Search

Search Results

• Land use changes and their effect on floodplain aggradation along the Middle-Tisza River, Hungary

  1-10

  Tímea Kiss

  Andrea Sándor

  Views:

  67

  Land-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.

• Soil aggregate stablity, organic carbon and plant available nutrient contents (N,P) in soils of prehistoric mounds after abandonment of cultivation

  42-50

  Ágnes Botos

  Vivien Ökrös

  Csaba Tóth

  Views:

  137

  Prehistoric mounds are valuable archeological and nature conservational sites of the Hungarian lowland. However, due to the machinery cultivation most of them were plowed during the 20th century. After setting new legislative frames of their preservation, former cultivated mounds were abandoned and spontaneous regeneration processes of vegetation and soil could initiate on the ex lege mounds. Four mounds situated within the National Park of Hortobágy were investigated after their cultivation were abandoned, regarding their most important soil properties such as aggregate stability, bulk density, nitrogenous and phosphorous content, pH, organic carbon content and secondary carbonates.