2/2012

Abstract

Nowadays, almost every geographic discipline needs to measure geographical data at the field. The same situation is in a fluvial geomorphology. The combination of geomorphology and geoinformatics is a necessity in present time. This article aims to present the latest photogrammetric techniques and procedures that can be applied in fluvial geomorphology. Specifically the use of UAVs (Unmanned Aerial Vehicle) is presented as a source of very accurate geographic data. Based on the orthophoto and 3D terrain models which are generated from the stereo-pairs, it is possible to clearly evaluate the morphological processes that occur in the river channel. One of the conditions is that a very high resolution images are necessary. This article presents specific procedures of preparing of the flight, processes during the flight and subsequent data evaluation. The stereo photogrammetry methods have been known for decades. For using in the UAV photogrammetry, these methods have to be adapted for this specific purpose. The area of interest is a very dynamic part of the Morava River (Czech Republic). In the protected area Litovelske Pomoravi there is a lateral erosion one of a main process in the river channel. This paper also includes a monitoring and evaluation of a meander. The meander has been photographing by the UAV system in two phases: before and after destruction of the meander neck. Photographing with the use of UAVs allows very quick, cheap and accurate morphological evaluation of the fluvial forms. Recommended methods and procedures have to be followed for obtaining the accurate results.

Keywords: UAV, remote sensing, photogrammetry, 3D model

original scientific work

Abstract

The present article deals with the importance of Black alder (Alnus glutinosa (L.) Gaertner) in the riparian stands of torrent Hučava (Protected Landscape Area Poľana) in connection with erosion resistence and stability of the banks of water flows. On aspects of nature and landscape protection and biodiversity the riparian stands are the primary and natur way of reinforcement of the banks of water flows. We found that increase bank stability and bank erosion resistence of water flows in relation the number of Black alder per unit area. Have been investigated and compared 44 experimental banks of torrent Hučava in geomorphological unit Poľana (Central Slovakia). On these experimental banks have been analyzed stability and erosion resistance of the bank of the bed in connection with the various density of stems of Black alder. The factor of stability-Fs on the banks of water flow Hučava was calculated by Bank Stability and Toe Erosion Model (BSTEM). The results indicated close correlation dependence between the density of stems of Black alder and factor of stabilty Fs (correlation coefficient I_yx = 0,914 and determination coefficient I_yx² = 0,835). The calculated results of factor of stability-Fs corresponds with existing erosion damages of the banks which were determined in terrain. The analysis confirmed the influence of alder-stands on bank stability and bank erosion resistance of bed water flows. The results were validated by statistical testing.

Key words: Black alder, riparian stands, bank stability

original scientific work

Abstract

If we consider tree species growing on banks, it is important to notice the effect of underground and aboveground parts. The root system grows through the soil profile and binds soil particles, thus reinforcing riverbed banks. Roots also grow into the zone of continuous flooding where they are a sought-after refuge for water fauna. The aboveground parts of plants relieve the pressure of running water, protect banks against direct effects of waves, drifting of ice and in combination with nonliving reinforcing structures they act as long-term, durable and reliable stabilisation of banks. Protection against water flowing into the stream from adjacent land is very important, too. Banks may also be damaged in rainstorms when runoff is concentrated into one or more main currents, or when water flows back into the riverbed after overflowing onto the flood plain. By stabilising banks by means of grassland in combination with tree species, we can prevent riverbed banks from being damaged by erosion rills that can have a very unfavourable impact on the stability of riverbed slopes.

Key words: Bank stabilization, landscape, vegetation, tree, shrub

original scientific work

Abstract

Water store in unsaturated soil zone was determined by monitoring of water content in soil profile and in localities in region around town Nitra in Slovakia. The localities relate to agricultural cultivated soil, grassland and also to forest ecosystem.

Soil water contents from soil surface to 1,00m were measured by Profile Probe PR2/6 during one year.

The soil surface reacts directly on meteorological conditions primary through evapotranspiration. It is determining the inflow of precipitation into deeper layers of a soil profile. Both physical and hydrophysical properties of the upper soil layer are changed under the extreme meteorological conditions. In case of such conditions the water can flow along preferential pathways down to the groundwater without filling up the soil matrix. Due to extreme consequences of drought and flood in soil and landscape is necessary to know hydrological balance and soil water content. We used historical data about discharge, weather and crops from years 1974 – 1994, as well as measurements of soil moisture in the forest and arable soil, in grassland and Salix viminalis L. According to this information, the baseflow (by ABSCAN), surface runoff (SCS method), water retention and soil water content were calculated and evaluated.

Key words: baseflow, surface runoff, water retention, soil water content

original scientific work

Abstract

Saturated hydraulic conductivity (Ks) was estimated as limit condition of infiltration in model sandy substrate. Infiltration was directly measured with a pressurized infiltrometer and Ks was estimated from mathematical analyses based on Philip´s equation. The substrate was divided in together ten large vessels, nine of them were planted with poplar and one was without vegetation. Results show differences in Ks estimated for the bare and less rooted vessels compare to densely rooted ones. Sandy substrate with higher organic matter shows lower Ks.

Key words:soil organic matter, infiltration, sandy soil

original scientific work

Abstract

If we consider tree species growing on banks, it is important to notice the effect of underground and aboveground parts. The root system grows through the soil profile and binds soil particles, thus reinforcing riverbed banks. Roots also grow into the zone of continuous flooding where they are a sought-after refuge for water fauna. The aboveground parts of plants relieve the pressure of running water, protect banks against direct effects of waves, drifting of ice and in combination with nonliving reinforcing structures they act as long-term, durable and reliable stabilisation of banks. Protection against water flowing into the stream from adjacent land is very important, too. Banks may also be damaged in rainstorms when runoff is concentrated into one or more main currents, or when water flows back into the riverbed after overflowing onto the flood plain.

Keywords: Biotechnical stabilization, bank, reservoir, water, vegetation, geonet

original scientific work

Abstract

The experimental activity within the project Bank Stabilization concentrated on the establishment of ground reinforced stabilization carpets and application of at least three types of geonets and four types (the most frequently used) of grass. The established stabilization carpets were closely monitored for seven months. As a result, we obtained four groups of data. The first group is represented by detailed graphs depicting the speed of the grass root growth through the ground material reinforced by particular types of geonets and their comparison with the speed of the root growth of the same grasses through a stabilization carpet without a geonet. The stabilization carpets were established and monitored in the same growth conditions.

Keywords: Biotechnical stabilization, grass, mixtures bank, reservoir, water, vegetation, geonet,

original scientific work