A levee, dike, dyke, embankment, floodbank, or stop bank is a structure used to keep the course of rivers from changing and to protect against flooding of the area adjoining the river or coast. It is usually earthen and often runs parallel to the course of a river in its floodplain or along low-lying coastlines.
A polder is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The three types of polder are:
- Land reclaimed from a body of water, such as a lake or the seabed
- Flood plains separated from the sea or river by a dike
- Marshes separated from the surrounding water by a dike and subsequently drained; these are also known as koogs, especially in Germany
A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrology and are of significant concern in agriculture, civil engineering and public health. Human changes to the environment often increase the intensity and frequency of flooding, for example land use changes such as deforestation and removal of wetlands, changes in waterway course or flood controls such as with levees, and larger environmental issues such as climate change and sea level rise. In particular climate change's increased rainfall and extreme weather events increases the severity of other causes for flooding, resulting in more intense floods and increased flood risk.
The Zuiderzee or Zuider Zee was a shallow bay of the North Sea in the northwest of the Netherlands, extending about 100 km inland and at most 50 km wide, with an overall depth of about 4 to 5 metres (13–16 feet) and a coastline of about 300 km. It covered 5,000 km2 (1,900 sq mi). Its name is Dutch for "southern sea", indicating that the name originates in Friesland, to the north of the Zuiderzee.
The Wadden Sea is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern continental Europe and the range of low-lying Frisian Islands, forming a shallow body of water with tidal flats and wetlands. It has a high biological diversity and is an important area for both breeding and migrating birds. In 2009, the Dutch and German parts of the Wadden Sea were inscribed on UNESCO's World Heritage List and the Danish part was added in June 2014.
The Zuiderzee Works is a system of dams and dikes, land reclamation and water drainage work, which was the largest hydraulic engineering project undertaken by the Netherlands during the twentieth century. The project involved the damming of the Zuiderzee, a large, shallow inlet of the North Sea, and the reclamation of land in the newly enclosed water using polders. Its main purposes are to improve flood protection and create additional land for agriculture.
The Delta Works is a series of construction projects in the southwest of the Netherlands to protect a large area of land around the Rhine–Meuse–Scheldt delta from the sea. Constructed between 1954 and 1997, the works consist of dams, sluices, locks, dykes, levees, and storm surge barriers located in the provinces of South Holland and Zeeland.
The 1953 North Sea flood was a major flood caused by a heavy storm surge that struck the Netherlands, north-west Belgium, England and Scotland. Most sea defences facing the surge were overwhelmed, resulting in extensive flooding.
A levee breach or levee failure is a situation where a levee fails or is intentionally breached, causing the previously contained water to flood the land behind the levee.
The Burchardi flood was a storm tide that struck the North Sea coast of North Frisia, Dithmarschen and southwest Jutland on the night between 11 and 12 October 1634. Overrunning dikes, it shattered the coastline and caused thousands of deaths and catastrophic material damage. Much of the island of Strand washed away, forming the islands Nordstrand, Pellworm and several halligen.
Coastal management is defence against flooding and erosion, and techniques that stop erosion to claim lands. Protection against rising sea levels in the 21st century is crucial, as sea level rise accelerates due to climate change. Changes in sea level damage beaches and coastal systems are expected to rise at an increasing rate, causing coastal sediments to be disturbed by tidal energy.
Flood control is an important issue for the Netherlands, as due to its low elevation, approximately two thirds of its area is vulnerable to flooding, while the country is densely populated. Natural sand dunes and constructed dikes, dams, and floodgates provide defense against storm surges from the sea. River dikes prevent flooding from water flowing into the country by the major rivers Rhine and Meuse, while a complicated system of drainage ditches, canals, and pumping stations keep the low-lying parts dry for habitation and agriculture. Water control boards are the independent local government bodies responsible for maintaining this system.
In the Netherlands, a water board, water council or water authority is a regional governing body solely charged with the management of surface water in the environment. Water boards are independent of administrative governing bodies like provinces and municipalities. In general, they are responsible for managing rivers and canals, issues with the flow of watercourses and drainage issues, water collection, flood and erosion prevention and provision of potable water. They manage polder systems, water levels, water barriers and locks, enforcements, water quality and sewage treatment in their respective regions. The concept of a coordinating "High Water Authority" (Hoogheemraadschap) originated in what now is the province of South Holland in the 12th century.
Flood control methods are used to reduce or prevent the detrimental effects of flood waters. Flood relief methods are used to reduce the effects of flood waters or high water levels. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. A distinction is made between structural and non-structural flood control measures. Structural methods physically restrain the flood waters, whereas non-structural methods do not. Building hard infrastructure to prevent flooding, such as flood walls, is effective at managing flooding. However, increased best practice within landscape engineering is to rely more on soft infrastructure and natural systems, such as marshes and flood plains, for handling the increase in water. To prevent or manage coastal flooding, coastal management practices have to handle natural processes like tides but also the human-caused sea level rise.
Coastal flooding occurs when dry and low-lying land is submerged (flooded) by seawater. The range of a coastal flooding is a result of the elevation of floodwater that penetrates the inland which is controlled by the topography of the coastal land exposed to flooding. The seawater can flood the land via several different paths: direct flooding, overtopping of a barrier, or breaching of a barrier. Coastal flooding is largely a natural event. Due to the effects of climate change and an increase in the population living in coastal areas, the damage caused by coastal flood events has intensified and more people are being affected.
Giant Sea Wall Jakarta is part of a massive coastal development project in Jakarta, Indonesia which commenced in 2014 and expected to be materialized by 2027. The coastal development project includes the construction of a giant seawall along the coast, building a water reservoir, and the reclamation of land. Construction of an 8 km part of the sea wall along the coast was officially launched on Oct. 9, 2014.
The Inundation of Walcheren was the intentional, but uncontrolled military inundation, effected by bombing the sea dikes of the former island of Walcheren in Zeeland by the Allies on and after 3 October 1944 in the context of Operation Infatuate during the Battle of the Scheldt after the Allied Invasion of Normandy during World War II. Though the inundation was justified by military necessity, it is controversial whether it was proportional in view of the predictable devastating effects for the civilian population, and the ecology of the island. The fact that the breaches in the sea dikes of the island remained open for a very long time, subjecting the island to the full impact of the twice-daily tides, caused severe damage to agricultural land and infrastructure, and severe hardship for the civilian population. Leaving the breaches open for such a long time, which was unavoidable due to the war-time lack of resources making closing impossible, subjected them to scouring by the tides, that widened and deepened them to such an extent that closing them eventually became extremely difficult, necessitating the development of new dike-building techniques, such as the use of caissons. The last breach was closed on 23 October 1945 and the draining of the island took until early 1946. Only after that could rebuilding the infrastructure and reconstructing the housing stock and the island's economy start. Walcheren was spared during the North Sea Flood of 1953 that devastated many other parts of Zeeland.
Sinking cities are urban environments that are in danger of disappearing due to their rapidly changing landscapes. The largest contributors to these cities becoming unlivable are the combined effects of climate change, land subsidence, and accelerated urbanization. Many of the world's largest and most rapidly growing cities are located along rivers and coasts, exposing them to natural disasters. As countries continue to invest people, assets, and infrastructure into these cities, the loss potential in these areas also increases. Sinking cities must overcome substantial barriers to properly prepare for today's dynamic environmental climate.
Sedimentation enhancing strategies are environmental management projects aiming to restore and facilitate land-building processes in deltas. Sediment availability and deposition are important because deltas naturally subside and therefore need sediment accumulation to maintain their elevation, particularly considering increasing rates of sea-level rise. Sedimentation enhancing strategies aim to increase sedimentation on the delta plain primarily by restoring the exchange of water and sediments between rivers and low-lying delta plains. Sedimentation enhancing strategies can be applied to encourage land elevation gain to offset sea-level rise. Interest in sedimentation enhancing strategies has recently increased due to their ability to raise land elevation, which is important for the long-term sustainability of deltas.
Pieter Jacobus (P.J.) Wemelsfelder was a prominent Dutch hydraulic engineer who made significant contributions to the field of hydrometry in the Netherlands, and in hydraulic engineering internationally. In addition to his involvement in the design and planning of the Delta Works, he published widely and is notable for the first use of probability theory in the design of flood levels.
![A typical sleeper dike near the Hondsbossche Zeewering [nl]. In 1570, this dike prevented the flooding of North Holland during the All Saints' Flood (1570) after the breakthrough of the Hondsbossche Zeewering. SlaperdijkHondsbossche.jpg](http://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/SlaperdijkHondsbossche.jpg/220px-SlaperdijkHondsbossche.jpg)