What is Flood Water Management? Why does it flood? What are its causes? How are floods controlled? What are the techniques? Why does the Netherlands have the world’s best flood control management techniques? What are the flood water management strategies made?
The floods are responsible for the death of almost twice the amount of people as tornadoes and hurricanes put together. According to UNESCO, the global average of economic losses caused by floods and droughts is more than US$ 40 billion a year in all economic sectors.
By 2017, natural disasters related to water caused worldwide losses of $ 306 billion. Between 1980 and 2016, 90% of disasters are climate related. In 2016, of global losses, 31% were due to storms, 32% attributed to flooding and 10% to extreme temperatures.
Flood causes
* Periodic flooding occurs in many rivers, forming a surrounding region known as an alluvial plain, either by heavy rains or snow melting
* Rapid flooding, with little or no advance warning, is called sudden floods usually resulting from heavy rains in a relatively small area, or if the area was already saturated with previous precipitation. Sometimes combined with failure of dams, elevation of retention pond levels or other structures that contain water.
* Coastal areas are flooded by unusually high tides or series of waves such as storm flood or Tsunami , or composed of strong winds and storms such as hurricanes or tornadoes.
* Climate change may contribute to increased flooding resulting from rising sea levels and heavy rains in certain regions of the planet.
* Or low altitude problems such as in the Netherlands
Flood water control
* Methods used to reduce or prevent the damaging effects of flood waters. Some of the common techniques used for flood control are the installation of rock beams, rock rip-raps, sand bags, maintenance of normal slopes with vegetation or application of soil cements on steeper slopes and construction or expansion of drainage.
* Other methods include dykes, dams, retention detention basins or polders.
Why does the Netherlands have the best flood water management techniques?
The Netherlands has the world’s best flood management technique. Due to which the Netherlands is illustrated by the saying “God created the world, but the Dutch created the Netherlands”
Over the centuries, the Netherlands had frequently been flooding, from the rivers as well as the sea in varying degrees and severity. So the Dutch have built various structures to defend against flooding dating from the 1700 century.
Netherlands due to its low elevation, approximately two thirds of its area is below sea level. Therefore it’s more vulnerable to flooding, while the country is densely populated. The lowest point is Zuidplaspolder (Nieuwerkerk aan den IJssel) −7 m (−23 ft), below sea level. Hence Flood control is an important issue for the Netherlands.
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 (historically: windmills) keep the low-lying parts dry for habitation and agriculture.
18,000 square kilometers (6,800 sq mi)was reclaimed from the sea and protected by modern flood management techniques. Water boards in the Netherlands hold separate elections, levy taxes, and function independently from other government bodies.
After the occurrence of catastrophes in the past centuries. The Dutch have made the major flood management projects that were constructed in the Netherlands: the Zuiderzee Works and the Delta Works.
What were the flood water management strategies made?
The Delta Works: It is the world’s largest flood protection system consisting of 13 sections construction projects in the southwest of the Netherlands to protect a large area of land around the Rhine–Meuse–Scheldt delta from the sea. Delta works has 16,500km of dams. This imposing project, also referred to as one of the seven wonders of the world.
The purpose of the Delta Works:
* To increase the safety norms tenfold and strengthen dikes accordingly,
* To use sand replenishment to broaden the North Sea coast and allow it to grow naturally,
* To use the lakes in the southwest river delta as river water retention basins or polders,
* To raise the water level in the IJsselmeer to provide freshwater.
Zuiderzee Works: Its is a man-made system of dams and dikes, land reclamation and water drainage work, in total the largest hydraulic engineering project undertaken by the Netherlands 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. About 20% of land in the Netherlands is claimed this way.
The purpose of the zuiderzee project:
* To retain land which could be used for agriculture in turn increase economy
* To protect further flooding from North sea
* To fill up with fresh water instead of sea water, thereby improving water management
As a whole, the combination of the Delta Works and Zuiderzee Works is considered to be one of the seven wonders of the modern world.
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What are Dykes and polders?
Dykes are man-made structures that defend against natural forces like water, climate and altitude and are mostly constructed of material found on site. The Netherlands’ dike network extends for over 22,000 kilometers (including dikes that do not serve as flood defenses), while the Dutch coastline measures a mere 880 kilometers.
Polders is a low-lying tract of land that forms an artificial hydrological entity such as a lake or the seabed when enclosed by dykes. This is the Land reclaimed from a body of water which is pumped out or drained by opening sluices at low tide. The land thus claimed turns into marshes .The ground level in drained marshes subsides over time. Water enters the low-lying polder through infiltration and water pressure of groundwater, or rainfall, or transport of water by rivers and canals.
Although the Netherlands is well protected from the water by the dike defense system today, there is always a risk of flooding. Therefore the Netherlands is frequently associated with polders, resulting in some 3,000 polders being set up to maintain the integrity of the water defenses around polders, maintain the waterways inside a polder, and control the various water levels inside and outside the polder.
What are the practices for Coastline flood water management systems to prevent flooding?
Sand nourishments
Sand nourishments are the mechanical placement of sand in the coastal zone to advance the shoreline or to maintain the volume of sand in the littoral system.t is a measure to stabilize the shoreline and support the flood or erosion protection function of the coast. It maintains the historical landscape of the coastline, while hard measures (seawalls, breakwaters, etc.) may change the coastline significantly.
Also, sand nourishment may increase the recreational value of the beach and dunes. Since sand nourishment keeps natural gradients (wet-dry, salt-fresh, shallow-deep) intact, the coastal ecosystem will benefit. Besides marine coastal areas, sand nourishments are also applied on lake coasts.
Dumping sand
To protect the Netherlands’ natural beaches from unrelenting erosion. Every year, the Dutch government shells out millions of dollars to dump sand on receding beaches, shoring them up against an ever-encroaching sea. But that method is expensive, and requires constant upkeep.
In modern times, in the Netherlands flood disasters coupled with technological developments have led to large construction works to reduce the influence of the sea and prevent future floods. These have proved essential over the course of Dutch history, both geographically and militarily, and have greatly impacted the lives of many living in the cities affected, stimulating their economies through constant infrastructural improvement.
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