Civil Engineering Pt 9

The Delta Works

The American Society of Civil Engineers has ranked 'The Delta Works' as one of the seven wonders of the modern world.

The American Society of Civil Engineers is a tax-exempt professional body founded in 1852 to represent worldwide members of the civil engineering profession. Headquartered in Reston, Virginia, it is the oldest national engineering society in the United States.

Executive Summary

In 1953, catastrophic flooding, resulting in over 8,000 deaths, made the Netherlands' vulnerability to ocean storm surges tragically clear. The solution: a massive infrastructural project called the Delta Works.

This system of dams, dykes, levees, locks and other components enables the modulation of tides flowing in and out of the country's numerous estuaries. In addition, the works opened some 900 square miles (2,330 km2) of dry land. They have also secured freshwater sources against seawater inundation and provided new bridge and highway routes to island communities.

Engineers constructed the Delta Plan over forty-three years 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.

History

The estuaries of the rivers Rhine, Meuse and Schelde, have been flooding over the centuries. After building the Afsluitdijk (1927 – 1932), the Dutch started studying the damming of the Rhine-Meuse Delta.

Dutch Engineers developed plans to shorten the coastline and turn the delta into freshwater coastal lakes.

In 1950 two small estuary mouths, the Brielse Gat near Brielle and the Botlek near Vlaardingen, were dammed.

After the North Sea flood of 1953, measures were put in place to prevent such disasters in future. They revised some of the old plans and came up with the "Delta Plan".

In response to public pressure, the Delta Plan changed. For example, in the Nieuwe Waterweg, the heightening and the associated widening of the dikes proved very difficult because of public opposition to the planned destruction of significant historic buildings.

The storm surge barrier closes only when the sea level will rise 3 metres above mean sea level. Under normal conditions, the estuary's mouth is open, and saltwater flows in and out with the tide. Strengthening weak dikes was carried out.

Environmental policy implementations

In an attempt to restore and preserve the natural system surrounded by the dykes and storm-surge barrier, the concept 'building with nature' was introduced in revised Delta Program updates after 2008. The new integrated water management plan considers protection against flooding and covers water quality, leisure industry, economic activities, shipping, environment, and nature.

Environmental effects

Although awareness for the environment grew, the Delta Project has caused numerously irreversible effects on the environment in the past. Blocking the estuary mouths did reduce the length of dykes that otherwise would have to be built to protect against floods, but it also led to significant changes in the water systems. For example, the tides disappeared, which resulted in a less smooth transition from seawater into freshwater. Flora and fauna suffered from this noticeable change. In addition, rivers got covered up by polluted sludge since there was no longer an open passage to the sea.

Current status

The Europoortkering completed the original plan

The Delta Plan was officially declared finished after forty-three years in 1997.

Climate change and rising sea levels will mean that the dikes will eventually have to be made higher and broader.

In September 2008, the Delta Commission said there would be the need for a massive new building program to strengthen the country's water defences against the anticipated effects of global warming for the next 190 years.

The plans included drawing up worst-case scenarios for evacuations. Furthermore, they had more than €100 billion, or $144 billion, in new spending through the year 2100 for measures, such as broadening coastal dunes and strengthening sea and river dikes. In addition, the commission said the country must plan for a rise in the North Sea of 1.3 meters by 2100 and 4 meters by 2200.

Credits attributed to The American Society of Civil Engineers

Wikipedia https://en.wikipedia.org/wiki/Delta_Works