Search
Search Results
-
Morphometric changes of the River Bodrog from the late 18th century to 2006
28-40Views:32The 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.
-
Protected areas in regions of intensive economical activity: conflict of nature protection and nature use (case study of Dovine river catchment)
43-56Views:63Nature 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.
-
Long-term analysis of River Tisza water level data with regard to the ecological water demand of floodplain water bodies
16-32Views:252One 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.
-
Hydromorphological assessment of the lower Hungarian Drava section and its floodplain
109-116Views:334The 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.
-
Evaluation of environmental condition: water and sediment examination of oxbow lakes
84-92Views:35As 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.
-
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:44Two 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.