Flood Regulation Research Articles

Результаты и перспективы использования гидродинамической модели распространения паводочных волн в бассейне реки Амур

A 2013 disastrous inundation occurred on the Amur River indicated the necessity of reaching new solutions for floods prevention and their negative consequences minimization. One of the possible ways is development of a method for setting the discharge hydrograph of the Bureya, Nizhne-Bureya and Zeya reservoirs, nonsynchronous with the forecasted hydrograph of the flood wave passage for flood-risky ranges of the Middle and Lower Amur on the basis of the flood wave transformation calculations. Results of the digital experiments on simulating the Amur runoff transformation with a hydrodynamic model developed by RosNIIVKh Far Eastern Branch on the basis of DHI-MIKE11 for the Middle and Lower Amur for information/analytical support of the Amur BWA activities on determination of the high-water passage regime for the reservoirs. As a result of the hydrodynamic model verification over the 2016–2017 period as a whole we obtained satisfactory estimations of the simulation quality criteria. On the basis of the simulation results analysis requirements to the boundary conditions have been formulated in addition to the determination of a range of practical tasks to be solved to adopt successfully the hydrodynamic simulation methods to the operative practice of the flood regulation in the Amur River basin including provision of the beds’ and floodplains’ morphometric and hydraulic characteristics relevance; the use of the runoff formation modern forecast hydrological models calculation data; and automation of the scenario calculations on the basis of integration with the Far Eastern Department of Hydro/meteorological Service state hydrological monitoring information system.

Reliability, sensitivity, and uncertainty of reservoir performance under climate variability in basins with different hydrogeologic settings in Northwestern United States

ABSTRACTThis study investigated how reservoir performance varied across different hydrogeologic settings and under plausible future climate scenarios. Modelling was conducted for the Santiam River Basin, OR, USA, comparing the North Santiam Basin, with high permeability and extensive groundwater (GW) storage, and the South Santiam Basin, with low permeability, little GW storage, and rapid runoff response. The coupling of projections of future temperature and precipitation from global climate models, a surface water–GW hydrologic model, and a formal Bayesian uncertainty analysis produced synthetic hydrographs of reservoir inflows. Inflow hydrographs were summarized as median and extreme future flows for inputs to a reservoir operations model. The performance of reservoir operations was evaluated as the failure to meet flood management, spring and summer environmental flows, and hydropower generation objectives. Despite projected increases in winter flows and decreases in summer flows, results provided little evidence of a response in reservoir operation performance to a changing climate, with the exception of summer flow targets. Independent of climate impacts, historical prioritization of reservoir operations played an important role in the reliability of flood regulation, demonstrating the importance of reservoir operations relative to hydrologic responses to climate change in this basin. Results also highlight how hydrologic uncertainty is likely to complicate planning for climate change in basins with substantial GW interactions.

The consequences of four land‐use scenarios for forest ecosystems and the services they provide

AbstractAnticipating landscape‐ to regional‐scale impacts of land use on ecosystems and the services they provide is a central challenge for scientists, policymakers, and resource managers. Working with a panel of practitioners and regional experts, we developed and analyzed four plausible but divergent land‐use scenarios that depict the future of Massachusetts from 2010 to 2060 to address two questions: (1) “How do the magnitude and spatial distribution of ecosystem service provisioning vary under the different land‐use regimes?” and (2) “What are the synergies and trade‐offs among direct human uses, ecosystem services, and habitat quality?” Each scenario specifies the detailed prescriptions for the major uses of the forests, including conversion to residential and commercial development, clearing new farmland, shifting silvicultural practices, and designating forests protected from development. We simulated the land‐use scenarios and their interactions with anticipated climate change by coupling statistical models of land use to the LANDIS‐II landscape model and then evaluated the outcomes in terms of the magnitude and spatial distribution of (1) direct human uses of the landscape (residential and commercial development, agricultural, timber harvest), (2) ecosystem services (carbon storage, flood regulation, nutrient retention), and (3) habitat quality (forest tree species composition, interior forest habitat). Across all scenarios, conflicts occurred between dispersed residential development and the supply of ecosystem services and habitat quality. In all but the scenario that envisioned a significant agricultural expansion, forest growth resulted in net increases in aboveground carbon storage, despite the concomitant forest clearing and harvesting. One scenario, called Forests as Infrastructure, showed the potential for synergies between increased forest harvest volume through the sustainable practices that encouraged the maintenance of economically and ecologically important tree species, and carbon storage. This scenario also showed trade‐offs between development density and water quantity and quality at the watershed scale. The process of integrated scenario analysis led to important insights for land managers and policymakers in a populated forested region where there are tensions among development, forest harvesting, and land conservation. More broadly, the results emphasize the need to consider the consequences of contrasting land‐use regimes that result from the interactions between human decisions and spatially heterogeneous landscape dynamics.

Spatial processes structuring riparian plant communities in agroecosystems: implications for restoration

The disruption of hydrological connectivity by human activities such as flood regulation or land-use changes strongly impacts riparian plant communities. However, landscape-scale processes have generally been neglected in riparian restoration projects as opposed to local conditions, even though such processes might largely influence community recovery. We surveyed plant composition of field edges and riverbanks in 51 riparian zones restored by tree planting (565 1-m2 plots) within two agricultural watersheds in southeastern Québec, Canada. Once the effects of environmental variables (hydrology, soil, agriculture, landscape, restoration) were partialled out, three models of spatial autocorrelation based on Moran's eigenvector maps and asymmetric eigenvector maps were compared to quantify the pathways and direction of the spatial processes structuring riparian communities. The ecological mechanisms underlying predominant spatial processes were then assessed by regression trees linking species response to spatial gradients to seed and morphological traits. The structure of riparian communities was predominantly related to unidirectional spatial gradients from upstream to downstream along watercourses, which contributed more to species composition than bidirectional gradients along watercourses or overland. Plant traits selected by regression trees explained 22% of species response to unidirectional upstream-downstream gradients in field edges and 24% in riverbanks, and predominantly corresponded to seed traits rather than morphological traits of the adult plants. Our study showed that even in agriculturally open landscapes, water flow remains a major force structuring spatially riparian plant communities by filtering species according to their seed traits, thereby suggesting long-distance dispersal as a predominant process. Preserving hydrological connectivity at the watershed-scale and restoring riparian plant communities from upstream to downstream should be encouraged to improve the ecological integrity of rivers running through agricultural landscapes.

Spatial fit between water quality policies and hydrologic ecosystem services in an urbanizing agricultural landscape

Sustaining hydrologic ecosystem services is critical for human wellbeing but challenged by land use for agriculture and urban development. Water policy and management strive to safeguard hydrologic services, yet implementation is often fragmented. Understanding the spatial fit between water polices and hydrologic services is needed to assess the spatial targeting of policy portfolios at landscape scales. We investigated spatial fit between 30 different public water policies and four hydrologic services (surface and groundwater quality, freshwater supply, and flood regulation) in the Yahara Watershed (Wisconsin, USA)—a Midwestern landscape that typifies tensions between agriculture, urban development, and freshwater resources. Spatial extent of water policy implementation was mapped, and indicators of hydrologic services were quantified for subwatersheds using empirical estimates and validated spatial models. We found a spatial misfit between the overall spatial implementation of water policy and regions of water quality concern, indicating a need for better targeting. Water quality policies can also be leveraged to protect other hydrologic services such as freshwater supply and flood regulation. Individual policy application areas varied substantially in their spatial congruence with each hydrologic service, indicating that not all services are protected by a single policy and highlighting the need for a broad spectrum of policies to sustain hydrologic services in diverse landscapes. We also identified where future policies could be targeted for improving hydrologic services. Joint spatial analysis of policies and ecosystem services is effective for assessing spatial aspects of institutional fit, and provides a foundation for guiding future policy efforts.

DYKE MONITORIN BY THE MEANS OF PERSISTENT SCATTERING INTERFEROMETRY AT THE COAST OF NORTHERN GERMANY

Abstract. 40 percent of the world's population are presently living in coastal areas or along the main rivers. Taking into account that the vulnerability of these areas is increasing due to sea-level rise and coastal hazards such as storm surges or extreme rainfall events accompanied with floods, the importance of safety structures such as dykes is increasing as well. Hence, a spatial distributed dyke monitoring should be part of a sustainable adaptation strategy. Due to increasing amount of SAR-data from various satellites with high spatial and temporal coverage, the means of SAR-interferometry could be an essential tool to ensure this kind of required monitoring. Given this prospect, Persistent Scattering Interferometry (PSI) will be a very suitable monitoring technique for dyke structures to identify dyke movement with the accuracy of few millimetres. This procedure focuses on pixels that show a stable scattering behaviour in a sequence of multiple SAR-scenes. In opposition to ground-measurements, the spatial coverage of this technique provides comparable results for different parts of the dyke; furthermore weak segments with particular high movements could be identified in advance. This could prevent future dyke crevasses and help to reduce risks in high-populated areas. This paper attempts to describe the potential of the PSI technique for a spatial distributed dyke monitoring at the coast in northern Germany. 21 ERS-2 scenes and 16 Envisat ASAR scenes were analysed. Those Scenes cover an area of a sea shore dyke including a flood regulation barrage and results point out the potential for this technique to monitor dyke structures. Even though the observed dyke doesn't show any significant deformation rates, the two datasets show the same signal for the whole dyke.

DYKE MONITORIN BY THE MEANS OF PERSISTENT SCATTERING INTERFEROMETRY AT THE COAST OF NORTHERN GERMANY

40 percent of the world's population are presently living in coastal areas or along the main rivers. Taking into account that the vulnerability of these areas is increasing due to sea-level rise and coastal hazards such as storm surges or extreme rainfall events accompanied with floods, the importance of safety structures such as dykes is increasing as well. Hence, a spatial distributed dyke monitoring should be part of a sustainable adaptation strategy. <br><br> Due to increasing amount of SAR-data from various satellites with high spatial and temporal coverage, the means of SAR-interferometry could be an essential tool to ensure this kind of required monitoring. Given this prospect, Persistent Scattering Interferometry (PSI) will be a very suitable monitoring technique for dyke structures to identify dyke movement with the accuracy of few millimetres. This procedure focuses on pixels that show a stable scattering behaviour in a sequence of multiple SAR-scenes. In opposition to ground-measurements, the spatial coverage of this technique provides comparable results for different parts of the dyke; furthermore weak segments with particular high movements could be identified in advance. This could prevent future dyke crevasses and help to reduce risks in high-populated areas. <br><br> This paper attempts to describe the potential of the PSI technique for a spatial distributed dyke monitoring at the coast in northern Germany. 21 ERS-2 scenes and 16 Envisat ASAR scenes were analysed. Those Scenes cover an area of a sea shore dyke including a flood regulation barrage and results point out the potential for this technique to monitor dyke structures. Even though the observed dyke doesn't show any significant deformation rates, the two datasets show the same signal for the whole dyke.

A quantitative assessment of policy options for no net loss of biodiversity and ecosystem services in the European Union

The Biodiversity Strategy of the European Union includes a target to “ensure no-net-loss of biodiversity and ecosystem services by 2020”. Many policy options can be envisioned to achieve such a no-net-loss target, mainly acting on land use and land management. To assess the effectiveness of such policies at a European Union (EU) scale, we simulated land use changes and their impacts on biodiversity and ecosystem services indicators. We analysed a Business–as-Usual scenario, and three no-net-loss scenarios. The no-net-loss scenarios included measures that aim to reduce negative impacts of land use change on biodiversity and ecosystem services, by better implementation of existing biodiversity conservation measures (Scenario 1); and enhancement of existing measures (Scenario 2); and offsetting residual impacts on areas of high biodiversity and ecosystem service value (Scenario 3).Results show that none of the scenarios achieved overall no-net-loss. Compared to a Business-as-Usual scenario, the no-net-loss scenarios reduced the overall degree of land cover change at EU level, hence reducing impacts on biodiversity and ecosystem services in large parts of the EU. The more comprehensive no-net-loss scenarios resulted in a gain of natural land cover. Moreover, natural areas became better connected, especially in peri-urban areas as a result of impact avoidance and offsetting. Richness of farmland bird species was projected to increase. Measures included in the no-net-loss scenarios had net positive effects on pollination and carbon sequestration, neutral effects on crop production, erosion prevention and flood regulation, and negative effects on nature-based recreation, compared to Business-as-Usual. In particular circumstances policy measures invoked displacement effects in land use allocation, reducing the effectiveness of the measures. This was primarily the case for flood regulation services throughout the EU.This study differentiates the potential effectiveness of a no-net-loss policy framework in three manners: (i) considering biodiversity and ecosystem services simultaneously; (ii) in the light of existing policies and land use pressures; and (iii) in different land use contexts across the EU. Taken together, we conclude that achieving no-net-loss for biodiversity and ecosystem services throughout the EU remains challenging given high land use demands. Nevertheless, in large parts of Europe there appears room for improvement for certain kinds of biodiversity and ecosystem services compared to Business-as-Usual, while still meeting other land use demands.

Modeling the effects of urban expansion on natural capital stocks and ecosystem service flows: A case study in the Puget Sound, Washington, USA

Urban expansion and its associated landscape modifications are important drivers of changes in ecosystem service (ES). This study examined the effects of two alternative land use-change development scenarios in the Puget Sound region of Washington State on natural capital stocks and ES flows. Land-use change model outputs served as inputs to five ES models developed using the Artificial Intelligence for Ecosystem Services (ARIES) platform. While natural capital stocks declined under managed (1.3–5.8%) and unmanaged (2.8–11.8%) development scenarios, ES flows increased by 18.5–56% and 23.2–55.7%, respectively. Human development of natural landscapes reduced their capacity for service provision, while simultaneously adding beneficiaries, particularly along the urban fringe. Using global and local Moran’s I, we identified three distinct patterns of change in ES due to projected landuse change. For services with location-dependent beneficiaries – open space proximity, viewsheds, and flood regulation – urbanization led to increased clustering and hot-spot intensities. ES flows were greatest in the managed land-use change scenario for open space proximity and flood regulation, and in the unmanaged land-use change scenario for viewsheds—a consequence of the differing ES flow mechanisms underpinning these services. We observed a third pattern – general declines in service provision – for carbon storage and sediment retention, where beneficiaries in our analysis were not location dependent. Contrary to past authors’ finding of ES declines under urbanization, a more nuanced analysis that maps and quantifies ES provision, beneficiaries, and flows better identifies gains and losses for specific ES beneficiaries as urban areas expand.

Changes of the flood regulation capacity at Lake Dongting since 1950s

针对洞庭湖区淤积、围垦和江湖关系变化对湖泊调蓄功能的影响,根据洞庭湖调蓄属于典型复合洪水波的实际情况,提出利用离散小波分解和计算入、出湖径流过程方差的方法揭示1950s以来洞庭湖调蓄特征及其实际调蓄作用的多年变化.结果发现:洞庭湖削减的洪峰主要是32 d以下的中短尺度洪水波,其全年整体削峰系数在0.13~0.56之间;从入、出湖径流方差多年变化体现的调蓄效果看,洞庭湖区近几十年淤积围垦虽然极大地改变了湖区面积和容积,但并未使湖泊调蓄作用发生大的变化.结合洞庭湖削峰系数与城陵矶-螺山段水位落差的对应关系,认为在整个江湖系统关系中洞庭湖的调蓄能力是被动的,其变化主要取决于城陵矶以下河段过水能力对洞庭湖泄流的制约.从整个江湖关系下的洞庭湖调蓄变化特征看,1990s以来湖区小水大灾的原因之一是入湖径流过程的短尺度方差和削峰系数较大,本质上是由荆江裁弯和三峡运行导致的江湖关系变化引起的长江螺山段出流使出湖径流方差减小造成的.;In view of flood regulation capacity at Lake Dongting affected by reclamation, deposition and change of lake-river relationship, the characterization, mechanism and impact of the flood regulation capacity since 1950s were analyzed by using methods of wavelet decomposition and corresponding standard deviation amplitude. The results indicated that the flood regulation of the lake is mainly functioned on the high frequency foods with an average flood peak removing coefficient between 0.13-0.56. Although reclamation and deposition had largely decreased the water storage capacity of Lake Dongting, the flood regulation capacity did not change much revealed by the difference of standard deviation between inflow and outflow in a long term. The area and water storage capacity are only static parameters for the capacity of flood regulation at Lake Dongting. In term of the perspective of lake-river relationship, the dynamic of flood regulation capacity was mainly affected by the stage-discharge relation at the outlet of the lake, which is decided by the river channel morphology. The major reason for the phenomenon of normal discharge but high water level can be explained by the high standard deviation of inflow and the big flood peak removing coefficient, essentially resulting from the decrease of discharge deviation in the Luoshan channel of the Yangtze River which was caused by the channel straightening in the downstream of the Three Gorges.

扎龙湿地生态系统服务价值评价

PDF HTML阅读 XML下载 导出引用 引用提醒 扎龙湿地生态系统服务价值评价 DOI: 10.5846/stxb201405161006 作者: 作者单位: 中国林业科学研究院湿地所 作者简介: 通讯作者: 中图分类号: 基金项目: 林业公益性行业科研专项(201204201) Evaluation of ecosystem services in the Zhalong wetland Author: Affiliation: Institute of Wetland Research, Chinese Academy of Forestry 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:从避免重复计算的角度出发,将湿地生态系统服务分为最终服务和中间服务两部分,以最终服务的价值作为湿地生态系统服务的总价值。以扎龙湿地为例,其最终服务包括物质生产、土壤保持、水质净化、气候调节、固碳、调蓄洪水、大气调节、休闲旅游、科研教育和授粉服务,中间服务包括净初级生产力、营养循环、涵养水源、地下水补给和生物多样性维持服务,采用市场价值法、替代成本法和旅行费用法等生态经济学方法对扎龙湿地的生态系统服务进行了评价。结果表明,2011年扎龙湿地生态系统服务总价值为679.4亿元,中间服务价值为471.5亿元,各项最终服务的价值大小为气候调节>调蓄洪水>大气调节>固碳>休闲旅游>授粉服务>物质生产>水质净化>科研教育>土壤保持。扎龙湿地不仅是重要的蓄洪区和泥碳储存地,在区域气候调节方面也起着巨大的作用。针对扎龙湿地的管理,应该保护和恢复湿地面积,同时注意适当的增加旅游。 Abstract:Ecosystem service evaluations play an important role in the management and conservation of wetlands. However, current evaluation methods may count some services twice, and may not reflect the actual value of an ecosystem. In order to avoid the repeat accounting, this study divides wetland ecosystem services into ultimate services and intermediate services, and then uses ultimate services as the gross value of ecosystem services provided by the wetland. Here, we present a case study on the Zhalong wetland. The ultimate services accounted for include substance production, soil conservation, water purification, climate regulation, carbon fixation, flood regulation, gas regulation, recreation, science and education, and pollination. Intermediate services include net primary production (NPP), nutrient cycling, water conservation, groundwater recharge, and biodiversity maintenance. The methods employed in evaluating ecosystem services include the market value method, the replacement cost method, and the travel cost method. The results indicate the gross value of ecosystem services provided by Zhalong wetland is 67.94 billion Yuan RMB, and the value of the intermediate services is 47.15 billion Yuan RMB. The ranking of ultimate services in the decreasing order is as follows:climate regulation (420.00 × 108 Yuan RMB), flood regulation (226.00 × 108 Yuan RMB), gas regulation (17.35 × 108 Yuan RMB), carbon fixation (8.6 × 108 Yuan RMB), recreation (3.86 × 108 Yuan RMB), pollination (1.74 × 108 Yuan RMB), substance production (1.43 × 108 Yuan RMB), water purification (0.3 × 108 Yuan RMB), science and education (0.08 × 108 Yuan RMB), and soil conservation (0.03 × 108 Yuan RMB). The findings suggest Zhalong wetland is not only essential for regulating floods and storing carbon dioxide, but also plays an important role in regulating climate change. We suggest wetland management should aim to conserve wetland areas and increase tourism development in a balanced manner. 参考文献 相似文献 引证文献

Interpreting the impact of flood forecasts by combining policy analysis studies and flood defence

Flood forecasting is necessary to save lives and reduce damages. Reducing damages is important to save livelihoods and to reduce the recovery time. Flood alerts should contain expected time of the event, location and extent of the event. A flood alert is not only one message but part of a rehearsed flow of information using multiple canals. First people have to accept the fact that there might be a threat and what the threat is about. People need a reference to understand the situation and be aware of possible measures they can take to assure their own safety and reduce damages. Information to the general public has to be consistent with the information used by emergency services and has to be very clear about consequences and context of possible measures (as shelter in place or preventive evacuation). Emergency services should monitor how the public is responding to adapt their communication en operation during a crisis. Flood warnings and emergency services are often coordinated by different government organisations. This is an extra handicap for having consistent information out on time for people to use. In an information based society, where everyone has twitter, email and a camera, public organisations may have to trust the public more and send out the correct information as it comes in. In the Netherlands Rijkswaterstaat, the National Water Authority and the National Public Works Department, is responsible for or involved in forecasting in case of floods, policy studies on flood risk, policy studies on maintenance, assessment and design of flood defences, elaborating rules and regulations for flood defences, advice on crisis management to the national government and for maintaining the main infrastructure in the Netherlands (high ways and water ways). The Water Management Center in the Netherlands (WMCN) has developed a number of models to provide flood forecasts. WMCN is run for and by all managers of flood defences and is hosted by Rijkswaterstaat. Other organisations use these forecasts to define the consequences of the forecast, to take measures (as the evacuation of camping places on rivers banks or lake shores) or to estimate the conditional probability of failure of a flood defence. Increasing the resilience of the population by disseminating information from both policy studies (flood scenarios) and flood forecasts has been the project goal of the MEGO project “Module Evacuatie Grote Overstromingen”, an information tool for large scale evacuation due to floods. This information is available on a national website. The MEGO project has focussed on making the information from two major policy studies on flood risk available, the first sturdy determined new risk-based standards for flood defences (WV21). The second study determined the current flood risk (VNK-2). The MEGO database contains a selection of verified flood scenario’s. For each scenario the hydraulic loads which will cause a flood are known as are the probabilities of flooding and predicted casualties and damages. Overland flow maps are available. MEGO combines this data with the flood forecast, open data of the “Cadastre” (national Registry), the national digital terrain model (AHN) and the main infrastructure (local, regional and national). The site offers prepared and real time maps for professionals during a crisis, and tools to increase risk awareness for citizens. The software was recently renamed national water and flood information system, “Landelijk Informatiesysteem Water en Overstromingen (LIWO) ’ when it went live in 2016. In LIWO the second goal of MEGO was realized, by adding the information from flood forecasts. It is an open source model.

Обоснование возможности использования защитных дамб для регулирования паводкового стока.

Effect of the flood regulation with the river floodplains was discussed, and a mechanism of the flood wave transformation with the basin channel network in the natural regime and during the floodplain banking was characterized. The possibility of dikes’ capacity use for cutting off the flood peak in extreme situations was substantiated and the relevant Chinese experience was analyzed. Theoretical basis for the channel network capacity management with pre-planned flooding of the “protected” floodplain areas was presented. The appropriated methods were developed; they included plotting of the maximal runoff calculated hydrographs, concurrent simulation of the flood wave passage and dikes capacities filling, more precise definition of parameters of the water-passing facilities in the dike body. Proposals on the designing of floodplain volumes and dikes intended for the flood runoff regulation were formulated. The Ingoda River (Transbaikal Kray) was taken as a study case. It was characterized by the flood maximal flows passage in different reaches due to the regulating impact of the bed and floodplain. Comparison of the real flood passage with the simulation results with the use of floodplain regulating capacities for this river was presented. Tentative results were the evidence of the principal possibility of the dikes capacity use in extreme conditions.

Ecological Aspect of Dam Design for Flood Regulation and Sustainable Urban Development

Many floodplains are excluded from urban development because the floods cause considerable damage to people’s lives and properties. This requires the development of new approaches to flood management and mitigation for support sustainable urban development. In present study as the measures for mitigation of flash floods, the regulation of river flow by the system of detention reservoirs for flood diversion with dams, which do not need any operation management, are analyzed concerning of Far East region of Russia. The main objective of this paper is to develop a method for analysis how the dam site selection meets the environmental criterion. The method to justify a selection of self-regulated flood dam parameters, primarily a height of a dam and its location on a water stream, providing minimization of impact on the environment have been developed. The result for Selemdzha river basin in Far East monsoon region of Russian Federation is analyzed. The result shows the robustness of the method.

最大クラス台風を想定した淀川流域における洪水流出シミュレーション

A largest-class flood caused by a typhoon under a climate change condition at the Yodo River basin is examined by using rainfall data developed by a physically-based course ensemble typhoon experiment for the Isewan Typhoon in 1959 and a distributed rainfall-runoff model including flood regulation with dam reservoir operation. Simulated flood discharge at the Hirakata station under a pseudo global warming condition is analyzed, and it is found that the peak flood discharge at the Typhoon 18 in 2013 is larger than the largest peak discharge estimated by the Isewan Typhoon course ensemble simulation under a pseudo global warming condition. Magnitudes of floods with different return periods of rainfall patterns for the Isewan Typhoon and the Typhoon 18 in 2013 are also examined for evaluating the effect of flood control by dam reservoirs in the basin.

Statistical approach to flood disaster management and risks reduction - in IBU River Basin

In the past four decades, economic losses due to flood have increased tremendously and resulted in major loss of human lives and livelihoods, the destruction of economic and social infrastructure, as well as environmental damage. This study focuses on flood disaster management through the establishment of a flood prediction model for Ibu River, a major tributary of the Ona River using the statistical approach. The Hazen plotting position was used to calculate the flood return periods while the floods were fitted into log-Pearson Type III distribution to obtain extreme flood estimate. Estimates showed that extreme floods are expected to occur between the months of June and October when rainfall is prominent within the basin area. In addition, flood magnitudes were found to increase with an increase in return periods in the Hazen plotting position. The model Q = 27.89Tr 0.548 (R 2 = 0.97) generated from fitting the extreme values (peaks) of the River Ibu into the log-Pearson type III distribution, can reduce flood risks within the River Ibu basin, particularly in Sagamu, and this information is highly helpful to hydrologists and engineers in planning for flood regulation and protection measures. Keywords : Ibu River, Hazen Plotting Position, Log-Pearson Type III Distribution, Peaks, Flood Regulation

Statistical approach to flood disaster management and risks reduction - in IBU River Basin

In the past four decades, economic losses due to flood have increased tremendously and resulted in major loss of human lives and livelihoods, the destruction of economic and social infrastructure, as well as environmental damage. This study focuses on flood disaster management through the establishment of a flood prediction model for Ibu River, a major tributary of the Ona River using the statistical approach. The Hazen plotting position was used to calculate the flood return periods while the floods were fitted into log-Pearson Type III distribution to obtain extreme flood estimate. Estimates showed that extreme floods are expected to occur between the months of June and October when rainfall is prominent within the basin area. In addition, flood magnitudes were found to increase with an increase in return periods in the Hazen plotting position. The model Q = 27.89Tr0.548 (R2 = 0.97) generated from fitting the extreme values (peaks) of the River Ibu into the log-Pearson type III distribution, can reduce flood risks within the River Ibu basin, particularly in Sagamu, and this information is highly helpful to hydrologists and engineers in planning for flood regulation and protection measures.Keywords: Ibu River, Hazen Plotting Position, Log-Pearson Type III Distribution, Peaks, Flood Regulation

Ecosystem services and biodiversity conservation under forestation scenarios: options to improve management in the Vez watershed, NW Portugal

Ensuring forest protection and the delivery of forest ecosystem services is a central aim of the European Union’s biodiversity strategy for 2020. Therefore, accurate modelling and mapping of ecosystem services as well as of biodiversity conservation value is an important asset in support of spatial planning and policy implementation. The objectives of this study were to analyse the provision of the multiple ecosystem services under two forestation scenarios (eucalyptus/pine vs. oak) at the watershed scale and to evaluate their possible trade-offs with the biodiversity conservation value. The Vez watershed, in northwest Portugal, was used as case study area, in which soil and water assessment tool (SWAT) was applied to simulate the provision of hydrological services, biomass and carbon storage services. Biodiversity conservation value was based on nature protection regimes and on expert judgement applied to a land cover map. Results indicated large provision of ecosystem services in the high and low mountain sub-basins. The overall performance for water quantity and timing is better under the shrubland and oak forest scenarios, when compared to the eucalyptus/pine forest scenario, which perform better for flood regulation and erosion control services, especially in the low mountain sub-basin. The current shrubland dominated cover also shows good performance for the control of soil erosion. The oak scenario is the one with less trade-offs between forest services and biodiversity conservation. Results highlight SWAT as an effective tool for modelling and mapping ecosystem services generated at the watershed scale, thereby contributing to improve the options for land management.

Mapping technological and biophysical capacities of watersheds to regulate floods

Flood regulation is a widely valued and studied service provided by watersheds. Flood regulation benefits people directly by decreasing the socio-economic costs of flooding and indirectly by its positive impacts on cultural (e.g., fishing) and provisioning (e.g., water supply) ecosystem services. Like other regulating ecosystem services (e.g., pollination, water purification), flood regulation is often enhanced or replaced by technology, but the relative efficacy of natural versus technological features in controlling floods has scarcely been examined. In an effort to assess flood regulation capacity for selected urban watersheds in the southeastern United States, we: (1) used long-term flood records to assess relative influence of technological and biophysical indicators on flood magnitude and duration, (2) compared the widely used runoff curve number (RCN) approach for assessing the biophysical capacity to regulate floods to an alternative approach that acknowledges land cover and soil properties separately, and (3) mapped technological and biophysical flood regulation capacities based on indicator importance-values derived for flood magnitude and duration. We found that watersheds with high biophysical (via the alternative approach) and technological capacities lengthened the duration and lowered the peak of floods. We found the RCN approach yielded results opposite that expected, possibly because it confounds soil and land cover processes, particularly in urban landscapes, while our alternative approach coherently separates these processes. Mapping biophysical (via the alternative approach) and technological capacities revealed great differences among watersheds. Our study improves on previous mapping of flood regulation by (1) incorporating technological capacity, (2) providing high spatial resolution (i.e., 10-m pixel) maps of watershed capacities, and (3) deriving importance-values for selected landscape indicators. By accounting for technology that enhances or replaces natural flood regulation, our approach enables watershed managers to make more informed choices in their flood-control investments.

Shrinking of Dongting Lake and its weakening connection with the Yangtze River: Analysis of the impact on flooding

In this article, the shrinking of Dongting Lake and its progressively weakening connection with the Yangtze River and their impact on flooding before and after the implementation of the Three Gorges Project are analyzed. In recent decades, human activity combined with natural processes has altered the flow of the middle reach channel of the Yangtze River and interfered with its connection with Dongting Lake. This has resulted in progressively more frequent flooding in the area. This study uses hydrological data to analyze the annual maximum discharge and annual maximum stage development of the middle reach of the Yangtze River and Dongting Lake. In recent decades before the Three Gorges Project became operational in 2003, the annual maximum discharge and the maximum stage recorded in the middle reach of the river downstream of Dongting Lake had increased, a result of the weakening of the flood regulation function of Dongting Lake; the annual maximum stage at Luoshan station (downstream, close to the confluence of the Yangtze River and Dongting Lake) had risen by about 2.0m during 1955–2005, (1.5m attributed to annual maximum discharge and 0.5m to river channel deposition). Observational data recorded after the Three Gorges Project was put into operation in 2003, it can be seen that deposition in the Dongting Lake has nearly ceased and the lake׳s connection with the Yangtze River is stable. It is evident that the flood regulation function of Dongting Lake will continue, and that during the lifetime of the Three Gorges Project, the flood situation in the middle reach of the Yangtze River and Dongting Lake will remain stable.