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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.
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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.
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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.
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Vliv vegetace na tepelnou bilanci a výměnu entropie
Šír, Miloslav ; Weger, J. ; Tesař, Miroslav ; Lichner, Ľ.
The aim of this study is to quantify the synergy between the vegetation cover, solar radiation, air temperature and soil moisture. Heat balance, potential and actual transpiration, and net entropy exchange at three localities under different plant cover was studied in order to determine crucial factors determining phytomass productivity in cold climatic areas of Bohemian Forest. The phytomass productivity can be quantified by the entropy exchange associated with the latent heat flux. Water shortage is a crucial factor determining phytomass productivity in dry and warm seasons in cold climatic conditions of Czech mountains.
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Wind drifted snow influence on the water balance in the catchment “Modrý potok”, the Giant Mountains, Czech Republic
Dvořák, I.J. ; Tesař, Miroslav ; Harčarik, J.
There are very specific components of the water balance in the mountain headwater regions. Beside the point of cloud- and fog-water deposition it is mainly accumulation of water in the snow cover drifted in the watershed by the wind. To get more realistic data, two digital models using cinematic carrier phase-based GPS measurements were developed: a model for snow surface data and the one for the underlying snow free ground surface. These two models have identified snow depths. The objective of this study is to highlight water storage in the snow-beds and show the GPS cinematic measurements as a contribution to best insight the snow accumulating and melting processes in the Modrý potok basin in the Giant Mts.
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Comparison of two models of forest transpiration
Šír, Miloslav ; Čermák, J. ; Naděždina, N. ; Naděždin, V. ; Tesař, Miroslav
Two transpiration models were tested in the paper, one is with plant control, and another without plant control. Principle of the (1) model with plant control was, that physical mechanism of transpiration is evaporation actively controlled by plants. The supposed mechanism is: part of the heat (heat equivalent of the energy absorbed from solar radiation), which would cause overheating the plant above 25 ºC is dissipated by evaporation. The model has five physical parameters, which are in principle measurable. (2) The model without plant control is based on the assumption, that transpiration dissipates a constant fraction of the heat from the heat equivalent of absorbed solar radiation (about 45 %). The model needs only one measurable physical parameter. Both models were tested by comparing their results with results actually measured daily totals of transpiration (via sap flow) in the floodplain forest Pohansko (near the town of Břeclav, southernmost Moravia), which was typical with almost non-limiting soil water supply over the period May 1 to Sept. 30, 1998. Results of both models were almost equal. We discussed their physical differences evaluating their goals and weak points and specified a program for further testing the physical mechanism of transpiration.
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