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Active point bar development and river bank erosion in the incising channel of the lower Tisza river, Hungary
Published December 20, 2019
13-28

The development of point-bars and bank erosion are critical near-bank processes, as they indicate
the sediment and hydraulic regime of a river system, thus, they refer to the equilibrium conditions of
a channel. However, throughout history, rivers have been modified for various benefits which change
the development of point-bars and th...e rate of bank erosion. In the Lower Tisza River (Hungary), river
regulations influenced the channel and floodplain development, altering the natural fluvial processes.
The aim of the research was to determine the rate of near-bank processes and to make trajectory for
future river evolution to support future engineering works. The bank erosion and point-bar development
at human-influenced and freely meandering sections of the Tisza River were monitored since 2011.
Behind a collapsed revetment, the bank erosion rate was 0.6 m/y, while at a freely meandering section it
was 2.3 m/y. The studied point-bars are located in revetted and freely meandering sections. Their surface
eroded within the period. These intensive erosional processes refer to an incising meandering channel,
which must be considered during future planning of in-channel structures (e.g. revetments, bridges),
thus, geomorphic methods must be considered in any river engineering scheme.

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Morphological grouping of fossil floodplain forms in the northeastern part of the Pannonian plain
Published August 2, 2020
21-33

The Bereg Plain is located in the northeastern part of the Pannonian Plain, close to the Carpathian
Mountains. Clarification of the evolution of its topography is essential for the development of the whole
area. The former single alluvial cone has been fragmented, some parts of it subsiding and others rising.
The displacements of the s...ubsided parts of the area were dominated by erosion processes, as in the Bereg
Plain. As a consequence, a significant part of the sand in the area has been degraded and only traces of it
remain in the Bereg Plain. The existing sand patches have been identified and classified using DEM. In the
area identified 10 floodplain islands not yet mentioned in the scientific literature. The investigation of
the numerous islands – hitherto unknown and be-longing to different morphological types – enabled us a
reconstruction of the surface development of the Bereg Plain that is more differentiated and precise than
ever before. Based on their morphogenetic properties, these floodplain islands can be divided into three
main types: (1) erosion islands, (2) point-bars, (3) coastal dunes. In the area, I could recognize no pattern
or re-gularity in the position of the individual forms of any type. In many cases, the direction of the
longitudinal trends is perpendicular to one another, which excludes their Aeolian origin. The sediment
of the floodplain islands mainly consists of medium-, small- and fine-sized sand, but the settlement of
loess-mantled and loess-like layers among the sandy sediment of certain forms can also be observed. The
layer with 15 % lime content and 53–60 % loess fraction (0.05–0.01 mm) – found in the 110–50 cm high
section of the erosion island called the Homok-tanya in Mátyus – can be considered a typical loess, based
on the detailed parameters. Its formation in all probability took place at the same time and under similar
conditions than that of the more than 2 m thick aeolian loess mantle found in the Nyírség area, some 10
km west from there, which had accumulated before the Bölling period. In case of an erosion island 2.5
km to the south and lying some 2 m lower, such a loess mantle cannot be found anymore, despite the fact
that the sandy layers of the two sediment series are almost completely identical. The background of this
phenomenon is the more active and frequent, mainly erosional fluvial processes – because of the lower
position –, which eroded the loess mantle.
The composition of the surface sediments is de-termined by the absolute altitude as well. The cover
sediment of the lower-lying islands is identical to the finishing silt-clay deposits found at the alluvial
parts of the Bereg Plain, whereas the surface of higher-lying forms that have not seen flood for ages, is
covered by sand or loessy sand.

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15
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UAS photogrammetry and object-based image analysis (GEOBIA): erosion monitoring at the Kazár badland, Hungary
Published September 12, 2016
169-178

A remarkable badland valley is situated near Kazár, NE-Hungary, where rhyolite tuff outcrops as greyish
white cliffs and white barren patches. The landform is shaped by gully and rill erosion processes. We
performed a preliminary state UAS survey and created a digital surface model and ortophotograph. The
flight was operated with manu...al control in order to perform a more optimal coverage of the aerial images.
The overhanging forests induced overexposed photographs due to the higher contrast with the bare
tuff surface. The multiresolution segmentation method allowed us to classify the ortophotograph and
separate the tuff surface and the vegetation. The applied methods and final datasets in combination with
the subsequent surveys will be used for detecting the recent erosional processes of the Kazár badland

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139
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Studying the development of fluvial landforms in the Berettyó-Körös Region using geoinformatic methods
Published September 4, 2016
137-144

Development of fluvial landforms from 1980 till nowadays was studied based on digital elevation maps
(DEM) composed from contour lines of topographic maps, field data obtained by RTK GPS and aerial
photos taken by a drone. Greatest denudation of 6-9 metres was measured in the eastern side of the
erosional valley at Pocsaj caused by pip...ing and mass movements. As a result, the valley widened and
slightly deepened. Since 1980 around 1-2 metres of accumulation and erosion of similar rate have been
measured in the secured floodplain environment dissected by abandoned beds, point-bars and swales
at Kismarja. These values, however, rather reflect the geometric uncertainties and deficiencies of the
contours of topographic maps than real land changes. Therefore topographic maps can give reliable basis
for studying the development of lowland landforms only if they depict adequately large sized (minimum
100 x 100 m) positive or negative forms with great height difference as well (minimum 8-10 m). Accuracy
of DEMs composed from aerial photos using photogrammetric methods – taking off height faults caused
by vegetation – is around the same as that of the models created on the basis of RTK GPS measurements.

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131
3
Morphology, sedimentology and origin of an anomalous cut-off along the Pravara river, deccan trap region, India
Published October 7, 2021
23-43

River meanders have always been an intriguing subject in fluvial geomorphology because of their ubiquity, dynamism, remarkable forms and practical consequences of their movement. Sometimes a relatively straight channel flowing over bedrock may develop a lone meander bend cut-off which is very out of the place from the surrounding area. The occu...rrence of a sudden bend along a river may not be a meandering bend but may be manifestation of sudden change in the river dynamism due to many reasons, such as, lithology, change in rainfall regime, tectonics etc. The formation of such features highlights the behavior of river in the past. One such striking feature has been observed along the River Pravara in the Deccan Trap Region, Maharashtra, India. Rivers in Deccan Trap Region do not meander and form cut-offs by rule. It is rocky country where rivers flow in deeply incised bedrock. Hence, the observed feature displays a striking anomaly in this region. Hence, an attempt has been made in the present paper to evaluate the mode of formation of this single cut-off along this channel. Morphological and sedimentological data were generated and analyzed for the channel loop and the link channel to understand the competence of the river in the past and present which were directly or indirectly responsible for the development of this channel anomaly in this reach. Based on the results of the analysis and intensive field observations, it has been inferred that this is a classic example of natural morphological adjustment of a river when a set of events occurred, first retardation of vertical erosion encountering bedrock followed by series of floods to induce the channel to divert from the original path to resume the present course. Presence of a tributary further aided to the process of the loop development. The study can provide additional knowledge to the studies involving anomalous channel cut-offs at any part of the world.

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212
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Recent river channel change detections in the section of the River Tisza above Tiszaújlak (BИЛОК)
Published August 31, 2016
123-130

In the section above Tiszaújlak, despite the presence of embankments, the River Tisza shows active meandering tendency and it splits into branches resulting in side channels, dead channels and backwaters that follow the main channel. In our work we examined the right- and the left-side riverbank sections of the River Tisza, between Tiszaújlak... (Вилок) and Tiszasásvár (Тросник), as well as between Tiszaújlak and Tiszapéterfalva (Пийтерфолво), to reveal the extent of bar depositions between 2006 and 2015, and to what extent the intensity and direction of the riverbank formation processes were influenced by the material of the bank and the plant coverage, its rate and characteristics. We tried to reveal which sections were eroded by the river and what security risks they have for the safety of the settlements along the Tisza River. On the right side of the Tisza River riverbank 51, and on the left side 62 main measuring points were recorded by GPS positioning satellite in 2009, 2010 and 2015. Our results were compared to the satellite images of Google Earth taken in 2006, too. According to our experience, in several bends of the examined sections of the river, active bar deposition can be observed; in some cases more than 100 m of bar depositions were detected.

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118
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Vegetation changes of Sundarbans based on Landsat imagery analysis between 1975 and 2006
Published June 23, 2014
1-9

The Sundarbans in Bangladesh and India is the largest single block of tidal halophytic mangrove forest in the world. This forest is threatened by effect of climate change and manmade activities. The aim of this paper is to show changes in vegetation cover of Sundarbans since 1975 using Landsat imagery. Normalized Difference Vegetation Index is ...applied to quantify and qualify density of vegetation on a patch of land. Estimated land area (excluded water body) of this forest is 66% in Bangladesh, and 34% in India, respectively. Net erosion since 1975 to 2006 is ~5.9%. In vicinity of human settlement, areal changes are not observed since 1975. The mangrove forest is decreased by 19.3% due severe tropical cyclone in 1977 and 1988. Moreover, the dense forest is damaged by about 50%. However, more than 25 years is taken by Sundarbans to recover from damage by a severe tropical cyclone. The biodiversity of Sundarbans depends to fresh water flow through it. Therefore, the future of Sundarbans depends to the impact of climate change which has further effect to increasing intensity and frequency of severe tropical cyclone and salinity in water channels in Sundarbans.

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