|
|
Crop water stress assessment using remote sensing approach
ERBEN, Jiří
The present thesis deals with evaluation of crop water stress by means of remote sensing. The first part of the research is focused on the assessment of water stress of sunflowers in a laboratory environment using spectral analysis of the reflected radiation and thermography. Leaf of suflowers temperature were evaluated and using them, the index of water stress CWSI were calculated. Reflection of leaf was evaluated in the wavelengths 350 -2500 nm. From these wavelengths spectral indexes were calculated - NDVI (Normalized difference vegetation index) which detect the presence of living green vegetation, WI (Water Index) which serve to calculate the approximate amount of water in the vegetation and RVI (simple ratio vegetation index) which determine the content of biomass or photosynthetic capacity. After that, they were compared with CWSI. Finally CWSI was compared with the spectral data, and from the resulting correlations they were apparent wavelengths, which correlated with given index more or less. The second part is focused on the assessment of water stress in terms of 4th. level catchment, specifically on catchment "Dehtáře" near Pelhřimov. There were primarily evaluated three biggest areas - fields of winter wheat, field corn and TTP.
|
|
|
Microclimate and energy balance characteristics of the stands with different management
ERBEN, Jiří
The present thesis deals with the microclimate and energy balance indicators of 2 habitats with different types of vegetation (wetland, pasture) during the growing season. Mainly moisture and temperature regime and energy fluxes were monitored in the period of 1.4. to 30.9., 2014. All values were dependent on the type of vegetation, and the type and location of the environment. Microclimate analysis was performed on two locations - in a pasture in the basin of Mlýnský stream and wetland habitat in the basin of Horský stream. Both sites are located on the right bank of the Lipno lake. All the necessary meteorological characteristics were measured using automatic weather stations. Indicators of temperatures and humidity of soil and air, received, and the total amount of reflected sunlight and heat balance characteristics - albedo, Bowen ratio, evaporative fraction and heat flows were evaluated. The biggest differences were monitored at heights, in which was measured. In terms of relative humidity, values most varied at canopy level, where the differences were noticeable. The highest mean relative humidity was measured at height of 0.2 m and 2 m on the wetland. As relative humidity even air temperature is dependent on the height at which it was measured. While the height of 2 m, the values at both sites was almost identical, at the canopy level are differences significant. The average temperature values depend on the season, but the largest amplitude of the temperature reached the sites in June. The surface temperature of the soil at the wetland was almost unchanged, contrary to pasture its course was similar to air temperatures series at the canopy level. The soil temperature at 20 cm was almost the same at both sites. In terms of energy fluxes, it was found that the highest latent heat flux of evaporation was in wetland. Sensible heat flux was higher in the pasture. The flux of heat into the ground is bigger during the morning and evening hours on the wetland, however ground heat flux was higher in the pasture during the day.
|
guest ::
RSS feed.