National Repository of Grey Literature 62 records found  previous11 - 20nextend  jump to record: Search took 0.01 seconds. 
Runoff from a small mountain basin due to soil water oversaturation
Vondrka, A. ; Šír, Miloslav ; Tesař, Miroslav
Analysis of runoff in a small mountain basin enables better understanding of the mechanisms of extreme runoff formation in small watersheds. Especially the proportion of old (soil) and new (rain) water in various stages of runoff is evaluated. The paper describes a method to determine when the new rainwater flows in a stream. The method is based on measurements of water conductivity and the concentration of K+ ions in the flowing water. The aim is to distinguish between old and new water flow in the closing profile of a small mountain basin. As new water is called water, which was in contact with the soil only a short time - several minutes or hours. The term old water refers to water that was retained in the soil for many days or weeks. In the growing season, the K+ concentration in soil water decreases with the duration of contact of water with soil and plant roots, thus the K+ concentration in the water is an indicator of its age,ie. of the length of the delay of water in the soil.
Design of early warning system against lightning floods in mountain conditions
Tesař, Miroslav ; Šír, Miloslav ; Polívka, Jiří
The sophisticated local warning system against flash floods in mountain conditions is described. It is designed using the latest knowledge on the hydrodynamic mechanisms of storm runoff. It was found that extreme discharges are caused by these factors and their combinations: (1) saturation of soil cover with water, (2) soil surface hydrophobia, (3) gravity destabilized flow of water in the soil, (4) extreme rainfall, usually after prolonged dry period. Typical combinations causing extreme runoff, are (1) and (3) - the water saturation of soil cover can cause gravity destabilized flow induced by a small rain, (2) and (4) - long-term drought may cause the hydrophobic surface of the soil and simultaneously trigger extreme rain.
Hydrology of a small basin 2011
Šír, Miloslav ; Tesař, Miroslav
The book includes the full text of 73 scientific articles. These articles were prepared as the contributions for the Conference with international participation “Hydrology of a small basin 2011” that was held from March 8th to March 10th 2011 in Prague. The Conference was organized by the Institute of Hydrodynamics ASCR in Prague, Institute of Hydrology SAS in Bratislava, the Czech Water Management Society in Prague and Czech Committee for Hydrology. The book was published by the Institute of Hydrodynamics ASCR in Prague in 2011.
Hydrology of small watershed 2005
Šír, Miloslav ; Lichner, Ľ. ; Tesař, Miroslav ; Holko, L.
The book includes the full text of 48 scientific articles. These articles were prepared as the contributions for the Conference with international participation “Hydrology of a small basin 2011” that was held from September 14th to September 15th 2005 in Prague. The Conference was organized by the Institute of Hydrodynamics ASCR, v.v.i. in Prague; Institute of Hydrology SAS in Bratislava; the Czech Water Management Society in Prague and Czech Committee for Hydrology. The book was published by the Institute of Hydrodynamics ASCR, v.v.i. in Prague in 2005.
Hydrology of small basin 2008
Šír, Miloslav ; Tesař, Miroslav ; Lichner, Ľ.
The book includes the full text of 48 scientific articles. These articles were prepared as the contributions for the Conference with international participation “Hydrology of a small basin 2011” that was held from April 23th to April 24th 2008 in Prague. The Conference was organized by the Institute of Hydrodynamics ASCR, v.v.i. in Prague; Institute of Hydrology SAS in Bratislava; the Czech Water Management Society in Prague and Czech Committee for Hydrology. The book was published by the Institute of Hydrodynamics ASCR, v.v.i. in Prague in 2008.
New suspect in the investigation into the cause of flash floods
Bíl, M. ; Fürst, T. ; Vodák, R. ; Pražák, Josef ; Šír, Miloslav ; Tesař, Miroslav
The aim of this contribution is to introduce a new possibility of the description of unsaturated porous media flow. The approach presented here is entirely different from the traditional ways (e.g. the Richards‘ Equation). It will be explained why the traditional models often fail to describe various observed phenomena. The new approach provides certain interesting forecasts, among others a possible mechanism for flash-flood formation. The authors explain why they think that, under specific conditions, porous medium discharge may substantially exceed the infiltration due to rainfall.
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.
Hydrograph separation using ionic concentration measurement
Vondrka, A. ; Šír, Miloslav ; Tesař, Miroslav
In this article a method of hydrograph separation based on ionic concentration measurement is discussed. The goal of the method described is to distinguish the “old” and “new” water flowing in a stream in the closing profile of a small mountainous catchment. The “new water” is the rain water or the soil water which contact with the soil has a very short duration, a few minutes or hours. The term “old water” denotes water which was stored in the soil cover for many days or weeks. The Na+ and K+ ions will be used as the tracers distinguishing the “old” and “new” water. Namely, it is known that the concentration of the K+ ion in the soil water is decreasing according the growing duration of the contact of water with soil and plants roots. Ionic concentration will be measured with the help of ion selective electrodes. Two and three component separation algorithm will be used for the hydrograph separation.
Formation of extreme rains in the Krkonoše Mts. in summer 2002 and 2006
Tesař, Miroslav ; Šír, Miloslav ; Fišák, Jaroslav
In the article, hydrological and meteorological conditions preceding two extreme rains in the Krkonoše Mts. in summer 2002 and 2006 are discussed. Both were caused by cyclones, which moved from Hungary to Poland. Meteorological conditions preceding the rains were very similar in both cases – long-lasting lack of precipitation and extraordinary high air temperatures. We analyze the role of insufficient plant transpiration in the rise of both extreme rains.
Hydrologic extremes and gross primary productivity in the Liz catchment
Šír, Miloslav ; Tesař, Miroslav ; Lichner, Ľ. ; Váchala, J. ; Krejča, M.
The synergy between hydrologic extremes, plant transpiration, gross primary productivity, and soil water retention was studied in the experimental area Zábrod – meadow in the Bohemian Forest. Heat balance, potential and actual transpiration, entropy production and gross primary productivity were evaluated. It was found that the soil water retention is the crucial factor determining hydrologic pattern and gross primary productivity. Insufficient soil water retention leads to small entropy production by evaporation and small gross primary productivity, which results in the extremalization of the hydrologic cycle. On the other hand, in the case of sufficient soil water retention, high entropy production by transpiration and high gross primary productivity leads to the stability of the hydrologic cycle.

National Repository of Grey Literature : 62 records found   previous11 - 20nextend  jump to record:
See also: similar author names
1 ŠÍR, Martin
2 Šír, M.
5 Šír, Michal
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