In the Czech Republic, the Universal Soil Loss Equation provides the basis for defining the soil protection strategy. Field rainfall simulators were used to define the actual cover-management factor values of the most extensively seeded crops in the Czech Republic. The second purpose was to assess rainfall-runoff ratio for different crops and management to contribute to the debate of water retention effectiveness during approaching climate change. The methodology focused on multi-seasonal measurements to cover the most important phenological phases. The rainfall intensity was 60 mm·h−1 for 30 min and a plot size of 16 m2. More than 380 rainfall simulation experiments provided data. Soil conservation techniques proved to have a significant effect on runoff reduction. Conventionally seeded maize can reduce the runoff ratio to around 50%. However, cover crops combined with reduced tillage or direct seeding can reduce the runoff ratio to 10–20% for ‘dry’ conditions and to 12–40% for ‘saturated’ conditions. Conventionally seeded maize on average loses 4.3 Mg·ha−1 per 30 min experiment. However, reduced tillage and direct seeding reduce soil loss to 0.6 and 0.16 Mg·ha−1, respectively. A comparison with the original USDA values for maize showed that it is desirable to redefine the crop cover factor.

Every application of soil erosion models brings the need of proper parametrization, i.e., finding physically or conceptually plausible parameter values that allow a model to reproduce measured values. No universal approach for model parametrization, calibration and validation exists, as it depends on the model, spatial and temporal resolution and the nature of the datasets used. We explored some existing options for parametrization, calibration and validation for erosion modelling exemplary with a specific dataset and modelling approach. A modified version of the Morgan-Morgan-Finney (MMF) model was selected, representing a balanced position between physically-based and empirical modelling approaches. The resulting calculator for soil erosion (CASE) model works in a spatially distributed way on the timescale of individual rainfall events. A dataset of 142 high-intensity rainfall experiments in Central Europe (AT, HU, IT, CZ), covering various slopes, soil types and experimental designs was used for calibration and validation with a modified Monte-Carlo approach. Subsequently, model parameter values were compared to parameter values obtained by alternative methods (measurements, pedotransfer functions, literature data). The model reproduced runoff and soil loss of the dataset in the validation setting with R of 0.89 and 0.76, respectively. Satisfactory agreement for the water phase was found, with calibrated saturated hydraulic conductivity (k ) values falling within the interquartile range of k predicted with 14 different PTFs, or being within one order of magnitude. The chosen approach also well reflected specific experimental setups contained in the dataset dealing with the effects of consecutive rainfall and different soil water conditions. For the sediment phase of the tested model agreement between calibrated cohesion, literature values and field measurements were only partially in line. For future applications of similar model applications or datasets, the obtained parameter combinations as well as the explored methods for deriving them may provide guidance.

<p>Vineyards are vulnerable to soill loss due to the several inherent factors highly discussed in the literature. A lot of research is being carried out on this topic and hundreds of experiments were conducted around the world in past decades. The use of rainfall simulators is very extensive with prominent results; however, the use of different scales is scarce in exact places but using different plot sizes. Small (1-4 m<sup>2</sup>) and big plots (>4 m<sup>2</sup>) can detect the initiation of specific processes such as surface runoff and initial of soill particle detachment. However, mechanisms such as connectivity, sedimentation or linear erosion differ among plot sizes. Also, the size, high water consumption and time-consuming of the big rainfall simulator makes its use something scarce. Therefore, the main goal of this research was to compare the big and small rainfall simulators and the obtained results considering the continuous development of various rainfall simulators on the CTU’s Department of Landscape Water Management (Prague, Czech Republic). The small rainfall simulator with 1x1 m plot and the big one covering two experimental plots of 8x1 m size were used next to each other in a conventional vineyard in the viticultural region of Moravia. The results showed different processes both of them key to understand from a holistic point of view the inititaion of soil erosion processes in vineyards.</p><p>This study has been supported by the Grant Agency of the Czech Technical University in Prague, grant No. SGS20/156/OHK1/3T/11 and the Project QK1910029.</p>

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