China
Africa
Explore chapters and articles related to this topic
Urban stormwater planning
Published in James C. Y. Guo, Urban Flood Mitigation and Stormwater Management, 2017
Land development projects tend to achieve high density in land uses utilizing the most economic measures. Thus, floodplains become valuable if the low land areas can be reclaimed for development. The purpose of floodplain management is to provide guidance, conditions, and restrictions for development in floodplain areas while protecting the public’s health, safety, welfare, and property from danger and damage. To provide impetus for proper floodplain management, the US government, acting through the Federal Emergency Management Agency’s National Flood Insurance Program (FEMA NFIP), has established regulations for development in floodplain areas. Compliance with these regulations allows property owners to obtain lower cost flood insurance premiums and/or eliminates the requirement for the owner to obtain flood insurance as a condition for obtaining government-supported loans. FEMA has adopted the 100-year flood (1% chance of annual occurrence) as the base flood for floodplain management purposes and delineates the 100-year floodplain on their maps. For certain stream courses studied by FEMA by detailed methods, a floodway may also be depicted. The floodway is a portion of the floodplain and is defined as the channel itself plus any adjacent land areas that must be kept free from encroachment in order to pass the base flood without increasing water surface elevations by more than a designated height such as 1 ft in rural areas or 6 in. in urban areas.
The Ecological Significance to Fisheries of Bottomland Hardwood Systems: Values, Detrimental Impacts, and Assessment: The Report of the Fisheries Workgroup
Published in James G. Gosselink, Lyndon C. Lee, Thomas A. Muir, Ecological Processes and Cumulative Impacts, 2020
H. Dale Hall, Victor W. Lambou, Paul Adamus, James Brown, C. Fred Bryan, Ellis Clairain, Fred Dunham, Gerry Horak, Joseph Jacob, Richard Johnson, Albert Korgi, William Kruczynski, Edward Smith
Flood-control projects offer a degree of floodplain protection locally, increase flood problems downstream, and induce additional flood-control measures to control the downstream problems. Through this process, an expectation is spawned and cultivated among the public that flood protection will be provided simply because it was provided upstream. This expectation, in addition to federal financial subsidies, encourages landowners to convert valuable bottomland hardwood wetlands to farmland. When crop damage occurs as a result of flooding, levee construction, channelization, or upstream impoundments, additional flood protection measures are demanded. A technique for illustrating this contention is to use a basin case history.
Impact of Urbanization on Flooding
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
A floodplain is flat land along a stream or river that is periodically flooded. Historically, many towns have been built on floodplains due to access to fresh water; the fertility for farming; cheap transportation through the waterway; and ease of development of flat land. However, flood damage has become the worst natural disaster in history; for example, the 1931 China Yellow River floods are estimated to have killed millions. Development along rivers and floodplains in urban areas has increased the floods dramatically in floodplains. The effect of urbanization on the floodplain will be summarized. Meanwhile, flood reduction approaches will be introduced for better planning, design, and management in floodplains.
Optimized expressions to evaluate the flow discharge in main channels and floodplains using evolutionary computing and model classification
Published in International Journal of River Basin Management, 2018
Abdolreza Zahiri, Mohammad Najafzadeh
In overbank flows, the river system not only behaves as a conveyance but also as a storage or pond. It is recognized that for sediment transport, only the flow discharge in main channel is effective and floodplain’s discharge has a negligible impact upon the subject. There is no disguising the fact that the flow velocity in the floodplains is considerably less than the main channel and it is inadequate to cause major movement of suspended sediments. In fact the floodplains, due to their high capacities, play a prominent role in flood water level reduction, water retention and sediment deposition. These features are essential for wetlands restoration and preserve of river ecology as well as for success of flood mitigation works. Determination of the main channel and floodplains discharges covers the main input data for several hydraulic and morphologic computations such as pollutant dispersion and bed shear stress distribution in river compound channels.
Expanding the horizons of integrated flood risk management: a critical analysis from an Irish perspective
Published in International Journal of River Basin Management, 2018
More specifically, each member state is required to implement the Floods Directive over a specified timescale (see Table 1). The Directive requires, in summary, a preliminary flood risk assessment to identify areas of significant risk, and, for areas identified as being at significant risk, flood hazard and flood risk maps must be produced for various probability-based events. Finally, FRMPs must be drawn up for these flood probability zones. These plans must take into account flood extent, and how flood waters interact with the existing (or where beneficial, with restored) landscape and habitats, and consider land-use practices, options of controlled flooding and the role of water-dependent infrastructures. They are required to consider the characteristics of each river basin and consider such measures as: avoiding development on floodplains or adapting development to flood risks (i.e. prevention);floodplain restoration (i.e. protection);awareness raising and communication of roles and responsibilities in an emergency (i.e. preparedness);integration of flood forecasts and early warning services (SEC 2006b, CEC 2007).
New formulas addressing flow resistance of floodplain vegetation from emergent to submerged conditions
Published in International Journal of River Basin Management, 2022
Walter Box, Juha Järvelä, Kaisa Västilä
Floodplain vegetation provides habitat, stabilizes riverbed and banks and improves water quality by trapping sediment, nutrients and pollutants (Vargas-Luna et al., 2015; Västilä & Järvelä, 2018). For ecological considerations, vegetation is increasingly used as a nature-based solution (NBS) in river engineering and management (Rowiński et al., 2018; Vargas-Luna et al., 2018). From flood management viewpoint, vegetation increases flow resistance and reduces the flow conveyance capacity of the channel (Luhar & Nepf, 2013; Rubol et al., 2018; Stone et al., 2013; Yang et al., 2007).