Search
Search Results
-
Morphometric changes of the River Bodrog from the late 18th century to 2006
28-40Views:40The river regulations of the 19th century have affected each of our rivers to a different degree. In the case of the River Bodrog it was stronger than the average. In our paper a section of the river between Bodroghalász and Szegi was examined, the extent and intensity of river channel changes was intended to be determined. The applied series of maps and aerial photos was georeferred and the river channel was vectorized. The morphometric parameters of the channel were measured and the changes were evaluated using the created database. From methodological aspect we concluded that the 9 variables can be grouped into 3 factors therefore most of the indexes can be substituted. We measured the changes of length and lateral shift of the channel using GIS methods. Three development periods were identified based on our results. In the first period the development of the river was characterized by natural processes. Then, the development of the river altered owing to the antropogenic impacts. In this transient phase the average shifting of the channel was 7.43 m/y. In the third term this value reduces to 0.2 m/y as the river is getting to reach the equilibrium stage.
-
A GIS-based study on the changing course of the River Jiadhal in the Dhemaji district, India
14-27Views:66River bank-erosion, deposition and channel-shifting are considered most dynamic and significant geomorphological processes formed by complex geological, hydrological, and anthropogenic factors. In the present study, river Jiadhal is one of the main sub-tributary of the River Brahmaputra in the Dhemaji district of Assam that changes its channel course frequently due to bank-erosion and sediment-deposition in the intermediate part and lower course of the channel. A study on the changing course of the river Jiadhal was carried out using satellite imageries for the years 1987, 1997, 2007 and 2017. The study found that the changes in the river vary from time to time and the bank-erosion and sediment-deposition fluctuate from place to place. The total area of bank-erosion is 13.34 km2 from 1987 to 2017 and the total area of sediment-deposition is 14.59 km2 from 1987 to 2017. This paper evaluates how the shape, size and position of the Jiadhal River have changed from the years 1987 to 2017 using remote sensing and GIS techniques. The study is also necessary for effective management along the side of the river Jiadhal to control bank erosion and to mitigate the adverse impact of erosion and channel-shifting.
-
Recent river channel change detections in the section of the River Tisza above Tiszaújlak (BИЛОК)
123-130Views:167In 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.
-
Active point bar development and river bank erosion in the incising channel of the lower Tisza river, Hungary
13-28Views:233The 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 the 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.
-
Heavy metal content of flood sediments and plants near the River Tisza
120-131Views:77The River Tisza is Hungary’s especially important river. It is significant not only because of the source of energy and the value insured by water (hydraulical power, shipping route, stock of fish, aquatic environment etc.) but the active floodplain between levees as well. Ploughlands, orchards, pastures, forests and oxbow lakes can be found here. They play a significant role in the life of the people living near the river and depend considerably on the quality of the sediments settled by the river. Several sources of pollution can be found in the catchment area of the River Tisza and some of them significantly contribute to the pollution of the river and its active floodplain. In this paper we study the concentration of zinc, copper, nickel and cobalt in sediments settled in the active floodplain and the ratio of these metals taken up by plants. Furthermore, our aim was to study the vertical distribution of these elements by the examination of soil profiles. The metal content of the studied area does not exceed the critical contamination level, except in the case of nickel, and the ratio of metals taken up by plants does not endanger the living organisms. The vertical distribution of metals in the soil is heterogeneous, depending on the ratio of pollution coming from abroad and the quality of flood.
-
Morphology, sedimentology and origin of an anomalous cut-off along the Pravara river, deccan trap region, India
23-43Views:292River 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 occurrence 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.
-
High water level observations along the upper course of the Olt River (Romania) from a hydrological modelling aspect
10-19Views:209Along its upper course, the Olt River (Romania) flows through several settlements, which are endangered by flooding. The multiannual water flow at Tomești station, the first hydrometric station along the Olt River, is 1.51 m3 /s, but in case of extreme events the river flow reached even 41.8 m3 /s. The aim of this study is to analyze the flood events along the upper course of the Olt River (section between Tomești and Cârța settlements) by using the HEC-RAS and the HEC-GeoRAS hydrological modeling software programs. The river cross section model showed how the main channel narrowed (characteristic to some locations) which can be considered as one of the causes of a possible overflow.
-
Mapping of river waterquality using inverse distance weighted interpolation in Ogun-Osun river basin, Nigeria
48-62Views:784Sustainable management of water resources involves inventory, conservation, efficient utilization, and quality management. Although, activities relating to quantity assessment and management in terms of river discharge and water resources planning are given attention at the basin level, water quality assessment are still being done at specific locations of major concern. The use of Geographical Information System (GIS) based water quality information system and spatial analysis with Inverse Distance Weighted interpolation enabled the mapping of water quality indicators in Ogun and Ona catchment of Ogun-Osun River Basin, Nigeria. Using 27 established gauging stations as sampling locations, water quality indicators were monitored over 12 months covering full hydrological season. Maps of seasonal variations in 10 water quality indicators as impacted by land-use types were produced. This ensured that trends of specific water quality indicator and diffuse pollution characteristics across the basin were better presented with the variations shown along the river courses than the traditional line graphs. The production of water quality maps will improve monitoring, enforcement of standards and regulations towards better pollution management and control. This strategy holds great potential for real time monitoring of water quality in the basin with adequate instrumentation.
-
Protected areas in regions of intensive economical activity: conflict of nature protection and nature use (case study of Dovine river catchment)
43-56Views:69Nature protection and economical activity clash of interests is analysed on the example of Dovinė River catchment, situated in the south western part of Lithuania. It is a unique wetland complex consisting from Žuvintas Lake and the surrounding bogs (Fig. 1). Žuvintas Lake became the first protected area in Lithuania in 1937. However, the lake is situated in one of the most fertile region of Lithuania, where the methods of intensive farming activity is being employed for a long time. Eutrophication processes and overgrowth of this shallow lake has been very active during the several decades and the lake has lost its ecological value. Therefore the main goal of this article is to analyse the anthropogenic influence towards the water bodies and protected natural values situated in the territory of intensive economical activity. Cartographical material of different periods is being used for the evaluation of the hydrographical network transformations in Dovinė River catchment. Hydrochemical parameters of the periods 1953–1954, 1960–1961, 1980–1982; 1993–2003; 2004–2005 of the water bodies in Dovinė River catchment are being analysed. The field works in order to investigate the water quality in Dovinė River and it‘s tributaries were made in spring of 2005. Water samples were analysed in laboratory of the Institute of Geology and Geography according water quality analysis methods approved by Lithuanian Ministry of Environment (Table 2). Water quality was evaluated according maximum residue limits (MRL) in surface waters (Table 3). The results of the study showed that although Žuvintas Lake is being protected for 70 years, the farming activity intensified constantly in its catchment. Canalised river beds and sluice–regulated hydrological regime of the lakes diminished the natural self–cleaning abilities of the water system. The average annual decrease of the lake specular surface was about 1,1 ha in the period of 1961–2003. The average annual increase of vegetation area is about 0,14 ha. Even a strong protection regime did not preserve this territory. Therefore, in order to keep the sustainable development in the protected territories the anthropogenic loading from the neighbouring territories (catchment area, etc) must be evaluated. The objectives of nature protection in protected territory could not be attained if there is no regulation of economical activity in the territories surrounding the protected area.
-
Quantitative Morphometric Analysis of Streams in Extreme Humid Areas: A Case Study of the Um-Mawiong River Basin, Mawsynram, Meghalaya
59-75Views:129Quantitative morphometric analysis of the drainage system is essential to characterising a watershed, as all the hydrologic and geomorphic processes occur within the watershed. Consequently, this plays a crucial role in understanding the geo-hydrological attributes of a drainage basin to the terrain feature and its flow patterns, thus enabling the estimate of the incidence of infiltration and runoff and other related hydrological characteristics of a watershed, which strongly impacts natural resource conservation. The study area selected is the Um-Mawiong River basin in Mawsynram, Meghalaya. The basin shows a dendritic pattern that highlights the homogeneity in the texture of the basin. Results suggest that the stream frequency of the basin is 19.10 km², suggesting a faster surface runoff and less infiltration. In addition, it has an Elongation ratio of 0.75 indicating an elongated basin shape. The current study demonstrates that the implementations of GIS techniques are trustworthy, efficient, and capable of managing extensive databases for managing river basins. The present study tries to analyse the linear, areal and relief aspects of the basin using a GIS environment and manipulated for different calculations. The analysis reveals that the total number of stream segments and length are maximum in first-order streams and decrease as stream order increases. The drainage density exhibits a high degree of positive correlation, i.e., 0.87, with its frequency suggesting an increase in stream population concerning increasing drainage density and vice versa.
-
Long-term analysis of River Tisza water level data with regard to the ecological water demand of floodplain water bodies
16-32Views:281One of the main threats of our time is the increasing water demand not only globally, but also locally. These are often met at the expense of ecological water demand, jeopardizing the structural and operational conditions necessary to maintain good ecological status in aquatic and wetland habitats. This is why it is of great importance to explore possible water retention options. In 2019, based on the long-term data series on the water level of River Tisza, we studied the frequency and extent of flooding in the floodplain between Tiszabercel and Gávavencsellő, where there are valuable wetlands, including a ‘sanctuary’-type backwater. This was necessary because recently the floodplains have undergone negative changes. Their water volume has gradually decreased, their valuable wildlife has become rarer, some of them have completely dried out in the autumn and even one of them has burned out. From the analysis of the examined 48-years data, it could be concluded that flooding was relatively frequent in the sampled area, but the extent of water coverage had no significant effect either in space or time. It was also found that only water levels above 700 cm (based on the water meter of Tiszabercel, 98.36 mBf) could adequately ensure that the water bodies are filled up and flushed out. However, there is little chance of this, because of four reasons: (1) water levels of this height are becoming rare; (2) the duration and height of high water levels are mostly short in time; (3) water levels of several water bodies are artificially decreased; (4) the drainage effect of the River Tisza – which has been significantly incised after the river regulation – prevails in the area. Due to all, in the future, there would be a great need to maintain the water levels in the floodplain wetlands as efficiently as possible after the floods – for which we have made specific proposals for the places and methods to preserve the ecologically necessary amount of water.
-
Discussion on Hundru fall as a knick point, Iharkhand, India
44-52Views:261Subarnarekha River lies in the vicinity to the Ranchi mega lineament zone of Jharkhand State. This river links the Tamar Porapahar shear zone and North Singhbhum shear zone. The Hundru falls is the sudden and abrupt drop of elevation (longitudinal profile) of upstream of river Subarnarekha. The basic aim of this paper is to assess the Hundru falls as a perfect citation of an upstream knick point in Indian context. This paper covers the knick point formation of upstream of the Subarnarekha river. This upper catchment is more diversified in the terms of metamorphic and igneous rocks. This zone has crossed a long path with diversified lithospheric adjustment with epirogenic upliftment.
-
Water chemical analysis of the oxbow lakes near the Upper-Tisza River
36-42Views:93The Tisza river plays an important role in the life of Eastern Hungary. Beside the river there are several oxbow lakes, cut off meanders. In this paper the water quality of these lakes was examined from the section of Tarpa to Rakamaz. 45 oxbow lakes were sampled and the chemical parameters were determined. Sodium was used as a pollutant (sewage water) indicator and 2 lakes were found extremely polluted. The lakes outside the dam were slightly polluted because of the lack of renewal of the water body and the ones in the active floodplain had good quality parameters.
-
Hydromorphological assessment of the lower Hungarian Drava section and its floodplain
109-116Views:389The hydromorphological properties of rivers and their floodplains receive increased attention both in basic research and water management. A comparison of hydromorphological parameters before and after river regulation (involving floodplain drainage) provides important information for river management, particularly floodplain rehabilitation. The paper assesses a selected reach of the Drava River and the corresponding floodplain utilising two international approaches, the REFORM framework and the Italian Morphological Quality Index.
-
Land use changes and their effect on floodplain aggradation along the Middle-Tisza River, Hungary
1-10Views:77Land-use changes and their effect on overbank sediment accumulation were investigated on the floodplain of Middle-Tisza River. Military survey maps (1783, 1860, 1883 and 1890) and aerial photos (1950, 1965, 1980 and 2000) were used to evaluate land-use changes and to calculate the vegetational roughness of the area. To determinate the rate of overbank sedimentation sediment samples were collected from a pit, the grain-size, content of organic matter, heavy metal content (Pb, Cu, Zn, Ni and Cd) and pH were measured. Until 1950 meadows and pastures were typical on the floodplain, gallery-forest was along the river, the oxbow-lake and the artificial levee. Notable landuse changes were detected in the second half of the 20th century, as the aerial photo taken in 1965 shows extensive forestry in the area. These land-use changes affected the average vegetational roughness, as it has been doubled since the disappearance of grasslands. Land-use changes highly affect the aggradation, as the increased roughness decreases the flood velocity on the floodplain, causing accelerated aggradation. Using Pb marker horizons and grain-size changes the studied sediment profile was compared to dated profiles (Braun et al. 2003), thus, the sediment accumulation rate could be determined for the periods of 1858-1965 and 1965-2005. According to our measurements the accumulation rate was doubled since 1965, very likely in connection with the doubled vegetational roughness.
-
Morphometric characteristics of a tropical river basin, central Kerala, India using geospatial techniques
1-14Views:251The Thutapuzha watershed (TW) is one among the major tributaries of Bharathapuzha – the largest west flowing river in Kerala, India. Morphometric analysis was carried out to determine the spatial variations in the drainage characteristics and to understand the prevailing geologic variation, topographic information and structural setup of TW using Survey of India topographic maps and ASTER-DEM. Geoprocessing techniques has been used for the delineation and calculation of the morphometric parameters of the watershed. The TW sprawled over 1107Km2 and the study revealed that the watershed includes a sixth order stream and lower order streams mostly dominate the basin with a drianage density of 1.36 m/Km2 exhibiting highly resistant subsoil, dense vegetation, and low relief of surface nature . The study indicate that rainfall has a significant role in the drainage development whereas the drainage pattern is controlled by structure and relief. The watershed of TW is moderate to well-drained and exhibited a geomorphic maturity in its physiographic development. The shape parameters revealed the elongated nature of TW having less prone to flood, lower erosion and sediment transport capacities and drainage network development in the watershed. This study strongly brings to light that the drainage morphometric parameters have the enormou spotentiality to unveil the hydro-morphologicalcharacteristics of the river basins. Integrating hydro-morphological characteristics with conventional watershed assessment methods would have a beneficial effect on judicious watershed management, which helped to formulate a comprehensive watershed management plan.
-
Morphological alteration of the Dráva as the result of human impact
58-75Views:113The Croatian-Hungarian border section of the Dráva River has been undisturbed for almost a century, and it is characterised by unique fluvial morphology (braided pattern and islands) supporting rich habitats and wildlife. However, during the last decades human impact became more and more intensive. Between 1975 and 1989 three water reservoirs were built on the Croatian section of the river, just 16 km from the beginning of the border-section, altering the hydrology and the sediment characteristics of the river. On a local scale cut-offs, revetments and groynes were built. The aim of the study was to evaluate the effect of these human interventions. As the result of the alteration of the hydrology the channel pattern of the Dráva has been changing from braided to meandering, though on the upstream meandering part the territory and number of islands increased due to the drop of water stages. A cut-off and a groyne influenced only the morphology of a short section. As the result of the cut-off braided pattern became more pronounced, and the groyne caused intensive channel aggradation and gave way to lateral island development.
-
Bedload transport measurements on the Maros river, Hungary
37-41Views:177Sediment transport is a vital component in hydrological and fluvial geomorphological studies, however, the temporal and spatial changes in sediment fluxes, and the efficiency of bedload samplers are rarely analysed, as bedload measurements are quite difficult. The aim of the present study is to measure the bedload transport of the sand-bedded Maros River (Hungary) at low stages using the Helley-Smith bedload sampler. In order to understand the variability in the bedload transport, the water stage and discharge across the channel section were also measured. The variability of the bedload was caused by an active in-channel bar and translational sediment pulses. The created bedload transport rating curve could be applied just below 300 m3/s water discharge thus further measurements are needed to evaluate the bedload transport of higher discharges.
-
Grain surface features and clay mineralogy of the quaternary sediments from Western Deccan Trap Region, India, and their palaeoclimatic significance
22-46Views:55Quartz sand grains obtained from a deeply gullied topography along the banks of two tributaries of River Pravara in Maharashtra (India) have been examined with a scanning electron microscope (SEM). Quartz grains have been selected after a heavy mineral separation and micro-photographs of each grain were taken at various angles and magnifications. The sediments reveal features resulting from mechanical grinding as well as from chemical alteration. Conchoidal fractures, cleavage planes, grooves, v-shaped indentations etc. are the mechanical features documented on the grains whereas solution pits of varying sizes and intensity, precipitation surfaces, oriented v-pits, solution crevasses and etching are the features of chemical origin. Several evidences indicate that the samples have undergone digenetic changes. Few grains show the features of intense chemical breakdown. The overall assemblages of the grain surface features suggest that the samples have been subjected to subaqueous transport for a considerable period of time. The minor chemical features such as solution pits or semi circular arcuate steps found in abundance on these grains are due to the dissolution of the sediments in a low energy fluviatile environment. For clay mineralogy, fractions between <2 and <0.2 mm were separated out from the sediments. The clay fractions were then subjected to examination by X-ray diffraction (XRD) of oriented K/Ca saturated samples using a Philips Diffractometer and Nifiltered Cu Ka radiation with the scanning speed of 1 0 2Ө min -1. The main clay minerals for all the samples are identical and show the presence of hydroxy-interlayered smectites with minor quantities of mica, kaolinite, smectites, quartz and feldspar. The first weathering product of the Deccan Basalt (DB) is the dioctahedral smectite. Since the present semi aridic climatic condition of the study area can not transform a smectite to HIS and either smectite to kaolin, it is quite likely that both the HIS and Sm/K are generated in the tropical humid climate of the Western Ghats and then carried through the exiting river system like Godavari, Adula and Mahalungi. Therefore it is evident that the clay minerals present in these sediments represent another climatic history more humid than the one prevailing at present.
-
Field pedological characterisation of two transects along the inner and outer sides of a sixty years old Tisza dike - a contribution to the problem of primary and secondary alkali grasslands
87-112Views:49Two transects were studied by field pedological investigations and soil bulk electrical conductivity measurements in order to understand the effect of a 60 year old dike along the Tisza River on soil formation and vegetation composition. There were no great differences in the soil properties. The soil is more saline and wetter inside the dike and vegetation reflected this environment. We hypothesize that the increasing build up of the riverbed might contribute to the contrast in soil and groundwater salinity between the area inside and the area outside the dike, similarly as conceptualised by Kuti (1989) for the Danube area, but at a much smaller distance.
-
Land use change detection along the Pravara River basin in Maharashtra, using remote sensing and GIS techniques
71-86Views:98In the past few decades there has been an increasing pressure of population all over the world, especially in India, resulting in the utilization of every available patch of available land from woodlands to badlands. The study area represents a basin which is economically growing fast by converting the fallow lands, badlands and woodlands to agricultural land for the past few decades. IRS (Indian Remote sensing Satellites) 1 C – LISS III and IRS 1 C PAN and IRS P6 – LISS III and IRS 1 D PAN Images were merged to generate imageries with resolution matching to the landscape processes operating in the area. The images of the year 1997, 2000, 2004 and 2007 were analyzed to detect the changes in the landuse and landcover in the past ten years. The analysis reveals that there has been 20% increase in the agricultural area over the past ten years. Built up area also has increased from 1.35% to 6.36% of the area and dense vegetation also has marginally increased. The remarkable increase in the agricultural area occurs owing to the reclaim of the natural ravines and fallow lands. Presently the area looks promising, but it is necessary to understand the sedimentological and geomorphological characteristics of the area before massive invasion on any such landscapes because the benefit may be short lived.
-
Land use changes of the riparian landscape in Hungary between 1990 and 2018
82-95Views:127The protection and the restoration of rivers is one of the most important challenges of our time, due to the impact of human activities. The aim of the research was to assess the land use changes in the Hungarian riparian landscape. Several landscape corridors of different (50-100-300-500 m) widths near rivers were analyzed since 1990, using the CORINE Land Cover database. Positive changes in the land use of riparian landscape can be seen: continuous increase in the case of forest areas; and slight decrease in the extent of agricultural land since 1990. Unfortunately, the extent of grasslands and other near-natural areas is reduced; and there has been a steady increase in built-up areas. Examining the changes in built-up areas in more detail, a big increase is shown by the extent of urban green areas. As a continuation of the research, an evaluation methodology is being developed to determine the restoration potential of urban rivers on study area level and on national level. The results presented in this paper on land use changes and land use conditions can be useful for the research about restoration potential at national level.
-
Spatial pattern of soil erosion using RUSLE model and GIS software at the Saf Saf watershed, Algeria
31-47Views:158Soil erosion is one of the problems threatening the Algerian environment. In agriculture, soil erosion leads to the thinning of the topsoil under the effect of the natural erosive forces of water, or under the effect of agricultural activities. The present study aims to estimate average soil loss rate and to identify vulnerable zones. Through the integration of RUSLE model at the Saf Saf watershed, various parameters are utilized such as the rainfall erosivity factor (R), soil erodibility factor (K), slope length - slope factor (LS), crop management factor (C) and practice management factor (P). All these parameters are prepared and processed through a geographic information system (GIS) and remote sensing using various database sources. The results reveal that the river basin has an average annual soil loss of 3.9 t ha−1 yr−1, and annual soil loss of 4.53 million tonnes for the period 1975-2017. Meanwhile, eighty five percent of the study area is experiencing acceptable rate of soil erosion loss, which is ranging between 0 to 5 t ha−1 yr−1. The present study of risk assessment can contribute to understand the spatial pattern of soil erosion in order to use appropriate conservation practices for sustainable soil management.
-
Evaluation of environmental condition: water and sediment examination of oxbow lakes
84-92Views:57As a result of the river regulation a number of oxbow lakes have arisen in the floodplain of the Lower-Tisza. The floodplain lakes represent natural values and major recreation areas of the lowland region. Due to the human activity the oxbow lakes' condition declined. It can be shown by the water quality, the channel discharge by deposit, the high eutrophication of the lakes and the heavy metal elevation of the sediment. Discovering these processes, analysing the condition and recultivation of the oxbow lakes came into prominence only in the past few years. Our research aims to conclude the current environmental pollution of the oxbow lakes from statistical analyses of the heavy metal content of the sediment and from the water quality data. The oxbow lakes have been classified by chemistry instead of chemical. Results of the research show differences between the floodplain oxbows and the lakes outside the dam in terms of the quality of the sediment and the nutrient content of the water.
-
Accumulation studies at specific sampling areas of the active floodplain in the Upper-Tisza region
14-22Views:216In this paper the rate of accumulation was studied along four VO floodplain cross sections of the UpperTisza region between 1974 and 2014. VO floodplain cross sections are based on a mapping base-point grid (established in 1890), and they are located a few kilometers from each other. Furthermore, the roughness changes of different surface types, crossed by the VO floodplain cross-sections, were also determined between 1965 and 2015. The accumulation studies were extended to include the accumulation rates of the cut off meanders located along and/or close to the VO cross-sections. The roughness values increased in all four floodplain VO cross-sections since 1965; in two of them it reached or approximated 100 %. The average accumulation along the VO cross-sections was between 28 and 47 cm (0.73–1.23 cm/year) during the 38-year period. However, its areal distribution showed large differences. The highest values (169–309 cm, i.e. 4.44–8.13 cm/year) were found at the lowest points of the cut off meanders and swales in every case. The accumulation rate of the examined three cut off meanders near the floodplain cross-sections (140 and 1570 meters from the river bed) was lower (0.84–2.5 cm/year), but the study period was significantly longer (154 and 161 years, respectively). Comparing the values of the two periods, it is obvious that the accumulation of the active floodplain accelerates, presumably due to the significant increase of surface roughness.