Rietveld - Wandeling Delftse Waterweg

The lowest part of Delft's old inner city
In the Rietveld (and also the Vlamingstraat) the difference between street level and the water is only about 25 cm, while in the Oude Delft (start of this walk) it is about 150 to 200 cm. The water level is exactly the same, namely Delflands Peil = NAP - 0.42 m (Normal Amsterdam Level). The difference is in the street level.
The expansions of the city of Delft over the centuries, took place on peat soil. In recent decades, this part of Delft in particular has subsided due to natural subsidence, groundwater extraction and intensive building. With these processes, the water level and groundwater level have also been lowered. The peat that became 'dry' as a result oxidised and dissolved.

Dutch soil subsides more than expected - research at TUDelft
The map allowed the researchers to distinguish for the first time between the deep causes of subsidence, such as gas extraction, and the effects in the upper few metres. The latter could not be measured directly until now. It turns out that this 'shallow' soil subsidence in several places in the Netherlands is even greater than that caused by the known, deep causes. Especially in the peat and clay areas in the west of the country, this soil subsidence is now clearly measurable, and noticeable last summer, with dozens of houses showing cracks and subsidence due to the drought. Climate change seems to play a major role in this accelerated land subsidence. Relatively warm summers cause peat soils to dry out more, leading to faster land subsidence. This is an irreversible process: the peat oxidises, which also releases more CO2 into the atmosphere. More on this research.

The sliding construction as protection
The construction at the end of the Rietveld to the Schie was installed in 2000 as an emergency measure to protect the Rietveld. There is also a similar construction in Vlamingstraat. In 2008, this construction was modified and is part of the entire system to protect the vulnerable part of Delft.

This structure consists of a fixed vertical sheet pile wall (film water in image 1, 17:31) with a hole in the middle. This hole can be closed by a hydraulically driven vertical slide. The operation is the same as that of the valve weirs.