I want to create a background map of a DEM (1m spatial resolution) to show the study area. The study area (Northern Germany) contains many water bodies. I have problems with the visualisation of these water bodies (using QGIS) as

  1. the lakes surfaces do have different pixel values, so it's not possible to just set a minimum threshold to visualize the water bodies because then areas of the non-water terrain fall under this category (info: each lake has one pixel value) --> see picture below


  1. the lake-shapefiles that I have (e.g. OSM or ATKIS DLM) are not precise enough (measuring instruments are positioned right at the shores or in a certain distance from the shores within and outside the water bodies --> DEM shows the most precise boundaries).

I am thinking about extracting a mask with the water bodies from the DEM, but I am not sure about the method. In my understanding, I could buffer (approx 2m) the lake-shapefiles that I have (they do mainly display the existing water bodies a little bit too small), and then extract areas with a min amount of pixels with the same value (= water surface) - but I don't know how that could possibly work...

Does anybody have a tip how to extract the water bodies or how to color areas with a certain amount of pixels with the same value next to each other (= the water bodies)?

enter image description here

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