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Photogrammetric reconstruction of changes in vertical river position using archival aerial photos: case study of the Czarny Dunajec River, Polish Carpathians

Hajdukiewicz Maciej, Wyżga Bartłomiej, Hajdukiewicz Hanna, Mikuś Paweł

Acta Geophysica

2019

Vol. 67, no. 4

1205--1221

Rivers of the Polish Carpathians incised deeply during the twentieth century, but detailed information about the timing and amount of incision of their channels exists only for water-gauge cross sections. Applicability of photogrammetric extraction of digital elevation models (DEMs) from archival aerial photos for reconstructing changes in vertical river position was verifed in the study of a 3-km reach of the Czarny Dunajec River. DEMs extracted from a few sets of archival aerial photos from the years 1964–1994 together with recent orthophotos and DEMs were used in the analysis. Measurements taken in river cross sections spaced at 100-m intervals indicated that on average the lowest point of the channel bed lowered between 1964 and 2009 by 1.74±0.17 m, low-fow water surface by 1.57±0.07 m, active river channel by 1.54±0.12 m and the belt of river migration by 1.03±0.15 m. However, the change in vertical river position during the years 1964–2009 varied greatly along the reach, with the elevation of low-fow water surface lowered by up to 3.61±0.07 m in the upper part of the reach and increased by up to 1.34±0.07 m in its lower part. Combining the information about changes in vertical river position and the width of river migration belt yielded data about the change in sediment volume in the reach, with an average annual loss of sediment amounting to 256±37 m3 per 100-m channel segment. The study indicated that DEMs generated from archival aerial photos can be a useful tool in analysing recent vertical channel changes outside water-gauge stations.