价值生物的栖息地分布和现有保护区范围进行了城市生态保护红线的划定。研究结果显示，澳门城市生态保护红线区域总面积6.71km²，占研究区面积的19.79%，覆盖了44%的生态空间、12.4%的海岸线、所有的重要物种栖息地及三分之一的古树名木。依照此生态保护红线研究进一步提出针对各类红线地块的保护和管理措施。研究提出的城市生态保护红线划定思路，可以为其他城市的重要生态空间保护、修复与管理提供参考。;Macao Special Administrative Region is one of the most densely populated regions in the world, and the human-land relationship is tense. The fast development of the city and economy resulted in the imbalanced pattern of human space and ecological space, and serious problems of urban ecology and human settlement environment. In the context of building a beautiful Bay Area and a beautiful Macao, and people’s demand for a better living environment, it is particularly important to control and maintain the existing vitally functional ecological space, and to protect and improve the highly sensitive ecological space by delimiting the urban ecological conservation redlines, so as to maintain regional ecological security. Based on the survey of the terrestrial ecosystem in Macao and by combining the characteristics of the city and natural resources, this paper constructed a framework for the delineation of urban ecological conservation redlines from four aspects, i.e., ecosystem service functions, ecosystem sensitivity, biodiversity distribution and existing ecological protection zones. We selected and evaluated five types of regulation services (including water conservation, rain and flood regulation, heat island regulation, soil conservation, and coastal protection) and leisure and recreation in ecosystem services, and analyzed distribution of the sensitivity of water and soil erosion and the coastal storm surge. The results were further combined with the distribution of habitats of the species with high conservation value in Macao and the scope of the existing protected areas, and the urban ecological conservation redlines were finally delineated. The total area within the delineated Macao's urban ecological conservation redlines was 6.71 km², accounting for 19.79% of the study area, which covered 44% of the ecological space, 12.4% of the coastline, all the important species habitats and one third of the ancient famous trees. Corresponding protection and management measures were also provided according to different kinds of land parcels in this ecological conservation redlines. The proposed frame and method of urban ecological redlines delineation could also provide reference for conservation, restoration and management of important urban ecological spaces in other cities.

A GIS-Based Simulation Application to Model Surface Runoff Level in Urban Blocks

Simulation of flood inundation in urban areas longer important, given the magnitude of potential loss and disruption associated with non-river based, urban flooding. The complexity of the urban environment and lack of high-resolution topographic and hydrologic data compromise the development and implementation of models. Low impact development (LID) is technical know-how on a collection of sustainable practices that mimic natural hydrological functions including infiltration, evapotranspiration or use of surface runoff. Several studies have been carried out to discuss the impact of urbanization scenarios in reducing the urban flood risk in watershed scale in Sri Lanka. Yet, there is a gap remains in simulating the effectiveness of LID-based planning practices to reduce flood risk with the complex built form scenarios. In such a situation, this study attempts to make a significant contribution to simulate the variations of flood regulation functions under different high-intensive urban development scenarios, particularly focusing on the urban metropolitan regions. The analyses were carried out utilizing SWMM (Storm Water Management Model) which is open-source flood inundation simulation approach with the help of GIS in a more qualitative manner. The simulation results indicate that expanding built form scenarios increase the flood venerability for city functions, increasing inundation duration and LID scenarios able to reduce the surface runoff to reduce flood vulnerability at a significant level. The simulation results had been verified with the real ground situation (mean percentage change < 15.5%) which able to capture the thresholds of built form variation, as well as dynamic land uses and infrastructure supply which can be used as a tool for future planning practices and decision-making.

Biophysical and economic assessment of four ecosystem services for natural capital accounting in Italy

We present methods and results of country-based natural capital assessments for four ecosystem services (ES) in Italy. The spatial mapping and the assessment have been carried out in both physical and monetary terms for (i) crop pollination, (ii) outdoor recreation, (iii) flood regulation (iv) and water provision, using the ARIES (Artificial Intelligence for Ecosystem Services) technology, which provides and integrates the necessary data and models. Extent, supply and use accounting tables have been developed for the same ecosystem services in line with the United Nations System of Environmental Economic Accounting (UN-SEEA) guidelines and Experimental Ecosystem Accounting (EEA) initiative. This work represents a first official and nationwide assessment of ecosystem services for the Italian Government in accomplishment of the Italian law n. 221/2015, applying a variety of different models and economic valuation methods to provide systematic and replicable information on natural capital through national accounting tables. We find that land management and maintenance of the countryside and forestland, which represent the typical Italian landscape, are fundamental. Our application also identifies several modelling challenges that need to be addressed before a methodological path for integrated ecosystem and economic accounting may be considered rigorous and reliable.