The Demeroever at the Hoogbrug. Stones in the water.

At the Hoogbrug and the Amerstraat, we see various forms of bank reinforcement.

An example from an earlier period (Middle Ages and Ancien Regime) can be found in the foundations of the ‘Harmonie’. This building was rebuilt after its destruction during World War I. This was done on the foundations of the earlier building. The Demer riverbank has been reinforced here with iron sandstone blocks. These are quite large and came from quarries with high-quality iron sandstone. Iron sandstone and water are not a bad combination in applications such as quays and watermills. When this type of stone fell out of favor for important residences – roughly from the end of the 15th century – it was still used for such applications. We will see this later at the 's Hertogenmills.

Upstream, we see on the right bank that the quay wall was built with bricks. This occurs in the second half of the 19th century, when the Demer, which at that time still has an interesting economic value for the city, is being canalized. During that period, the availability of iron sandstone is already limited. A brick industry is gradually developing, which will experience a remarkable rise in civil and industrial construction. Brick is qualitatively appealing and its size is easily manageable at the construction site. Of course, building a structure with hundreds of thousands of bricks requires a lot of bricklayers and time. However, we see that brick is weathered by the action of water and frost. In a first phase, the joints are affected due to weather conditions or by bacteria, mold, and plant growth. Once the joints are severely weathered, bricks can easily become dislodged from the masonry. In a final, more extreme phase, holes can become so deep and large that the structure of the quay wall is compromised.

A third option we see here for reinforcing the bank was implemented during recent repairs and consists of gabions made of woven wire, filled with rough natural stone blocks. The invention of metal gabions dates back to the end of the 19th century, when the Rebno river in northern Italy broke through its dike, and this was found to be the most efficient and least expensive solution.

In summer, these gabions are completely overgrown, so you can no longer see them.

Jan Rymenams