Using WaTEM/SEDEM to Model the Effects of Crop Rotation and Changes in Land Use on Sediment Transport in the Vrchlice Watershed

Abstract

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.

Slowing Down Quick Runoff—A New Approach for the Delineation and Assessment of Critical Points, Contributing Areas, and Proposals of Measures to Reduce Non-Point Water Pollution from Agricultural Land

“…The model has been utilized (and calibrated) numerous times in the Czech Republic [12,53,54], with the parameters being tested and verified to suit the local conditions. The default parameters used in the study, based on the previously calibrated ones, are as follows: Ktc (low) = 35, Ktc (high) = 55, Ktc (limit) = 0.1; Ptef (cropland) = 0, Ptef (forest, pasture) = 75; parcel connectivity (cropland, forest, pasture) = 0, LS and nearing slope exponent [55], where Ktc represents the parameter of transport capacity, Ptef limits the non-arable-land areas, and parcel connectivity represents the border effect of neighboring parcels.…”

“…Regarding subsurface water, the main type of pollution is related to Water 2023, 15, 1247 2 of 21 land drainage systems [4][5][6]. Globally, the most significant pollutants present in surface and subsurface waters are pesticides [7,8], nitrates [9][10][11], phosphorus and suspended solids [12][13][14], and some micropollutants [15]. All these pollutants enter water bodies mainly in connection with rainfall-runoff events; in other words, runoff, and soil-water interactions and dynamics are the main drivers of pollutants transport from farmland to the surrounding waters [12,[16][17][18]; therefore, water treatment options used to ensure clean water suitable for drinking purposes are more difficult and costly to achieve [19].…”

Impacts of Land Use Conversion on Soil Erosion in the Urban Agglomeration on the Northern Slopes of the Tianshan Mountains

“…Scholars have proposed different methods for SDR estimation [16]. Consequently, several models, such as (R)USLE-SDR [17], WaTEM/SEDEM [18], and SEDD [19], have been developed in response to these efforts. In particular, the InVEST-SDR (integrated valuation of ecosystem services and tradeoffs-sediment delivery ratio) model integrates the USLE equation and the work of Borselli et al [20] and Vigiak et al [21] to determine the spatial distribution of sediment production within a catchment.…”