|
|
Use of uranine-probe method to determine evaporation rate from porous media
Pohan, Tomáš ; Slavík, Martin (advisor) ; Mareš, Jakub (referee)
Evaporation from porous media affects many natural processes. In my work, I focused on the second evaporation phase, calculating the evaporation rate using Fick's law based on air temperature and air humidity above the surface, the water-vapor permeability of the porous material, and the evaporation front depth below the surface. To determine this depth, I used the uranine-probe method using sodium fluorescein. The work aimed to calculate the evaporation rate using Fick's law and values of the evaporation front depth determined by the uranine-probe, for 6 sandy soil samples and 3 types of rocks. A sub-goal was to verify the applicability of the uranine-probe for determining the depth of the evaporation front in sandy soil and in 12 different rock samples. Results show successful determination of evaporation front depth for both sand and rocks. The uranine-probe method's accuracy averaged 2.0 mm for sand. The difference in the values determined by the uranine-probe method compared to another, independent method (detection of the evaporation front from the color change of the fluorescein solution) in the sand was on average 1.7 mm, but I did not study this for the rock samples. All evaporation experiments confirmed that the evaporation rate, both measured and calculated, decrease with increasing depth...
|
|
|
Soil evaporation and its controlling factors
Fröhlich, Lukáš ; Slavík, Martin (advisor) ; Mareš, Jakub (referee)
Evaporation is one of the basic members of water cycle, affecting a wide range of natural processes. The importance of the study of evaporation is even greater under conditions of climate change. This bachelor thesis focuses on soil evaporation and its controlling factors. The way in which water moves in porous media is described, and the terms evaporation, transpiration and evapotranspiration are defined. The division of the soil evaporation process into three phases is described and relative evaporation rates characteristic for the different phases are summarized. The relationship between evaporation and the spatial distribution of moisture inside soil is explained. The influence of internal and external factors on the evaporation rate is then described. It is assessed whether these factors contribute to higher or lower evaporation rates and under which conditions this occurs. It is evaluated whether the degree of influence of these factors is constant or whether it varies according to the circumstances and the evaporation phase in which the factors operate. Key words: evaporation, transpiration, evapotranspiration, evaporation phases, flow of underground water, external and internal factors of evaporation
|
guest ::
