What happened to the trenches after WW1?

After world war one ended what happened to the trenches that were dug... were they left or filled in?

help plz...

Except for a few that have become part of battlefield museums, as described in

http://www.warmuseums.nl/gal/144gal.htm ,
they have all been filled in.

After World War 1, the fate of the trenches varied depending on the region and the specific circumstances. In some areas, the trenches were left as they were, while in other places, they were filled in or modified for various purposes.

Many of the trenches in the Western Front were abandoned and gradually filled in by nature over time. The enormous scale of the trench systems made it impractical to completely remove them. As a result, the ground was often left uneven and scarred, with traces of the trench system still visible today.

In some cases, the trenches were repurposed or modified for civilian use. For example, farmers in affected areas may have filled in parts of trenches to use the land for agriculture. Some trenches were turned into ditches or drainage channels. Additionally, some areas converted portions of the trenches into memorial sites or tourist attractions. Notable examples include the preserved trench systems in Ypres, Belgium, and the Somme, France.

However, it is important to note that the fate of the trenches varied across different regions, and local conditions and decisions played a significant role in determining what happened to them after the war.