Between 17.6.2022 and 25.8.2022, a new erosion ditch, about 6m deep, formed in the centre of the former glacial lake.
The panoramic photo below shows a 360° view from location 15. The beginning of the newly created erosion ditch can be seen in the panoramic photo above the yellow dot.
Former glacial lake with new erosion ditch. Status 25.8.2022
Source orthophoto: Federal Office of Topography swisstopo. The orthophoto shows the situation in summer/autumn 2021.
The distance between points 15 and 22 is 46m (Measured on map.admin.ch).
Legend
- Red dot 15 = Our
Location 15.
- Red dot 21 = Our
Location 21.
- Red dot 22 = Our
Location 22.
- Yellow lines = Viewing angle of the repeat photos of the corresponding locations.
- Lines in magenta = Beginning/end of view
- Orange dots = Approximate course of the new erosion trench.
- Blue dots = Course of the glacial stream.
- Green dots = Course of a part of the glacial stream at high water.
Since the lake was phased out in September 2019, we never entered the former bottom of the lake.
This for two reasons:
- The ground around the lake and also in the western part of the Gamchigletscher is normally well accessible. As soon as water penetrates the ground (e.g. Schmezl water at the edge of the glacier), the ground quickly becomes marshy to very marshy.
- The bottom of the former lake never looked trusting to us. For this reason, we never entered this area.
The formation of the erosion ditch could have proceeded as follows:
- The bottom of the lake forms a trough. Rainwater collected in the trough and seeped away, softening the ground.
- According to the statements of locals, a strong storm raged in the region of the Gamchi glacier around 10 August 2022. During this storm, the level of the glacier stream (= blue dots in the orthophoto) rose so much that it overflowed its banks and some of the water flowed into the hollow of the former lake (= green dots in the orthophoto). Corresponding signs can be seen in the comparison photos of location 15 (Comparison of the photos from 16.7.2022 and 25.8.2022).
- The depression of the former lake was not able to hold the water. The water sought a path towards the existing erosion ditch. The softened soil was carried away and the erosion ditch was formed.
It is possible that the sudden leakage of a so-called bag could have led to a similar effect.
It is also conceivable that the erosion ditch was formed gradually. But this happened within just over two months.
Newly created erosion ditch from location 15. Status 25.8.2022
View into the newly created erosion ditch. Status 25.8.2022
Little clear water flows at the bottom of the erosion ditch.
View into the middle part of the newly created erosion ditch. Status 25.8.2022
View from location 22 into the erosion ditch. Status 25.8.2022
In the photo from the right, the newly created erosion ditch flows into an erosion ditch that already existed before 17.6.2022. Between 17.6.2022 and 25.8.2022, the existing erosion ditch became larger.