Connectivity of floodplains in Germany – which floodplain extent is relevant?

2021 ◽  
Author(s):  
Stephanie Natho
Keyword(s):  
Urban Areas ◽  
Flood Hazard ◽  
Arable Land ◽  
Natura 2000 ◽  
Climate Mitigation ◽  
Flood Magnitude ◽  
Inundation Extent ◽  
Original Size ◽  
Holding Back ◽  
Water Nutrients

<p>Floodplains are transitional ecosystems, rich in biodiversity, endangered and adapted to inundation by floods. Flood magnitude, hydrologic connectivity and elevation define the extent of an active floodplain. In past centuries, active floodplains in Germany were reduced by up to 90% of their original size – in terms of the area that is statistically inundated at least once every 100 years. But, does this area reflect the area relevant for floodplain ecosystems and for evaluating their functioning and the services they provide? Analyzing two scenarios of Flood Hazard Maps (FHM), a German-wide comparison including 78 rivers was carried out to quantify the extent of floods with statistical occurrence intervals of 5 to 25 years, so-called ‘frequent floods’ (T-frequent), and intervals of 100 years, or ‘medium floods’ (T-medium), as well as selected characteristics. The comparison was carried out on the river (basin) level, and based on hydrological catchments. By additionally analyzing measured discharges of relevant gauges from the past 20 years, real inundation was quantified. As a result, even in exceptional wet years these ‘frequent floods’ occur for a few days per year or not at all. The extent of the two FHM scenarios differs for most areas: Only at 13% of gauging units was the T-frequent inundation extent similar to that of T-medium. Furthermore, within T-medium the land use of arable land doubles and that of urban areas more than doubles, showing how disconnected the T-medium floodplain is in many parts. On the other hand, 25% of grasslands are Natura 2000 meadows occurring within the borders of T-frequent but only 6% are Natura 2000 meadows outside these borders, indicating the effect of connectivity and thus inundation, making these habitats valuable in terms of biodiversity mainly in T-frequent. This study provides evidence that, especially for regulatory services like water purification, water retention and climate mitigation, T-frequent might be more suitable for consideration. With more frequent flooding, less intensively used areas are connected more often, holding back water, nutrients and sediments – in addition to comparatively more areas relevant for nature conservation. For flood protection and also as a refuge for flora and fauna and for connection of habitats, of course the extent of disastrous 100-yr floods are important.</p>

scholarly journals Urban Flood Modeling Using 2D Shallow-Water Equations in Ouagadougou, Burkina Faso

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2120
Author(s):  
Gnenakantanhan Coulibaly ◽  
Babacar Leye ◽  
Fowe Tazen ◽  
Lawani Adjadi Mounirou ◽  
Harouna Karambiri
Keyword(s):  
Shallow Water ◽  
Shallow Water Equations ◽  
Urban Areas ◽  
Flood Hazard ◽  
Scientific Information ◽  
Roughness Coefficient ◽  
Flood Events ◽  
African Countries ◽  
Numerical Tool ◽  
2D Shallow Water Equations

Appropriate methods and tools accessibility for bi-dimensional flow simulation leads to their weak use for floods assessment and forecasting in West African countries, particularly in urban areas where huge losses of life and property are recorded. To mitigate flood risks or to elaborate flood adaptation strategies, there is a need for scientific information on flood events. This paper focuses on a numerical tool developed for urban inundation extent simulation due to extreme tropical rainfall in Ouagadougou city. Two-dimensional (2D) shallow-water equations are solved using a finite volume method with a Harten, Lax, Van Leer (HLL) numerical fluxes approach. The Digital Elevation Model provided by NASA’s Shuttle Radar Topography Mission (SRTM) was used as the main input of the model. The results have shown the capability of the numerical tool developed to simulate flow depths in natural watercourses. The sensitivity of the model to rainfall intensity and soil roughness coefficient was highlighted through flood spatial extent and water depth at the outlet of the watershed. The performance of the model was assessed through the simulation of two flood events, with satisfactory values of the Nash–Sutcliffe criterion of 0.61 and 0.69. The study is expected to be useful for flood managers and decision makers in assessing flood hazard and vulnerability.

scholarly journals Safer_RAIN: a Fast-Processing DEM-Based Algorithm for Pluvial Flood Hazard Assessment Across Large Urban Areas

2019 ◽  
Author(s):  
Attilio Castellarin ◽  
Caterina Samela ◽  
Simone Persiano ◽  
Stefano Bagli ◽  
Valerio Luzzi ◽  
...  
Keyword(s):  
Hazard Assessment ◽  
Urban Areas ◽  
Flood Hazard ◽  
Flood Hazard Assessment ◽  
Fast Processing

The Persistence of Subsistence and the Limits to Development Studies: The Challenge of Tanzania

Africa ◽  
2000 ◽  
Vol 70 (4) ◽  
pp. 614-652 ◽  
Author(s):  
Tony Waters
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Third World ◽  
Industrial Revolution ◽  
System Development ◽  
Arable Land ◽  
World System ◽  
Development Studies ◽  
Capitalist System ◽  
Rural Tanzania

AbstractThere are two general approaches to assessing what is known as ‘development’. First, there are classical accounts focusing on Europe's development during the industrial revolution. They describe how urban areas expanded at the expense of the social and economic resources of the rural areas, disrupting an independent subsistence peasantry. A major consequence is that today all Europeans are dependent socially, politically, and economically on the modern capitalist system. The second (more common) approach to development focuses on the modern Third World. This approach assumes that, as with Europe, the entire Third World is dependent on the modern capitalist system. Development studies focus on the assessment of how Third World countries can most effectively engage world capitalism. Discussion is typically reduced to comparisons between world systems theory and neoclassical economics. The Tanzanian government has used standard policies grounded in neoclassical and world‐system assumptions since independence. But both policies failed to produce the predicted economic growth. This article argues that both policies failed because the Tanzanian peasantry, like the early modern European peasantry, is not dependent on the operation of world capitalism for basic subsistence. In fact, as studies have shown, rural Tanzania is only weakly incorporated into the capitalist world system, and in consequence has not been an easy target for what world‐system theorists call ‘peripheral integration’. What makes Tanzania different is the fact that the rural peasantry do not use market mechanisms in the distribution of the ‘means of production’, especially arable land for swidden agriculture, or, for that matter, labour or cattle.

scholarly journals The Assessment of Level of Flash Floods Threat of Urbanised Areas

2017 ◽  
Vol 65 (2) ◽  
pp. 519-526 ◽  
Author(s):  
Pavla Štěpánková ◽  
Miroslav Dumbrovský ◽  
Karel Drbal
Keyword(s):  
Czech Republic ◽  
Urban Areas ◽  
Flood Hazard ◽  
Flash Floods ◽  
Flood Risk Assessment ◽  
Entire Area ◽  
The Czech Republic ◽  
Eu Directive ◽  
Run Off ◽  
Technical Measures

Flash floods (or torrential rain flooding) is another type of flood hazard which has caused casualties and significant property damages. A methodology for identification of urban areas, which can potentially be burdened by that type of flood hazard, was proposed. This method, also called Method of Critical Points (CP), is a repeatable process able to identify areas, which are significant in terms of formation of surface run‑off and erosion. As addition to the preliminary flood risk assessment according to EU Directive 2007/60/ES on the Assessment and Management of Flood Risks, the presented methodology was applied for the entire area of the Czech Republic and the results are being used for the updating of non‑technical measures, e.g. urban planning. In the article, the principles of methodology of CP are described and results of the first application in the Czech Republic are presented, as well as possible interpretations of them.

scholarly journals Combined fluvial and pluvial urban flood hazard analysis: method development and application to Can Tho City, Mekong Delta, Vietnam

2015 ◽  
Vol 3 (8) ◽  
pp. 4967-5013 ◽  
Author(s):  
H. Apel ◽  
O. M. Trepat ◽  
N. N. Hung ◽  
D. T. Chinh ◽  
B. Merz ◽  
...  
Keyword(s):  
Hydrodynamic Model ◽  
Urban Areas ◽  
Large Scale ◽  
Method Development ◽  
Flood Hazard ◽  
Hazard Analysis ◽  
Mekong Delta ◽  
Rain Gauge ◽  
Convective Precipitation ◽  
Can Tho City

Abstract. Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas, and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either fluvial or pluvial flood hazard, studies of combined fluvial and pluvial flood hazard are hardly available. Thus this study aims at the analysis of fluvial and pluvial flood hazard individually, but also at developing a method for the analysis of combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as example. In this tropical environment the annual monsoon triggered floods of the Mekong River can coincide with heavy local convective precipitation events causing both fluvial and pluvial flooding at the same time. Fluvial flood hazard was estimated with a copula based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. Pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data, and a stochastic rain storm generator. Inundation was simulated by a 2-dimensional hydrodynamic model implemented on a Graphical Processor Unit (GPU) for time-efficient flood propagation modelling. All hazards – fluvial, pluvial and combined – were accompanied by an uncertainty estimation considering the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by percentile maps. The results are critically discussed and ways for their usage in flood risk management are outlined.

Assessment of flood hazard mapping in urban areas using entropy weighting method: a case study in Hamadan city, Iran

2019 ◽  
Vol 67 (5) ◽  
pp. 1435-1449 ◽  
Author(s):  
Mehdi Sepehri ◽  
Hossein Malekinezhad ◽  
Seyed Zeynalabedin Hosseini ◽  
Ali Reza Ildoromi
Keyword(s):  
Urban Areas ◽  
Flood Hazard ◽  
Hazard Mapping ◽  
Weighting Method

scholarly journals Abandoned Farmland Location in Areas Affected by Rapid Urbanization Using Textural Characterization of High Resolution Aerial Imagery

2020 ◽  
Vol 9 (4) ◽  
pp. 191 ◽  
Author(s):  
Juan José Ruiz-Lendínez
Keyword(s):  
Urban Areas ◽  
Spatial Information ◽  
Arable Land ◽  
Aerial Imagery ◽  
Rapid Urbanization ◽  
Abandoned Farmland ◽  
Textural Characterization ◽  
Study Results ◽  
Abandoned Land ◽  
The City

Several studies have demonstrated that farmland abandonment occurs not only in rural areas, but is also closely interlinked with urbanization processes. Therefore, the location of abandoned land and the registration of the spatial information referring to it play important roles in urban land management. However, mapping abandoned land or land in the process of abandonment is not an easy task because the limits between the different land uses are not clear and precise. It is therefore necessary to develop methods that allow estimating and mapping this type of land as accurately as possible. As an alternative to other geomatics methods such as satellite remote sensing, our approach proposes a framework for automatically locating abandoned farmland in urban landscapes using the textural characterization and segmentation of aerial imagery. Using the city of Poznań (Poland) as a case study, results demonstrated the feasibility of applying our approach, reducing processing time and workforce resources. Specifically and by comparing the results obtained with the data provided by CORINE Land Cover, 2275 ha (40.3%) of arable land within the city limits were abandoned, and the area of abandoned arable land was almost 9.2% of the city’s area. Finally, the reliability of the proposed methodology was assessed from two different focuses: (i) the accuracy of the segmentation results (from a positional point of view) and (ii) the efficiency of locating abandoned land (as a specific type of land use) in urban areas particularly affected by rapid urbanization.

scholarly journals Evaluating the impact of model complexity on flood wave propagation and inundation extent with a hydrologic–hydrodynamic model coupling framework

2019 ◽  
Vol 19 (8) ◽  
pp. 1723-1735 ◽  
Author(s):  
Jannis M. Hoch ◽  
Dirk Eilander ◽  
Hiroaki Ikeuchi ◽  
Fedor Baart ◽  
Hessel C. Winsemius
Keyword(s):  
Flood Risk ◽  
Management Practices ◽  
Flood Hazard ◽  
Hydrologic Model ◽  
Model Complexity ◽  
Model Coupling ◽  
Coupled Models ◽  
Flood Simulations ◽  
Inundation Extent ◽  
The Impact

Abstract. Fluvial flood events are a major threat to people and infrastructure. Typically, flood hazard is driven by hydrologic or river routing and floodplain flow processes. Since they are often simulated by different models, coupling these models may be a viable way to increase the integration of different physical drivers of simulated inundation estimates. To facilitate coupling different models and integrating across flood hazard processes, we here present GLOFRIM 2.0, a globally applicable framework for integrated hydrologic–hydrodynamic modelling. We then tested the hypothesis that smart model coupling can advance inundation modelling in the Amazon and Ganges basins. By means of GLOFRIM, we coupled the global hydrologic model PCR-GLOBWB with the hydrodynamic models CaMa-Flood and LISFLOOD-FP. Results show that replacing the kinematic wave approximation of the hydrologic model with the local inertia equation of CaMa-Flood greatly enhances accuracy of peak discharge simulations as expressed by an increase in the Nash–Sutcliffe efficiency (NSE) from 0.48 to 0.71. Flood maps obtained with LISFLOOD-FP improved representation of observed flood extent (critical success index C=0.46), compared to downscaled products of PCR-GLOBWB and CaMa-Flood (C=0.30 and C=0.25, respectively). Results confirm that model coupling can indeed be a viable way forward towards more integrated flood simulations. However, results also suggest that the accuracy of coupled models still largely depends on the model forcing. Hence, further efforts must be undertaken to improve the magnitude and timing of simulated runoff. In addition, flood risk is, particularly in delta areas, driven by coastal processes. A more holistic representation of flood processes in delta areas, for example by incorporating a tide and surge model, must therefore be a next development step of GLOFRIM, making even more physically robust estimates possible for adequate flood risk management practices.

scholarly journals Protected Cropping in Warm Climates: A Review of Humidity Control and Cooling Methods

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2737 ◽  
Author(s):  
Barkat Rabbi ◽  
Zhong-Hua Chen ◽  
Subbu Sethuvenkatraman
Keyword(s):  
Urban Areas ◽  
Arable Land ◽  
Climatic Conditions ◽  
Future Research ◽  
Conventional Farming ◽  
Crop Species ◽  
Humidity Control ◽  
Tropical Regions ◽  
Cooling Methods ◽  
Warm Climates

The projected increase of the world’s population, coupled with the shrinking area of arable land required to meet future food demands, is building pressure on Earth’s finite agricultural resources. As an alternative to conventional farming methods, crops can be grown in protected environments, such as traditional greenhouses or the more modern plant factories. These are usually more productive and use resources more efficiently than conventional farming and are now receiving much attention—especially in urban and peri-urban areas. Traditionally, protected cropping has been predominantly practised in temperate climates, but interest is rapidly rising in hot, arid areas and humid, tropical regions. However, maintaining suitable climatic conditions inside protected cropping structures in warm climates—where warm is defined as equivalent to climatic conditions that require cooling—is challenging and requires different approaches from those used in temperate conditions. In this paper, we review the benefits of protected cropping in warm climates, as well as the technologies available for maintaining a controlled growing environment in these regions. In addition to providing a summary of active cooling methods, this study summarises photovoltaic (PV)-based shading methods used for passive cooling of greenhouses. Additionally, we also summarise the current humidity-control techniques used in the protected cropping industry and identify future research opportunities in this area. The review includes a list of optimum growing conditions for a range of crop species suited to protected cropping in warm climates.

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