Reinforcing the small water cycle is considered to be a holistic approach to both water resource and landscape management. In an agricultural landscape, this can be accomplished by incorporating agricultural conservation practices; their incorporation can reduce surface runoff, increase infiltration, and increase the water holding capacity of a soil. Some typical agricultural conservation practices include: conservation tillage, contour farming, residue incorporation, and reducing field sizes; these efforts aim to keep both water and soil in the landscape. The incorporation of such practices has been extensively studied over the last 40 years. The Soil and Water Assessment Tool (SWAT) was used to model two basins in the Czech Republic (one at the farm-scale and a second at the management-scale) to determine the effects of agriculture conservation practice adoption at each scale. We found that at the farm-scale, contour farming was the most effective practice at reinforcing the small water cycle, followed by residue incorporation. At the management-scale, we found that the widespread incorporation of agricultural conservation practices significantly reinforced the small water cycle, but the relative scale and spatial distribution of their incorporation were not reflected in the SWAT scenario analysis. Individual farmers should be incentivized to adopt agricultural conservation practices, as these practices can have great effects at the farm-scale. At the management-scale, the spatial distribution of agricultural conservation practice adoption was not significant in this study, implying that managers should incentivize any adoption of such practices and that the small water cycle would be reinforced regardless.

In the face of future climate change, Europe has encouraged the adoption of biofuel crops by its farmers. Such land-use changes can have significant impacts on the water balance and hydrological behavior of a system. While the heavy pesticide use associated with biofuel crops has been extensively studied, the water balance impacts of these crops have been far less studied. We conducted scenario analyses using the Soil and Water Assessment Tool (SWAT) to determine the effects of farm-scale biofuel crop adoption (rapeseed) on a basin’s water balance. We found that rapeseed adoption does not support the goal of developing a sustainable agricultural landscape in the Czech Republic. The adoption of rapeseed also had disproportionate effects on a basin’s water balance depending on its location in the basin. Additionally, discharge (especially surface runoff ratios), evapotranspiration, and available soil water content display significant shifts in the rapeseed adoption scenarios.

The Czech landscape has undergone various changes over the last 100 years and has been mainly adapted agriculturally for economic purposes. This has resulted, among other things, in reservoirs being clogged with sediment. The Vrchlice Reservoir was built in 1970 to supply drinking water for around 50,000 inhabitants, and increased sedimentation has been detected in the reservoir in recent years. Water erosion and sediment transport were modeled with WaTEM/SEDEM. Sediment volumes were measured in eight ponds across the watershed for calibration purposes. Modeled results from ponds in watersheds covered mostly with arable lands generally corresponded with the measured values. Although in forested watersheds, the measured sediment volumes greatly exceeded modeled sediment yields, indicating high uncertainty in using USLE-based models in non-agricultural watersheds. The modeled scenarios represented pre-Communist, Communist, and post-Communist eras. For these periods WaTEM/SEDEM was used to evaluate three isolated effects: the effects of various crops on arable lands, the effects of farmland fragmentation, and finally the effects of changes in land use. The change in crops proved to be an important factor causing high siltation rate (potential 23% reduction in sediment yield for historical periods), and land fragmentation played the second important role (potential 15% reduction in sediment yield can be reached by land fragmentation). Across all scenarios, the lowest sediment yield and reservoirs siltation rates were obtained from the pre-Communist and Communist crop share under current land use conditions, and current land use with farmland fragmentation implemented, as it was re-constructed for the pre-Communist era. This supports the idea that the introduction of green areas within arable lands are beneficial to the landscape and can help reduce soil erosion and reservoir siltation.

For the Czech Republic to recover from the effects of past mismanagement, it is necessary to determine how its landscape management can be improved holistically by reinforcing the small water cycle. We conducted a scenario analysis across four time periods using SWAT (Soil and Water Assessment Tool) to determine the effects of land use, land management, and crop rotation shifts since the 1800s in what is now the Czech Republic. The 1852 and 1954 land-use scenarios behaved the most similarly hydrologically across all four scenarios, likely due to minimal landscape transformation and the fact that these two scenarios occur prior to the widespread incorporation of subsurface tile drainages across the landscape. Additionally, the crop rotation of 1920–1938 reinforces the small water cycle the most, while that of 1950–1989 reinforces the small water cycle the least. Diversified crop rotations should be incentivized to farmers, and increasing the areas of forest, brush, and permanent grassland should be prioritized to further reinforce the small water cycle. It is necessary to foster relationships and open communication between watershed managers, landowners, and scientists to improve the small water cycle and to pave the way for successful future hydrological modeling in the Czech Republic.

Inappropriate soil, water, and landscape management has decreased the water retention capacity of the landscape in the Czech Republic over time. Many sources of such mismanagement can be traced to an agricultural intensification across the Czech landscape that began after the 1953 collectivization process due to Communist Era policies. During this time large monotonous fields, subsurface tile drainage systems, and artificially straightened streams were incorporated across the landscape. Currently, much of the Czech agricultural landscape is managed by large conglomerates who prioritize profit over all else. Reinforcing the small water cycle is considered to be a holistic approach to water resource management within a landscape. Changes in land use and land management can greatly affect the water balance at a basin-scale. The objectives of this research are to calibrate and validate the Soil and Water Assessment Tool (SWAT) in the Czech landscape at two scales (the farm-scale and the management-scale) and to model various scenarios (e.g., crop changes, land use/management changes, and the incorporation of agricultural conservation practices) to determine management regimes that would reinforce the small water cycle. This research found that rapeseed adoption does not support the goal of developing a sustainable agricultural landscape in the Czech Republic. The adoption of rapeseed had disproportionate effects on a basin’s water balance depending on its location in the basin. In addition to crop changes, it was found that land use changes significantly affected the small water cycle at the basin-scale. Of the four land use change scenarios conducted (1852, 1954, 1983, and 2019), the 1852 and 1954 scenarios behaved the most similarly hydrologically, likely due to minimal landscape transformation and the fact that these two scenarios occur prior to the widespread incorporation of subsurface tile drainages across the landscape. Additionally, the crop rotation of 1920–1938 (Pre-Communist Era) reinforced the small water cycle the most, while that of 1950–1989 (Communist Era) reinforced the small water cycle the least. Regarding the incorporation of agricultural conservation practices at the farm-scale, SWAT modeled contour farming as the most effective practice that reinforced the small water cycle followed by residue incorporation. At the management-scale, the widespread incorporation of agricultural conservation practices significantly reinforced the small water cycle, but the relative scale and spatial distribution of their incorporation were not reflected in the SWAT scenario analysis.

The Czech Republic is an intensely agricultural country. Agricultural intensification of the Czech Republic started in the 1970s during the Communist regime wherein large monotonous agricultural fields, subsurface tile drainage systems, and artificially straightened streams were incorporated across the landscape. Since 1989 (the end of the Communist era), agricultural land and management has been privatized and has experienced shifts from centrally planned crop rotations to those that are economically-driven. On the other hand, nowadays many Czech farmers are beginning to explore various agricultural conservation practices which can have as significant of an impact as land use changes. The purpose of this study is to determine the effects of various agricultural conservation practices (contour tillage, reduced tillage, and grass strip addition) and decreasing field sizes at the farm scale in a representative agricultural basin in the Czech Republic. We conducted scenario analysis using the Soil and Water Assessment Tool (SWAT) to determine the effects of these measures on basin water balance and soil erosion. Through SWAT we were able to determine which measures are most effective when combined at the farm-scale.Acknowledgment: The presented research has been performed within project H2020 No. 773903 Shui, focused on water scarcity in European and Chinese cropping systems and the Grant Agency of Czech Technical University in Prague, No. SGS20/156/OHK1/3T/11.