10 June 2024

Island in the Sea of Nettles



In summer, the defence mechanisms of the Danube islands are activated. The wildlife puts the most beautiful floodplain landscapes under strict protection, drawing a smokescreen of insects, spiders and bloodsuckers, installing mine barriers of impenetrable soot and blackberry bark, forming barbed wire barriers of man-high nettles, and if all this were not enough, the flooding due to heavy rainfall overwhelms the remaining paths in the riverine forests. Even the best armour, long-sleeved shirts, thick trousers, hats, mosquito repellent and rubber boots won't help, there are simply some islands where access through ditches and bushes is impossible. One such place is the former sand bar at the foot of the loess wall in Dunaföldvár, which has been given its own name, Felső-Öreghegyi Island. 

In Dunaföldvár, the Felső-Öreghegy is a loess hill, which is thoroughly dug into by the Danube from the east. The middle section of the ridge is missing from the NNE-SSE line of hills, which is the  characteristic tectonic direction of the Transdanubian Mezőség plains, and therefore it breaks off with a steep slope towards the Danube, which is also characteristic of the eastern border of the Mezőség. The inner curve of this bend formed a sand bar, which soon became an island as a result of the subsidence of the average river level due to river regulation, the construction of a cross barrier prevented further erosion of the bank, but this ultimately meant that the island is now unrecognisable from the bank, from the main branch and even from the József Beszédes bridge. The same can be said of the huge Felső Island of Dunaföldvár on the left bank, which is adjacent to the half-broken ice-cream-shaped Felső-Öreghegyi Island at river kilometer 1562. 

This strange shape is due to the fact that the island's part south of the cross dam is a stone dyke, while the upper part widens considerably at the expense of the tributary. The name tributary is an exaggeration, as the former riverbed is divided into two sub-basins, or oxbow lakes, of which the northern one is the larger, longer and has the larger open water surface. On the morning of 2 June 2024, at a water level of 107 centimetres at Dunaföldvár gauge at the time of rising water level, there was no connection between the two sub-basins, but it was not long before the water broke through the unrecognisable cross-barrier, which was particularly difficult to find because of the circumstances described in the first paragraph. Its position could be determined by the crop stones that had emerged in a wild boar's pit at the foot of the riverbank, which in many places is steep as a castle wall, but the soil had almost completely buried it. Traces of rainfall destroying the loess wall could be observed in several places, with the material deposited almost immediately entering the tributary, constantly filling it.

The unseen Felső-Öreghegyi Island seen from the top of the Dunaföldvár loess wall.

The southern tip of the island, at rising water level.

The oxbow lake surrounded by the sea of nettles.

View of the cross dam, buried and overgrown beyond recognition.

The steadily rising water level is submerging the riparian vegetation.

Remnants of the cross dam near the loess wall.

The open water surface of the upper lake.

Still life with nettles.

View from the cross dam towards north.

At this water level, the cross dam is the only possible way to enter the island, but the man-high nettle forms an impenetrable barrier on the island's steep slopes, effectively preventing more detailed documentation of the island. The presence of the large nettle is an indicator of the abundant nitrogen content of the soil, both on the island and in the riverine forest, and has even obliterated the path leading to the island. It is therefore definitely worth returning here at lower water levels, well away from the growing season. 

Translated with DeepL.com (free version)

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