Search
Search Results
-
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.
-
Types and characteristics of the oxbow-lakes in Lower-Tisza-valley - classification from landscape planning perspective
19-25Views:67The study area is located in Hungary on the South of the Great Plane called Alföld in Hungarian. There are ten oxbow lakes are located in the region of the Lower Tisza Valley. The quality of the area’s oxbow lakes are rather different. There are protected, highly valuable sites in terms of landscape and nature conservation, yet degraded areas utilized for economic purposes can also be found. In the course of river-control in the Lower Tisza Valley was affected by the 84-90th cutoffs, therefore oxbows have been formed in the area. Four of these oxbows are on the part that is not effected by floods, and six of them are located in the active floodplain.The attributes or usage of oxbow lakes allow for a complex system of categorisation. The assessment and classification of oxbow lakes can establish the grounds for assessment, as well as for planning the interventions of landscape restoration.
-
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.
-
Mapping aquatic vegetation of the Rakamaz-Tiszanagyfalui Nagy-Morotva using hyperspectral imagery
1-10Views:190Rapid development in remote sensing technologies provides more and more reliable methods for environmental assessment. For most wetlands, it is difficult to walk-in without disturbing the endangered species living there; therefore, application of opportunities provided by remote sensing has a great importance in population-mapping. One effective tool of vegetation pattern estimation is hyperspectral remote sensing, which can be used for association and species level mapping as well, due to high ground resolution. The Rakamaz-Tiszanagyfalui Nagy-morotva is an oxbow lake, located in the north-eastern part of Hungary. For this study, a wetland area of 1.17 km2 containing the original water bad and shoreline was selected. For the image analysis, images taken by an AISA DUAL system hyperspectral sensor were used. At the same time, 7 main vegetation classes were separated, which are typical for the sample plot designated on the test site. Classification was performed by the master areas signed by the most common associations of the Rakamaz-Tiszanagyfalui Nagy-morotva with determined spectrums. During the image analysis, SAM classification method was used, where radian values were optimized by the results of classification performed at the control area.
-
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.
-
The Mass Ratio of the Epiphytic Periphyton of the Nyéki-Holt-Duna
232-241Views:203The knowledge of the periphytic structure is important for the fact that the composition of epiphytic periphyton indicates the ecologically different habitats, the biological state of water-quality and its changes. Plants like reed, great bulrush, saligot, pondweed, and water-rose separately were collected from the different sampling sites for the epiphytic periphyton examination. We performed the comparability of the monitoring systems based on the periphyton category (mass), the group (ash%), the type (chl-a%), and the character (AI), and we used the biological indicators to determine the ecological state. Taking into consideration the examined years and the results of the analysis of the mass and the chemical composition of the periphyton, by means of the NTPI, the overweight of the good ecological state is characteristic of the Nyéki-Holt-Danube.
-
Present tendencies in landscape planning and recognition of the opinion of local citizens on the example of the Tiszazug
1-9Views:168A survey based on online and face-to face interviews with 104 persons who live in the Tiszazug in the central part of the Great Hungarian Plain. According to the answers the character of the landscape here would change dramatically by disappearance of oxbow lakes, floodplain forests and vineries. The decreasing population and aging of the citizens result in decreasing intensity of landuse, increasing number of abandoned buildings and the attractiveness of the landscape is spoiled by illegal waste disposals and weedy water banks.
-
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.