Maciej Liro

<p>Information on the transport and deposition of riverine macroplastic is crucial for selecting proper locations for river cleaning actions and for trapping infrastructure installation. Obtaining such information for mountain rivers is of particular importance because their specific characteristics make them particularly prone to illegal dumping, plastic litter input from slope to the river channel, and an increased rate of secondary microplastic production in the river channel (<strong>1</strong>).</p> <p>To shed some light on the patterns of macroplastic transport and deposition along mountain rivers we have performed a field experiment utilizing tracked plastic (PET) bottles injected to the channel of the mountainous Skawa River in the Polish Carpathians. After 50-57 days of low-flow conditions, we documented transport distances (<em>n</em>=64) which were non-normally distributed and reached from 0.37 km to 16.27 km (median=1.73 km, quartile range=5.29 km). Most of the tracked bottles were deposited on woody debris (71.9%,<em> n</em>=46) (Photo 1) at elevations ranging from 0 to 1.2 m (median=0.4 m, quartile range=0.45 m) above the low-flow water level. Surprisingly, the straight and narrow channelized reach of the studied river trapped 15.3 % of the plastic bottles transported through it, while the highly sinuous, wide unregulated one only 8.7 %, which is probably related to the more frequent contact of woody debris (present in both reaches) with the flowing water, occurring during low-flow conditions within the narrower, channelized reach.</p> <p>Our initial results suggest that places of woody debris deposition along rivers can be a good location for river cleaning actions. </p> <p><img src="" alt="" /></p> <p><strong>Photo 1</strong>. The deposition of plastic bottles on wood jam<br />(the Skawa River, S Poland) (photo by M. Liro)</p> <p> </p> <p>References</p> <p><strong>(1) </strong>Liro, M., van Emmerik, T.H., Zielonka, A., Gallitelli, L., Mihai, F.C., 2023. The unknown fate of macroplastic in mountain river. <em><strong>Sci. Total Environ</strong></em>. <em>865, 161224.</em></p>

Plastic waste poses numerous risks to mountain river ecosystems due to their high biodiversity and specific physical characteristics. Here, we provide a baseline assessment for future evaluation of such risks in the Carpathians, one of the most biodiverse mountain ranges in East-Central Europe. We used high-resolution river network and mismanaged plastic waste (MPW) databases to map MPW along the 175,675 km of watercourses draining this ecoregion. We explored MPW levels as a function of altitude, stream order, river basin, country, and type of nature conservation in a given area. The Carpathian watercourses below 750 m a.s.l. (142,282 km, 81 % of the stream lengths) are identified as significantly affected by MPW. Most MPW hotspots (>409.7 t/yr/km2) occur along rivers in Romania (6568 km; 56.6 % of all hotspot lengths), Hungary (2679 km; 23.1 %), and Ukraine (1914 km; 16.5 %). The majority of the river sections flowing through the areas with negligible MPW (< 1 t/yr/km2) occur in Romania (31,855 km; 47.8 %), Slovakia (14,577 km; 21.9 %), and Ukraine (7492; 11.2 %). The Carpathian watercourses flowing through the areas protected at national level (3988 km; 2.3 % of all watercourses studied) have significantly higher MPW values (median = 7.7 t/yr/km2) than those protected at regional (51,800 km; 29.5 %) (median MPW = 1.25 t/yrkm2) and international levels (66 km; 0.04 %) (median MPW = 0 t/yr/km2). Rivers within the Black Sea basin (88.3 % of all studied watercourses) have significantly higher MPW (median = 5.1 t/yr/km2, 90th percentile = 381.1 t/yr/km2) than those within the Baltic Sea basin (median = 6.5 t/yr/km2, 90th percentile = 84.8 t/yr/km2) (11.1 % of all studied watercourses). Our study indicates the locations and extent of riverine MPW hotspots in the Carpathian Ecoregion, which can support future collaborations between scientists, engineers, governments, and citizens to better manage plastic pollution in this region.

Mountain rivers are typically seen as relatively pristine ecosystems, supporting numerous goods (e.g., water resources) for human populations living not only in the mountain regions but also downstream from them. Recent evidence suggests, however, that mountain river valleys in populated areas can be substantially polluted by macroplastic (plastic item > 5 mm). It is, however, unknown how distinct characteristics of mountain rivers modulate macroplastic routes through them, which makes planning effective mitigation strategies difficult. To stimulate future works on this gap, here, we present a conceptual model of macroplastic transport pathways through mountain river. Based on this model, we formulate four hypotheses on macroplastic input, transport and degradation in mountain rivers. Then, we propose designs of field experiments that allow each hypothesis to be tested. We hypothesize that some natural characteristics of mountain river catchments (e.g., steep valley slopes, mass ...

Macroplastic pollution in mountain rivers can threaten water resources, biodiversity, and the recreational values provided by them. The first step towards evaluating and then mitigating these risks is the systematic collection of reliable and spatially uniform data on the amount and type of macroplastics deposited in different land covers occurring in a mountain river channel. To maximise the opportunity for the large-scale collection of such data using the citizen science approach, we propose in this study an illustrated step-by-step guide to sample the macroplastic deposited along mountain rivers and to record the collected information using a photo taken by smartphone and a simple online form. Our guide includes three steps: (i) the location of sampling plots across 3–4 predefined surface covers occurring in mountain rivers of temperate climate, (ii) the hand collection of macroplastic deposited in them, and (iii) the photorecording and archiving of information on macroplastics c...

The water depth and flow velocity of a river may be temporarily disturbed by the water level fluctuations connected with the operation of artificial dam reservoirs located downstream (so-called backwater fluctuations (BF)). In this research, we use the two-dimensional hydrodynamic model iRIC MFlow_02 to quantify the effects of BF on the lowermost section (ca. 1.5-km length) of a small (channel width ≤ 20 m) mountain stream, the Smolnik Stream, which flows into the Rożnów Dam Reservoir, in Southern Poland. To reproduce the hydrological conditions generally observed in the stream, six scenarios were simulated, considering three steady flow discharges at the inlet, with recurrence intervals of 1 year (1.8 m3 s−1, small flood), 2 years (24.5 m3 s−1; medium flood), and 20 years (89.5 m3 s−1; large flood), and two reservoir levels at the outlet: 265 m a.s.l. (normal reservoir water level) and 270 m a.s.l. (maximum reservoir water level). In these simulations, sediment transport and morpho...

<p>Amounts of macroplastic debris stored on different elements of mountain rivers are unknown, but such data are crucial to plan future mitigation activities in these fragile ecosystems. We determined the amounts of macroplastic stored on different surface types (geomorphic units and wood jams) in two reaches of the Dunajec River in the Polish Carpathians. A wide, multi-thread reach stored 36 times more macroplastic per 1 km of river length than the upstream-located narrow, channelized reach (1495.4 kg vs. 41.8 kg). In the multi-thread reach, 43.8% and 41.1% of macroplastic was stored on wooded islands and wood jams that covered, respectively, 16.7% and 1.5% of the area of active river zone. The median of macroplastic mass stored on wood jams equalled 113.2 g/m<sup>2</sup> and was 180 times higher than on exposed river sediments, 129 times higher than in the areas overgrown with herbaceous vegetation and 19 times higher than on wooded islands. The results indicated that multi-thread reaches of mountain rivers supporting extensive wooded islands and numerous wood jams are hot-spots of macroplastic storage, whereas channelized reaches lacking these surface types act as transport reaches for macroplastic debris. Thus, multi-thread reaches of mountain rivers in populated areas can be used as target zones for river cleaning actions and downstream ends of channelized reaches as the location for installation of macroplastic trapping infrastructure.</p>

Impact of channel regulation on sedimentation on the Lower Dunajec floodplains. Prz. Geol., 60: 380–386. A b s t r a c t. In the last century the Dunajec channel in its lower river course was considerably transformed due to channelization works. The former multi-thread river channel was replaced by a single one, resulting in abandonment of side channels. Groynes were constructed on both main and side channel. Quick filling up of the inter-groyne basins reduced channel width and capacity. In the study area, a side channel with groynes was abandoned and filled up. The aim of this study was to reconstruct the rate and depositional conditions of the sediments infilling the abandoned channel. These sediments are 215-222 cm thick and were deposited at an average rate of 5-5.2 cm/year. Their sedimentary environment was inferred based on a C/M diagram. The depositional conditions in the abandoned channel were determined by two major factors: distance to the active channel and difference in ...

<p>Subsurface erosion by soil piping is a widespread land degradation process that occurs in different soil types around the world. Recent studies have shown that piping erosion may lead to the significant soil loss and disturbances of ground surface. This process accelerates also gully erosion. However, it is still omitted in hydrological models of a catchment, as well as in soil and water erosion models. It seems that the main problem in soil piping studies lies on the basic issue, i.e., the detection of subsurface tunnels (soil pipes). As geophysical methods enable the exploration below the ground surface, they are promising in soil piping studies.</p><p> </p><p>This study aims to evaluate the suitability of the electromagnetic induction (EMI) to detect subsurface network of soil pipes. The detailed study was conducted in the small catchment (Cisowiec) in the Bieszczady Mts. (the Eastern Carpathians, SE Poland), where pipes develop in Cambisols. The measurements were carried out using a conductivity meter EM38-MK2 (Geonics) in both vertical and horizontal measuring dipole orientations. The EM38-MK2 provided simultaneous measurements of apparent electrical conductivity with two transmitter receiver coil separation (0.5 m and 1 m). In order to compare subsurface data with the surface response (i.e., depressions and collapses), the high resolution DEM and orthophotos have been produced. These data have been prepared using Structure from Motion (SfM) technique based on the images taken from the low altitude by an Unmanned Aerial Vehicle (UAV; DJI Phantom-4 equipped with a 1' camera). The UAV-derived products (orthophotos and DEM) have the resolution of 0.014 x 0.014 m and point density of 9240 per 1 m<sup>2</sup>.</p><p> </p><p>The EMI results are presented on the maps that gathered data at three depths (0.4 m, 0.75 m, 1.5 m). The results revealed the soil pipes as areas characterized by higher electrical conductivity than the surroundings. The spatial distribution of subsurface tunnels corresponds with the ground depressions and collapses detected in the field and seen on the high resolution DEM and orthophoto. The use of EMI in piping research has been evaluated.</p><p> </p><p>The study is supported by the National Science Centre, Poland within the first author’s project SONATINA 1 (2017/24/C/ST10/00114).</p>

The paper presents a conceptual model of the route of macroplastic debris (>5 mm) through a fluvial system, which can support future works on the overlooked processes of macroplastic storage and remobilization in rivers. We divided the macroplastic route into (1) input, (2) transport, (3) storage, (4) remobilization and (5) output phases. Phase 1 is mainly controlled by humans, phases 2–4 by fluvial processes, and phase 5 by both types of controls. We hypothesize that the natural characteristics of fluvial systems and their modification by dam reservoirs and flood embankments construction are key controls on macroplastic storage and remobilization in rivers. The zone of macroplastic storage can be defined as a river floodplain inundated since the beginning of widespread disposal of plastic waste to the environment in the 1960s and the remobilization zone as a part of the storage zone influenced by floodwaters and bank erosion. The amount of macroplastic in both zones can be estim...

Dam reservoir construction is one of the most important factors shaping river-valley morphology in the Anthropocene. While a large number (>58,000) of these constructions are in operation all over the world, we remain quite ignorant of what happens upstream of them (in so called backwater zone), especially for the case of gravel-bed rivers. Existing studies have shown that adjustments of the gravel-bed river in the backwater zone differ between the initial and long-term adjustments. The initial adjustments (occurring ≈ <20 years following dam construction) are controlled by large floods and in-channel deposition which trigger bi-directional bar↔bank interactions (bank erosion causing bar growth and vice versa) resulting in channel-widening. The long-term adjustments (≈ >20 years following dam construction) are characterized by river sinuosity increa sing and channel planform stabilization resulted from deposition of fine sediment and associated vegetation expansion. The lon...

Little is known on the planform evolution of gravel-bed rivers in base-level raised backwater zones upstream from dam reservoirs. The general model of river channel response to base-level rise predicts a decrease in river sinuosity. However, the observations of channel adjustments in the reservoir backwater document a narrower and more sinuous channel developed as a result of fine sediment deposition and vegetation expansion. Here, the long-term aerial photo-based observations (1963–2015) of two gravel-bed rivers of different initial channel pattern (the Dunajec and its tributary, the Smolnik) located in the base-level raised zone of the Rożnów Reservoir in the Polish Carpathians were analyzed. The results show that the initially multi-thread river in backwater was significantly narrowed and its sinuosity increased (phase 1), which was followed by the stabilization of channel planform (phase 2). However, in the initially single-thread river only phase 2 occurred. The rate of channel narrowing observed on the initially multi-thread river was positively related to the initial channel width (R 2 = 0.90, p b 0.0001) and bar width (R 2 = 0.81, p b 0.0001). The increase in sinuosity was higher in the previously wider channel section and did not occur in the valley-confined zones of the single-thread river. The results are conceptualized in a two-phase conceptual model, which hypothesizes that the trajectories of the long-term planform adjustments of gravel-bed river in backwater are controlled by the initial river morphology which creates accommodation space for fine sediment deposition and associated vegetation expansion.

Information on the magnitude of the measurement error is necessary to assess the magnitude of changes that may be identified during an analysis. In this paper, the impact of the aerial photo scale and the measurement scale in the GIS software on the magnitude of the digitization (identification) error of a river channel bank was analysed. Repeat digitization of the same channel bank carried out in aerial photographs differing in the scale (1:7,500–1:30,000) with different measurement scales (1:1,000–1:10,000) used on each of them, showed that increasing the scale used for digitizing in the GIS software decreased the magnitude of digitization errors much more than similar increasing the aerial photo scale. The results of the analysis show that the selection of an appropriate digitizing scale in GIS software is an important factor affecting measurement error. The discussion of the results indicates that in some cases the calculation of the digitization error based on the aerial photo scale or the arbitrarily assumed error value may be higher than the real error which has occurred during digitization. The results obtained showed that the product of 0.25 mm and the scale used for digitizing in GIS can be a good approximation of the digitizing error which occurred in the aerial photos taken at the scale range of 1:7,500–1:30,000

In the northern slope of the Carpathian Mountains and in their foreland, river and stream channels have been significantly transformed by human impact. These transformations result from changing land use in river basins and direct interference with river channels (alluvia extraction, engineering infrastructure, channel straightening). Anthropogenic impacts cause significant changes in the channel system patterns leading to increased impact of erosion. This mainly leads to the channelling of the fluvial system. This article reviews studies of structure and dynamics of Carpathian river channels conducted based on the methodology of collection of data on channel systems, developed in the Department of Geomorphology of the Institute of Geography and Spatial Management, Jagiellonian University.

The effects of base-level rising upstream of dam reservoirs on in-channel sedimentation and interaction of the stored sediments with the gravel-bed channel morphology have received little attention so far. Previous studies, however, suggested that the feedback mechanism between in-channel sedimentation and bank erosion may affect channel morphology. Here, the pattern of the bar area, bank erosion, and morphology of the gravel-bed Dunajec River upstream from the Czorsztyn Reservoir (CR), constructed in 1997 in southern Poland were analyzed from aerial images (1982–2012) and LiDAR data (2013). In the part of the post-dam period with a large flood, the average bar area increased significantly in the backwater section, and at some distance upstream, and then extended in the upstream direction at an average rate of above 40 m/y, reaching 2.2 km upstream from the CR in 2012. The bar area variation was 40% and 77% explained by local bank erosion in the periods of large and low to moderate floods, respectively. The sum of bank erosion from the post-dam period explained 80% of the variation in the present width/depth ratio, significantly increased in the backwater section. The results showed that the large floods in 1997, in conjunction with backwater inundation, initiated intensive bank erosion and bar growth. Subsequently, in the period with low and moderate floods, the localized bar-bank interaction, connected with the flow divergence around the deposited bar, led to localized bank erosion and additional bar growth promoting bend development. These processes, propagating in the upstream direction, were facilitated by the existence of a large amount of easily remobilized sediment stored in the floodplain connected with the sedimentation zone from the end of the nineteenth century. Bend development was controlled by valley confinement causing downstream bend translation in the narrower valley-confined section and its extension in the wider unconfined section of past sediment storage. The results obtained from this site-specific location imply that the occurrence of similar past sediment storage zones of easily remobilized coarse sediments may favor intensive bank erosion and bar growth during large floods, and in the case of low transport, competent backwater zones of gravel-bed rivers where the remobilized sediments cause localized bar growth; it may promote morphologically effective bar-bank interaction in the period with low and moderate floods

ABSTRACT Despite a significant increase in the number of dam reservoirs in the world in the last century, the effects of these structures on the evolution of river channels above them are poorly understood. Constructed in 1997 in the Polish Carpathians, the Czorsztyn Reservoir (CR) has raised the base level of the single-thread, gravel-bed Dunajec River. An analysis of five sets of aerial photographs and orthophotos from the period before (1977, 1982, 1994) and after (2003, 2009) the construction of the CR allowed me to investigate the temporal and spatial impact of the raised base level of the river upstream of the reservoir on the evolution of the river channel. Comparison of chan-nel width changes in the backwater river section with changes observed in the control section unaffected by the presence of the reservoir has shown that in the pre-dam period differences in the evolution of the river channel in the backwater section and in the control section were not statistically different. In the periods without major floods, both channel sections were dominated by channel narrowing or a relative stability of channel width. In the post-dam period, a major flood in 1997 caused more than two times greater channel widening in the back-water section than in the control section. The extent of channel widening in the longitudinal channel profile reached farther upstream of the reservoir than the extent of the backwater itself. In the later part of the post-dam period without major floods, channel narrowing were similar in the backwater section and the control section, as had been the case in the period before the reservoir construction. The comparison of changes in the width of the channel in the backwater and control sections indicates that channel widening in the backwater, interpreted as an early stage of backwater channel adjustment, was reinforced by the flood of 1997. This study shows that the use of a control section makes it possible to isolate reservoir effects from flood effects in the context of channel dynamics.