Rozwój przedsudeckiego odcinka doliny Nysy Kłodzkiej w świetle fotointerpretacji zdjęcia lotniczego

Abstract

DEVELOPMENT OF THE FORE-SUDETIC PART OF THE NYSA KŁODZKA RIVER VALLEY IN THE LIGHT OF AIRBORNE SURVEY PHOTOINTERPRETATION

Summary

Geological investigations of the Fore-Sudetic part of the Nysa Kłodzka river valley have been completed with the interpretation of airborne survey. On this basis a detailed geomorphological map has been worked out (Fig. 1), which proved useful in the presentation of geological picture more in detail (Fig. 2). The interpretative research has been compared with the observations of gravel pits and outcrops found to occur within the river valley.
Stereoscope observations of the photograph allowed the author to distinguish not only the detailed extent of mesoforms, like terraces, but also numerous mcroforms in their outlines. For the most part these are erosional edges, abandoned river bends and swells of aggradational deposits that build accumulation banks.
In this case different undercut forms of meanders and accumulation banks adapted to their shapes are the main forms.
Airborne photograph allows, on the basis of the detailed measurements of river meanders, the principal parameters of a river to be calculated; these are: Q – mean long-term flow, J – decrease of water table, B - width of river. As an example the mean flow of the Nysa Kłodzka river has been calculated for the sector from Pomianów Górny to Jezioro Otmuchowskie (lake), 17,65 m³/s, and from Otmuchów to the town Nysa, 24,14 m³/s, within the youngest terrace, and for the first sector of the higher terrace, 15,44 m³/s.

Moreover, due to this method the tangential influence of the river upon its banks has been explained, too. Within the sector from Pomianów Górny to Jezioro Otmuchowskie (lake) the development directions of the meanders (Fig. 3) demonstrate that for the most part the river has eroded its northern margin, nevertheless it flows directly under the high erosional southern edge, tending to move it southwards. In addition to this, within this area 96% of tributaries and of dragged materials flow into the Nysa river, even so the river stands in opposition to this process, too. It appears that here phenomena of endogenous forces occur, resulting in the uplifting of the northern areas; this of course causes a displacement of the Nysa river bed southwards.