Virág Árpád: A Sió és a Balaton közös története. 1055–2005 (KÖZDOK Kft., Budapest, 2005)

The common history of Lake Balaton and the Sió Canal (1055–2005)

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THE COMMON HISTORY OF LAKE BALATON AND THE SIÓ CANAL (1055-2005)

Mediterranean in character. During this period referred to by the climatologists as „ the Roman optimal climate” the water level in Lake Balaton has presumably surpassed El. 104.7 m (reading +62 cm on the present Siófok gauge, the „0” of which is at El. 104.08 m above the Adriatic datum) and spilled into the Sió Valley on rare occasions alone. The Roman graves found in the presently inundated lake bed close to the shoreline are also regarded evidences of low lake levels during the Roman era. Prompted by the account of Sextus Aurelius Victor in his „História Romanae ...” according to which Emperor Galerius had deforested tracts of land in Pannónia and drained Lake “Pelso” to the Danube through a sluice built at Siófok in 293 B.C. it was widely believed in the 20th century that Lake Balaton was drained by the Romans. Masonry mins excavated close to Siófok during the relocation of the railway line were associated by some scientists with the Roman sluice. Concluding the ensuing debate it was agreed that the Romans have never released water from Lake Balaton, but have probably drained the marshes in the Sió Valley during wet spells.

The water balance of Lake Balaton has normally been a positive one. Present Balaton Minor existed during the Roman era (one of the Roman Emperors was bom at Fenékpuszta), the wetlands between Boglár, Fonyód and Máriafürdő, further the one called Berek extended deep South along the Border ditch.

The Roman rule in Pannónia was replaced by that of the Huns for two decades, who were followed in rapid succession by the Ostrogoths, the Lombards, and then other minor tribes, which had passed without leaving any significant archaeological trace. Neither during the cool and dry climate which had prevailed in Asia and Europe from the end of ht e 4th to the end of the 8th centuries rose the lake level high enough to overtop the littoral sand dunes and to spill often into the Sió Valley. At the time of the Hungarian conquest (late 9th century) and during the 10th century the lake level was as low as in the earlier ones and runoff conditions underwent no changes in the Sió Valley.

After the establishment of the Hungarian state in the 11th century the hydrographical changes of Lake Balaton and the Sió Valley can be traced more reliably with the help of letters of deed, donation, foundation and other documents, the first maps appearing in the 16th century only. In the letter of deed by which King Andreas I has founded the Benedictine Abbey of Tihany, a ford is also listed among the properties donated, as "... on the stream called Fok emerging from the lake there is a section where it can be crossed over a bridge, but often also by wading. ” The boundaries of the abbatial properties were confirmed over a century later by King Andreas II, stating that “on the SE shore of the lake commonly called Balaton the boundary shall start, where the stream Fok emerges therefrom; beyond this point the whole area shall be church property. The boundary stream continues southward down to Losta village, where it forms an island, which shall also belong to the abbey together with the mill sites. ”

A document falsified towards the end of the 14th century, but backdated to 1092 reads as follows: ‘‘Losta village, with the mills at Fok and the toll-house of Fok village are in Somogy County. ” From the property descriptions it was confirmed over a century ago in the history of the abbey that: ‘‘Losta village was built on the banks of the Fok Stream close to the mouth, where an island developed. Losta island had to be close to the mouth, because Cletus village, (the present Kiliti) is over four kilometres from the mouth of the Fok stream. Midway between the two was probably Losta Island and on the northern tip thereof, or close thereto was Losta village. ”

The documents from the 11th—14th and the descriptions, together with the manuscript maps from the 17th—18th centuries, agree on the position of the lake-outlet Fok stream and Losta Island. The outlet appears to have varied, or even dried up completely during the 11th to 14th centuries, depending on the actual lake level. The water passing down the Sió Valley is mentioned in the documents as the Sárvíz (Mud flow) from the 14th to the end of the 17th century, implying that the valley floor was covered with marshes along the entire length. The Sárvíz name was changed to Sió stream early in the 18th century and covered the full length from Simontornya down to the Danube.