Topsoil field-saturated hydraulic conductivity, Kfs, is a parameter that controls the partition of rainfall between
infiltration and runoff and is a key parameter in most distributed hydrological models. There is a mismatch between the
scale of local in situ Kfs measurements and the scale at which the parameter is required in models for regional mapping.
Therefore methods for extrapolating local Kfs values to larger mapping units are required. The paper explores the feasibility
of mapping Kfs in the Cévennes-Vivarais region, in south-east France, using more easily available GIS data
concerning geology and land cover. Our analysis makes uses of a data set from infiltration measurements performed in
the area and its vicinity for more than ten years. The data set is composed of Kfs derived from infiltration measurements
performed using various methods: Guelph permeameters, double ring and single ring infiltrotrometers and tension infiltrometers.
The different methods resulted in a large variation in Kfs up to several orders of magnitude. A method is proposed
to pool the data from the different infiltration methods to create an equivalent set of Kfs. Statistical tests showed
significant differences in Kfs distributions in function of different geological formations and land cover. Thus the mapping
of Kfs at regional scale was based on geological formations and land cover. This map was compared to a map based
on the Rawls and Brakensiek (RB) pedotransfer function (mainly based on texture) and the two maps showed very different
patterns. The RB values did not fit observed equivalent Kfs at the local scale, highlighting that soil texture alone is
not a good predictor of Kfs.
A series of maps showing the level of invasion of the Czech Republic by alien plants was developed based on a quantitative assessment of the level of invasion of 35 terrestrial habitat types at different altitudes. The levels of invasion were quantified for 18,798 vegetation plots, using two measures: proportion of the species that are aliens and total cover of alien species. Separate assessments were made for archaeophytes and neophytes. Within each habitat, the level of invasion was related to altitude using generalized linear models. The level of invasion, depending on the measure used, decreased with altitude in 16 out of 20 habitats for archaeophytes and 18 out of 23 for neophytes. In two habitats, one measure of the level of invasion increased with altitude for archaeophytes. The values of the level of invasion predicted by generalized linear models for particular combinations of habitats and altitudes were projected onto a land-cover map and digital elevation map of the country. Four maps showing the level of invasion were produced, based on the proportion of the species that are archaeophytes or neophytes, and cover of archaeophytes and neophytes. The maps show that both archaeophytes and neophytes are most common in lowland agricultural and urban areas, whereas they are sparsely represented in mountainous areas. At middle altitudes, agricultural areas are more invaded than forested areas. Outside agricultural and urban areas, high levels of invasion are found especially in lowland sandy areas and river corridors.
The study presented herein investigates the impact of simulated changes in land cover on rainfall-runoff conditions for the transboundary basin of the upper Lužnice. The HEC-HMS hydrological model was chosen for these simulations. Scenario models were used to simulate the impact of modifications in basin land cover with individual scenarios reflecting ground cover changes. The years 1990 and 2000, which are available in the CORINE Landcover database, were chosen as variants of river basin land cover. In addition, two theoretical versions of possible extreme variants in fundamental land cover changes - the conversion from agricultural land to grassland and the forestation of the river basin, with the exception of roads and bodies of water - were also included. Single day rainfall totals with a recurrence period of 10, 20, 50 and 100 years were selected to calculate the volume of runoff and culmination discharge. These results demonstrate a clear decrease in the degree of impact of land cover structure on runoff conditions, increasing with the magnitude of precipitation. and Článek představuje výsledky simulace vlivu změn krajinného krytu na srážko-odtokové poměry v přeshraničním povodí horní Lužnice. Pro modelování byl vybrán hydrologický model HEC-HMS. K modelování vlivu změn krajinného pokryvu povodí byla použita metoda scénářového modelování, kde se v jednotlivých scénářích mění krajinný pokryv. Jako varianty krajinného pokryvu povodí byly zvoleny roky 1990 a 2000, pro které je k dispozici databáze CORINE Landcover, a dále dvě teoretické krajní varianty možných variant změn struktury krajinného krytu - zatravnění zemědělské půdy a zalesnění povodí kromě intravilánů, komunikací a vodních ploch. Pro výpočet objemů odtoků a kulminačních průtoků byly vybrány jednodenní návrhové srážkové úhrny s pravděpodobností opakování 10, 20, 50 a 100 let. Z výsledků simulace je zřejmý pokles vlivu struktury krajinného pokryvu na odtokové poměry se vzrůstající extremitou srážky.