Abstract:The assessment of the soil redistribution and real long-term soil degradation due to erosion on agriculture land is still insufficient in spite of being essential for soil conservation policy. Imaging spectroscopy has been recognized as a suitable tool for soil erosion assessment in recent years. In our study, we bring an approach for assessment of soil degradation by erosion by means of determining soil erosion classes representing soils differently influenced by erosion impact. The adopted methods include extensive field sampling, laboratory analysis, predictive modelling of selected soil surface properties using aerial hyperspectral data and the digital elevation model and fuzzy classification. Different multivariate regression techniques (Partial Least Square, Support Vector Machine, Random forest and Artificial neural network) were applied in the predictive modelling of soil properties. The properties with satisfying performance (R 2 > 0.5) were used as input data in erosion classes determination by fuzzy C-means classification method. The study was performed at four study sites about 1 km 2 large representing the most extensive soil units of the agricultural land in the Czech Republic (Chernozems and Luvisols on loess and Cambisols and Stagnosols on crystalline rocks). The influence of site-specific conditions on prediction of soil properties and classification of erosion classes was assessed. The prediction accuracy (R 2 ) of the best performing models predicting the soil properties varies in range 0.8-0.91 for soil organic carbon content, 0.21-0.67 for sand content, 0.4-0.92 for silt content, 0.38-0.89 for clay content, 0.73-089 for Fe ox , 0.59-0.78 for F ed and 0.82 for CaCO 3 . The performance and suitability of different properties for erosion classes' classification are highly variable at the study sites. Soil organic carbon was the most frequently used as the erosion classes' predictor, while the textural classes showed lower applicability. The presented approach was successfully applied in Chernozem and Luvisol loess regions where the erosion classes were assessed with a good overall accuracy (82% and 67%, respectively). The model performance in two Cambisol/Stagnosol regions was rather poor (51%-52%). The results showed that the presented method can be directly and with a good performance applied in pedologically and geologically homogeneous areas. The sites with heterogeneous structure of the soil cover and parent material will require more precise local-fitted models and use of further auxiliary information such as terrain or geological data. The future application of presented approach at a regional scale promises to produce valuable data on actual soil degradation by erosion usable for soil conservation policy purposes.

Water erosion is identified as the most severe type of soil degradation in the Czech Republic. Systematic protection preventing water erosion is not carried out in large areas of agricultural land. The map of the maximum tolerable CP factor value (the cover-management and the support-practice factors) -CP max was compiled in order to assess erosion hazard on agricultural land. It estimates the requirements of the conservation practices which would not cause soil erosion above the tolerable limit of annual soil loss. The map is based on calculations using an adjusted Universal Soil Loss Equation (USLE) and is easy to apply. It has already been applied in the Czech Republic when creating the map of erosion vulnerability for the purposes of delimitation of Standards of Good Agricultural and Environmental Conditions (GAECs), within Cross Compliance. The map covers the whole territory of the Czech Republic (scale 1:1,000,000).

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A careful analysis of rainfall-runoff events and patterns of sediment and pollution load to water bodies is crucial for the proper management of agricultural land. This study simultaneously employed the WaTEM/SEDEM long-term erosion model and the HEC-HMS episodic hydrological and erosion model to describe the runoff and sediment load evoked by extreme rainfall events in a small agricultural catchment in Czechia, using the long-term monitoring discharge and water quality episodic data. WaTEM/SEDEM helped to delineate the runoff and sediment critical source areas, subsequently incorporated into HEC-HMS. The acquired results showed that the spatial distribution of land use is a fundamental factor in the protection of watercourses from diffuse pollution sources and the transport and delivery of sediment profoundly depends on the status of crop cover on arable land near a watercourse. Integrating both models, it was shown that the tabulated Curve Number (CN) values as well as the average C-factor values had to be lowered for the majority of the modelled events to match the monitored data. A noticeable role of catchment runoff response most probably played tile drainage, which appeared to profoundly modify the episodic runoff pattern. This study showed a promising approach for the simulation of different rainfall-runoff responses of small agricultural catchments and could be applied for the delineation of areas where soil conservation measures or protective management is of high priority. The results further revealed the obvious need to revise the CN values for tile-drained catchments.

Kadlec V., Žížala D., Novotný I., Heřmanovská D., Kapička J., Tippl M.: Land consolidations as an effective instrument in soil conservation. Ekológia (Bratislava), Vol. 33, No. 2, p. 188-200, 2014.In the Czech Republic, more than 50% of agricultural land is threatened by water erosion, which is tremendously increasing during last couple of years. Therefore, it is necessary to deal with soil conservation as soon as possible. Land consolidations (LCs) are thus an important tool for implementation of soil, water and landscape conservation measures. It is possible to arrange land ownerships by them. They also arrange land spatially and functionally, provide availability of parcels and their land use in public interest. Besides that, environmental improvement, soil conservation, water management and increase in landscape ecological stability supplement the use of LCs. The results of soil consolidations serve for renewal of cadastral records and for the backgrounds for landscape planning. The aim of the research was to evaluate the selected site (district Plzeň - South) with regard to the amounts and limits of proposed and implemented measures in LC process. The research was processed on the basis of detailed analysis regarding erosion risk and runoff conditions in GIS compared with the previous data (before LC).