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Funding Information: Monika Barbara Kalinowska, Emilia Karamuz, and Michael Nones were supported within statutory activities no. 3841/E-41/S/2022 of the Ministry of Science and Higher Education of Poland. Adam Kiczko, Andrzej Brandyk, Adam Kozioł, and Marcin Krukowski were supported by the Polish National Centre for Research and Development (grant no. BIOSTRATEG3/347837/11/NCBR/2017). Kaisa Västilä was supported by Maa- ja vesitekniikan tuki ry (grant no. 33271) and the Academy of Finland (grant no. 330217). Funding Information: Monika Barbara Kalinowska, Emilia Karamuz, and Michael Nones were supported within statutory activities no. 3841/E-41/S/2022 of the Ministry of Science and Higher Education of Poland. Adam Kiczko, Andrzej Brandyk, Adam Kozioł, and Marcin Krukowski were supported by the Polish National Centre for Research and Development (grant no. BIOSTRATEG3/ 347837/11/NCBR/2017). Kaisa Västilä was supported by Maa- ja vesitekniikan tuki ry (grant no. 33271) and the Academy of Finland (grant no. 330217). Thanks to Łukasz Przyborowski from the Institute of Geophysics Polish Academy of Sciences, and Aesha Marsoumi and Shea Nee Chew from Warsaw University of Technology for helping with the field and laboratory measurements of rhodamine concentration. We appreciate comments from Steve Wallis, Paweł Rowi´nski, and an anonymous referee that contributed to the article’s improvement. Publisher Copyright: © 2023 Monika Barbara Kalinowska et al. In temperate climates, agricultural ditches are generally bounded by seasonal vegetation, which affects the hydrodynamics and mixing processes within the channel and acts as a buffer strip to reduce a load of pollutants coming from the surrounding cultivated fields. However, even if the control of such vegetation represents a key strategy to support sediment and nutrient management, the studies that investigated the effect of different vegetation maintenance scenarios or vegetation coverage on the flow and mixing dynamics at the reach scale are very limited. To overcome these limitations and provide additional insights into the involved processes, tracer tests were conducted in an agricultural ditch roughly 500gm long close to Warsaw in Poland, focusing on two different vegetation scenarios: highly vegetated and fully cut. Under the highly vegetated scenario, sub-reaches differing in surficial vegetation coverage are analysed separately to better understand the influence of the vegetation conditions on the flow and mixing parameters. Special attention has been paid to the longitudinal dispersion coefficient in complex natural conditions and its dependency on vegetation coverage (V). The vegetation maintenance decreased the travel and residence times of the solute by 3-5 times, moderately increasing the peak concentrations. We found that the dispersion coefficient decreased approximately linearly with the increase of vegetation coverage at V>68g%. Further research is needed at lower vegetation coverage values and different spatial plant distributions. The obtained longitudinal dispersion coefficient values complement dispersion value datasets previously published in the literature, which are barely available for small natural streams. The new process understanding supports the design of future investigations with more environmentally sound vegetation maintenance scenarios. |
