The Importance of Grazing in the Production of Healthy Food

Functional quality of food means dynamic quality, which is the biological value of food use and nutrition. Its importance is in disease prevention, health preservation and market gain

Herbal Medicinal Products in Our Environment

We would think that the ever-appreciated herbs can be harvested almost exclusively in forests and fields. However, many valuable herbs live here in our vicinity, in the cities. Urbanization is arguably the most intense and irreversible ecosystem change on the planet

Modelling the Hydrological Effects of a Levee Failure on the Lower Tisza River

Along the Lower Tisza River (Hungary) the water level of the floods reached new record stages in 1998 and 2006, resulting in 80 cm increase in the peak flood level since the “great flood of 1970”. Due to the gradual weakening of the levee-system caused by the several long-lasting floods, the question has arisen, that as in case of a levee breach or failure how would it modify the hydrological parameters of the river. The aim of the research is to create a hydrological model to analyse the effects (as stage reduction, slope and stream power) of two different levee breaches: one happening before the peak of the flood and another at the time of the flood level. The simulated levee breaching happened on the Tisza River at Mindszent, and the data-set of the 2006 flood was used for the model-ling (at that time no levee failure happened in Hungary, and it was the greatest flood in history). In the simulation the levee was broken at a point, where the channel is very close and intensively eroding, thus there is a real risk of a levee failure. If the levee would be broken a well defined area (reservoir) would be flooded, surrounded by the secondary levees and the rim of the high floodplain. During the simulation the HEC-RAS 4.1. ArcGIS 10.1 and HEC-GeoRAS software were applied. The greatest changes in the hydrology of Tisza occurred in the cross section where the levee breached, though the effects propagated upstream and downstream too. Due to the water outflow from the Tisza the greatest stage reduction effect was 1.54±0.1 m. The slope conditions changed too, as it increased from 4 cm/km to 6.5 cm/km in the upstream reach, while downstream of the failure point it decreased from 3.5 cm/km to 1.9 cm/km. At the same time the stream power increased from 4 W/m to 5.5 W/m in the up-stream section, while it decreased from 3.5 W/m to 1.5 W/m in the downstream reach. Comparing the results of the simulations at different stages (one at the highest stage and one at 1.0 m lower stage) it seems that the hydrological parameters did not change considerably (1%), though in a case of a levee failure at higher the reservoir reached the maximal water level sooner, though less water was stored in it, as the fall of the river was continuous

Recens folyóvízi felszínformáló folyamatok mértékének és irányának vizsgálata a Dél-Alföldön = Research on the rate and intensity of recent fluvial processes on the South Great Plain

Hullámtéri és egyes, a mederben zajló recens folyamatok számszerűsítését tűztük ki célul, 5 kérdéscsoportot fogalmazva meg. Mintaterületül a Maros 50 km-es szakaszát, egy közép- és egy alsó-tiszai hullámtéri részt választottuk. A vizsgálatokhoz a kutatási tervben bemutatott módszereket használtuk fel. Az akkumuláció mértékét a szabályozások óta és egy-egy árvízhez kapcsolódóan vizsgáltuk. A különböző hidrológiai tulajdonságú árvizek által lerakott üledék vastagsága jelentősen eltér még ugyanazon a helyen is, akárcsak a medertől távolodva, vagy a hullámtér magasságának növekedésével. Így a hullámtér víztározó kapacitása is eltérő mértékben csökken, s ez a különbség akár egy nagyságrenddel is eltérhet. Az akkumuláció eltérő tér- és időbeli mintázata előrevetíti, hogy az esetleges szennyeződések is eltérő mértékben juthatnak ki a hullámtérre. A Maros és a Tisza szélessége az átvágások után csökkent, majd a 20. sz. elejére elérte a korábbi értékeket. A 20. század során minkét folyónál jelentős mederszűkülést mértünk, pl. a Tiszán 1929-1957 között 12 %-os szűkülést, a legintenzívebben a partbiztosított kanyaroknál. A Maros leginkább a medertágulatokban szűkült. A szélesség értékek egyre kisebb szórást mutatnak, tehát a medertágulatok felszámolódnak, üledéktároló funkciójuk lassan megszűnik. Ugyanakkor a Maroson a szigetek összterülete jelentősen növekedett. Ennek oka lehet a vegetáció üledékmegkötő hatása, egyes hidrológiai paraméterek megváltozása. | The aim of the study was to measure the rate of some geomorphological processes on floodplains and within the river-bed. Study areas were chosen on the 50 km long section of Maros and on two sites of the Middle and Lower Tisza floodplains. All methods were introduced in the project plan. Aggradation was studied (1) since the 19th c. regulation works and (2) in connection with single flood events. Its rate differs even at the same point, as it is influenced by the hydrology of the flood; but it is influenced by the distance from the channel and the relative height of the floodplain as well. Therefore, the flood conductivity reduction due to aggradation differs along the floodplain. It will also influence the spatial pattern of possible contaminations. The mean width of Tisza and Maros decreased after the regulation works, but this process terminated by the beginning of the 20th century. During the 20th c. intensive tightening was measured along both rivers, i.e. between 1929 and 1957 the Tisza became narrower by 12 %. The most intensive narrowing was detected in case of the Tisza at revetments, and at braids on the Maros. On this river width variability has been reduced, suggesting the decline of braids and their sediment storage function. At the same time the territory of islands has increased, probably due to the invasion of riparian vegetation and the alteration of some hydrological parameters

Characteristics of Point-Bar Development under the Influence of a Dam: Case Study on the Dráva River at Sigetec, Croatia

Before the extensive engineering works the Dráva River had braided pattern. However in the 19-20th centuries river regulation works became widespread, thus meanders were cut off, side-channels were blocked and hydroelectric power plants were completed. These human impacts significantly changed the hydro-morphology of the river. The aim of the present research is to analyse meander development and the formation of a point-bar from the point of view of indirect human impact. Series of maps and ortho-photos representing the period of 1870-2011 were used to quantify the longterm meander development, rate of bank erosion and point-bar aggradation. Besides, at-a-site erosion measurements and grain-size analysis were also carried out. As the result of reservoir constructions during the last 145 years floods almost totally disappeared, as their return period increased to 5-15 years and their duration decreased to 1-2 days. The channel pattern had changed from braided to sinuous and to meandering, thus the rate of bank erosion increased from 3.7 m/y to 32 m/y. On the upstream part of the point-bar the maximum grain size is 49.7-83.4 mm and the mean particle size is 7.6 mm, whilst on the downstream part the maximum grain size was only 39.7-39.9 mm and mean sediment size decreased to 6.1 mm. Due to the coarse sediment supply and the decreasing stream energy the point-bars develop quickly upstream and laterally too

Identification of Riparian Vegetation Types with Machine Learning Based on LiDAR Point-Cloud Made Along the Lower Tisza’s Floodplain

The very dense floodplain vegetation on the artificially confined floodplains results in decreased flood conveyance, thus increase in flood levels and flood hazard. Therefore, proper floodplain management is needed, which must be supported by vegetation assessment studies. The aims of the paper are to introduce the method and the results of riparian vegetation classification of a floodplain area along the Lower Tisza (Hungary) based on automatized acquisition of airborne LiDAR survey. In the study area 15x15 m large training plots (voxels) were selected, and the statistical parameters of their LiDAR point clouds were determined. Applying an automatized parameter selection and 10-fold cross-validation he most suitable decision tree was selected, and following a series of classification steps the training plots were classified. Based on the decision tree all the pixels of the entire study area were analysed and their vegetation types were determined. The classification was validated by field survey. On the studied floodplain area the accuracy of the classification was 83%

Characteristics of point-bar development under the influence of a dam : case study on the Drva river at Sigetec, Croatia

Before the extensive engineering works the Dráva River had braided pattern. However in the 19-20th centuries river regulation works became widespread, thus meanders were cut off, side-channels were blocked and hydroelectric power plants were completed. These human impacts significantly changed the hydro-morphology of the river. The aim of the present research is to analyse meander development and the formation of a point-bar from the point of view of indirect human impact. Series of maps and ortho-photos representing the period of 1870-2011 were used to quantify the longterm meander development, rate of bank erosion and point-bar aggradation. Besides, at-a-site erosion measurements and grain-size analysis were also carried out. As the result of reservoir constructions during the last 145 years floods almost totally disappeared, as their return period increased to 5-15 years and their duration decreased to 1-2 days. The channel pattern had changed from braided to sinuous and to meandering, thus the rate of bank erosion increased from 3.7 m/y to 32 m/y. On the upstream part of the point-bar the maximum grain size is 49.7-83.4 mm and the mean particle size is 7.6 mm, whilst on the downstream part the maximum grain size was only 39.7-39.9 mm and mean sediment size decreased to 6.1 mm. Due to the coarse sediment supply and the decreasing stream energy the point-bars develop quickly upstream and laterally too