China
Africa
Explore chapters and articles related to this topic
Design tools
Published in G.J.C.M. Hoffmans, H.J. Verheij, Scour Manual, 2021
G.J.C.M. Hoffmans, H.J. Verheij
In the subsiding delta of the Netherlands, high-discharge water levels in embanked rivers are higher than water levels in the surrounding polders. Water then flows to the polders through permeable layers under the dikes. This creates an upward groundwater flow in the polder. Similar effects may occur, for example, at canal dikes or secondary polder dikes. Rainfall may saturate such dikes and cause water to flow out to the canal bottom or the polder water, transporting subsoil material. When this occurs for an elongated period of time, this may endanger the embankment, or the bank protection may slide. A flow of water to the canal may result in bursting of the canal bottom if this bottom consists of a clay lining. This phenomenon can also occur at locks. Therefore, the concrete floor or impermeable bed protection of a lock has to be designed against floating due to upward groundwater flows.
Modelling of extreme precipitation events in risk analysis of water systems
Published in Zhao-Yin Wang, Shi-Xiong Hu, Stochastic Hydraulics 2000, 2020
F. Kuipers, M. Kok, C.J.M. Vermeulen
In this paper we consider a special type of water system: polders. Polders are used for several functions, like housing, industry, nature and agriculture. To optimally fulfil all these functions, a target surface water level is maintained in the polders. Around this target level some deviations have to be tolerated. To prevent the soil from getting too wet (because the farmers cannot then access the land by heavy machinery) often drains or trenches are used to lead ground water to the surface water.
Case Studies
Published in Arnold H. Lobbrecht, Dynamic Water-System Control, 2020
The first case study describes the practical situation in the Delfland area, which includes a large number of polders that drain into a storage basin. Of special interest is the combined functioning of the polders and the storage basin, to satisfy the main interests in the area: flood-prevention, ecology, agriculture, recreation and navigation. Both water-quantity and water-quality aspects play a role in controlling the Delfland water system, depending on the season and the hydrological load.
Quantifying the failure probability of a canal levee
Published in Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2018
K. Lendering, T. Schweckendiek, M. Kok
Polders are often built in river deltas or in low-lying coastal areas to reclaim land. In the Netherlands, a large part of the country consists of polders, but polders are also found in Belgium, New Orleans, Sacramento or Bangkok. Polders typically lie below the surrounding water and are protected from flooding from the main water bodies by flood defences. These flood defences protect polders from the main hazards such as riverine or coastal flooding. Within these polders, large storage and drainage systems are made to drain excess water from the polders to the main water bodies. The drainage canals are aligned by canal levees that protect the surrounding polder from flooding from the inner water (inside the drainage and storage areas).
Evaluation of alternatives to optimize the flood management in the department of Valle del Cauca
Published in Journal of Applied Water Engineering and Research, 2021
Ricardo A. Bocanegra, Jürgen Stamm
Among the environmental problems that can be caused by the polders are the following: obstruction of the natural drainage of the areas located behind the dykes (Kobayashi and Porter 2012), possible affectation of certain species and habitats (Moss and Monstad 2008), modification of the natural storage of volumes of water that occurs in the floodplains (Moss and Monstad 2008; Kobayashi and Porter 2012) and possible reduction of the concentration of oxygen when water is stored for a long time (Forster and Bronstert 2009).