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Changes in chemical composition of surface water at the model catchment Lesni potok during the spring snowmelt 2009
Navrátil, Tomáš ; Dobešová, Irena ; Rohovec, Jan ; Buchtová, Jana
Changes of surface water chemistry during the spring snowmelt were evaluated at the forested experimental catchment Lesni Potok found in National Reservation Area Voděradské bučiny. The pH value of surface waters decreased and together with high discharge it launched changes of solutes concentrations. As a good indicator of groundwater in the discharge were evaluated concentrations of Si and isotopic signature of 18O-H2O. The concentration of the main anion SO42- in waters of Lesni potok oscillated during the spring snowmelt in dependence of ratio between melting snow, soil solution, precipitation and groundwater. During the period of increased penetration of surface soil horizons with the water from melting snow causing the increase of DOC concentrations. Concentrations of DOC determined the export of total Fe. Concentrations of Al with DOC did not correlate because the driving factor on concentrations of Al at Lesni Potok is the surface water pH. Concentrations of NO3- were rapidly decreasing during the snowmelt and at the end of this episodic event NO3- concentrations were trivial due to the rapid flushing of soil horizons.
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Experimental study concerning stimulated outflow from porous structures
Pražák, Josef ; Biskup, B. ; Šír, Miloslav
It is generally supposed that the water flow in massive spates occurring in small catchments areas have two components. The first one is the direct surface flow of the water from a preceding rain (new water) the second one is caused by the water “pending” in the soil already before the rain (old water) stimulated by the rain to flow out. The stimulated outflow has been studied in a series of experiments. It was found that in laboratory test, a situation where the stimulated outflow exceeds the stimulating inflow can be simulated in an easy way.
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Multimedia Support in Education of „Geomorphology and Hydrology of the Czech Republic“
Dvořák, Petr
The contribution presents new way of teaching subjects of Geomorphology and Hydrology of the Czech Republic dedicated to university students. This way of teaching is valuable especially because of learning and extending basic geographical Grammar School knowledge. The students get to know specific geographical approaches, methods, techniques and skills. Emphasis is layed on perceiving land divergence, specifics including periodicity and natural relations of geographical phenomenon layout and geomorphological and hydrological process in the Czech Republic.
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Rainfall - runoff relationship in small mountainous catchments
Tesař, Miroslav ; Šír, Miloslav ; Pražák, J.
The singular phenomenon of flow instabilities was observed in a small catchment: in some situations, the water supplied by rain caused a pronounced decrease in the soil water content. This soil water movement can be explained by assuming an irregularly oscillating outflow of soil water into lower horizons. In these situations a large volume of water flows through the soil; on the hydrological scale, this phenomenon forms a great part of the outflow from a watershed. The phenomenon can be described in the frame of the instability driven flow theory and explained as consequence of the porous soil bodyŽs capacity to become conductive in results of a very little change of its moisture. In this way, the soil profile can attenuate or amplify the rainfall pulses during their transformation to the outflow.
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Fishpond management and ecological stability of fishponds -as a key water habitats of the Třeboň region
Pechar, Libor
Fishponds have an important role in the hydrological system of the Třeboň region and generally they represent the most common type of stagnant water habitat in the Czech Republic. Most of the fishponds are several hundred years old, and have therefore lost most of their man-made character. The period of intensification of fish production started in the 1930s, when liming and fertilization of the fishponds became a common practice. Since the 1930s, fish production has increased from a mean of about 50 kg ha-1 to more than 500 kg ha-1. Common carp, Cyprinus carpio L. has been the main cultivated fish species. Management for higher fish stock densities, accompanied by higher nutrient loads result in increasing trophic levels, ultimately reaching a state of 'hypertrophy'. The main symptoms of this state are the massive development of phytoplankton and cyanobacterial ' algal blooms', great fluctuations in oxygen concentrations, pH, which, in turn, destabilise the fish pond ecosystem.
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