The paper evaluates the impact of river training works designed to address problems associated with flooding on the braided-wandering Belá River in Slovakian Carpathians. This impact was investigated ...after the flood event in July 2018 on 11 river reaches where the river engineering and management intervention was applied. We analyzed its impact by spatio-temporal variations in river morphology (12 channel parameters) and changes in cross-section and hydraulic parameters (flow velocity, shear stress, stream power, W/D ratio) between pre- and post-flood management periods. The research hypotheses related to decreasing geodiversity in managed river reaches, a rapid increase in flow velocity during an extreme flood in river reaches where there is no sufficient floodplain inundation due to artificially high banks built by river training works, and increasing erosive force in the channel zone thanks to river management intervention were confirmed. The intervention in the braidplain area of the Belá River resulted in an undesirable simplification of the river pattern, loss of geomorphic diversity, loss of channel-floodplain connectivity, and disturbance and restraint of hydromorphological continuity. Identification of main conflicts of the Belá River management is important for clarifying the different approaches of stakeholders in the study area and aims to provide an objective illustration of their consequences. The presented analyses could help in future management issues as well as in the more critical decision-making process in vulnerable and rare braided river systems on the present when we are losing so many natural rivers by human decisions.
Low water levels occurring on the Warsaw section of the Vistula River during droughts in 2012 and 2015 stirred considerable interest by exposing parts of the riverbed. The river's low flow discharge ...created favourable conditions for archaeologists who, from the river's bottom, managed to salvage sculptures, architectural artefacts, and military accessories dating back to the middle of the 17th century. Literature shows that archaeological finds at the bottom of a major lowland river are unique and are attributed to very specific hydrological and geological conditions. Embankments and works meant to regulate the channel of the Vistula River in Warsaw narrowed the channel and accelerated the erosion of the river's bottom. A comparison of rating curves created between 1919 and 2015 shows that the river's bottom had lowered by 225 cm. The diameter of sediment particles that could be moved at maximum shear stress has been calculated using the Meyer–Peter and Muller formula. According to the calculated shear stress corresponding to the highest historical flood of 1844 particles smaller than 0.05 m were transported down the river, and it is true that artefacts of that size had not been collected at the site. Taking into consideration the very specific geological and hydrological conditions, we believe that finding so many 17th century artefacts with a well‐documented history at a site at the bottom of major lowland river with intensive channel processes is indeed unique. Additionally, it is the first time that results of hydrodynamic modelling have been successfully used for archaeological survey to define the critical shear stress and the smallest diameter of artefacts, which could remain stable on a river's bottom.
The method based on original metric called Hydromorphological Index for Rivers (HIR) was developed in 2017 for the purpose of the monitoring of the hydromorphological status of flowing waters in ...Poland. It fulfils requirements of the EU Water Framework Directive (WFD). It allows assessment of both lowland rivers as well as mid-altitude and highland streams. The proposed system can be used to assess the natural and heavily modified rivers as well as artificial channels. The basis of the proposed system is a field survey, which is supplemented by analysis of Geographic Information Systems (GIS) data and remote sensing materials. Analysis of the GIS data and remote sensing materials already enable to estimate preliminary classification of hydromorphological status of non-surveyed water bodies. Basing on the field survey, the principal HIR value can be estimated for the considered river site and comparing with the reference conditions the hydromorphological quality status in the five-class system can be calculated. Properly selected, representative survey sites (one or more depending on the heterogeneity of the environment), enable classification and evaluation of entire surface water bodies in the framework of the national environmental monitoring. The GIS component of the HIR proved to be useful in verifying the determination of heavily modified water bodies and in assessing the needs of river restoration. I was also applied in development of the National river restoration program, for predicting the impact of proposed restoration measure on the state of hydromorphology.
The amount of sediments transported by a river is difficult to estimate, while this parameter could influence channel geometry. It is possible to derive the bedload transport rate per unit width of ...the river channel by measuring the migration distance of bedform profiles over time and thickness of bedload layer in motion. Other possible methods include instrumental measurements using bedload traps and empirical formulas. It is possible to use remote-sensing techniques to measure the dynamics of bedform movements and geometries. Landsat images and aerial photographs have been used for this. A new source of remote-sensing information is radar satellite images. Sentinel-1 images have a temporal resolution of 2–3 days and spatial resolution of 25 m at middle latitudes, which make them usable on large rivers. The research area is the 814–820 km reach of the Lower Vistula River, where seven alternate sandbars were selected. The bank lines of the sandbars were delineated on Sentinel-1 images sensed during two low-flow periods of 4 August–26 September 2018 and 1 July–31 August 2019, when discharges at low flow were similar. From water stage observations at gauges, water elevations were assigned to every bank line of the alternate sandbars. The following morphometric parameters were calculated: alternate sandbar centers, volumes and longitudinal profile. Average daily movement of the sandbars in the period 4 August 2018–1 July 2019 was calculated as 0.97 m·day−1. A similar alternate sandbar movement velocity was obtained from a study of Sentinel-2 optical satellite images and hydro-acoustic measurements on the Lower Vistula River. Having depth of bedload in motion and alternate sandbar shift velocities, it was possible to calculate the rate of bedload transport according to the Exner approach formula. Rate of bedload transport was estimated as qb = 0.027 kg·s−1·m−1. This study shows a novel use of Sentinel-1 images to study the 3D geometry and movement rate of sandbars.
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•Land use changes could more affecting on water retention than climate changes.•The negative influence of climate change can be mitigated by landscape management.•Landscape hydric ...potential help to adapt to changes in land use and climate.•Machine learning help to predict future effects of land use/land cover.
Are we losing water mostly due to climate change? This study delves into that question. The main innovation of this research lies in developing a methodology that forecasts future shifts in water resources through the use of nondimensional indicators, such as Landscape Hydric Potential (LHP), caused by climate change scenarios, land use and land cover (LULC) projections, and a combination of both factors. The LHP method draws upon a range of indicators that shape the geosphere at the catchment scale, namely: hydrogeological conditions, soil conditions, climatic conditions, geomorphological conditions, and LULC. The analysis was carried out for 33 catchments located in the Upper Vistula River Basin in East-Central Europe. The study was conducted in the following stages. First, LHP values were calculated for the present conditions. Subsequently, an analysis of anticipated changes in LULC and in climate were conducted for the near and far future. Lastly, simulations were performed to project how LHP might evolve, considering potential changes in climate and LULC over time. The results have shown that under current climatic conditions, mountainous catchments are characterized by higher LHP values than catchments located in highlands or plains. Agricultural areas are projected to experience the largest changes in LULC. Climatic water balance indicate minimal changes, irrespective of time horizon. Our studies conclude that changes in predicted LULC could have a more significant impact on LHP values than the projected climate change.
The prediction and calculation of the volume of gravel and/or sand transported down streams and rivers—called bed-load transport is one of the most difficult things for river engineers and designers ...because, in addition to field measurements, personnel involved in such activities need to be highly experienced. Bed-load transport treated by many engineers marginally or omitted and often receives only minor consideration from engineers or may be entirely disregarded simply because they do not know how to address the issue—in many cases, this is a fundamental problem in river management tasks such as: flood protection works; river bank protection works against erosion; building bridges and culverts; building water reservoirs and dams; checking dams and any other hydraulic structures. Thus, to share our experience in our paper, bed-load transport was calculated in two river/stream mountain catchments, which are different in terms of the characteristics of the catchment area and the level of river engineering works performed along the stream channel—both are tributaries of the Dunajec River and have similar Carpathian flysh geology. The studies were performed in the Mlyne stream and in the Lososina River in Polish Carpathians. Mlynne is one of the streams in the Gorce Mountains—it is prone to flash flooding events and has caused many problems with floods in the past. It flows partially in the natural river channel and partially in a trained river channel lined with concrete revetments. The stream bed load is accumulated in the reservoir upstream of the check dam. The Lososina River is one of the Polish Carpathian mountainous streams which crosses the south of the Beskid Wyspowy Mountains. It mostly has a gravel bed and it is flashy and experiences frequent flooding spring. At the mouth of the Lososina River, there is one of the largest Polish Carpathian artificial lakes—the Czchow lake. The Lososina mostly transports gravel as the bed load to the Czchow water reservoir where the sediment is deposited. In the early seventies, the Lososina was partly canalised, especially in places where passes inhabited areas. The paper compares the situation of bed-load transport in the Lososina River before and after engineering training works showing how much sediment is transported downstream along the river channel to the Czchow artificial lake. Also compared is the Mlynne bed load transport upstream and downstream from the check dam showing how much sediment might be transported and deposited in the reservoir upstream from the check dam and when one could expect this reservoir to be clogged.
An important aspect in the restoration of longitudinal connectivity in rivers and streams is the implementation of fish migration systems at the upstream of the functional hydraulic structures ...(weirs, drop structures or river sills). The diversity of these existing structures as well as the different locations of these weirs within the river, watershed and riparian zone challenge the design engineers to find new holistic solutions for fish migration systems. The Azuga River study area requires a new synergistic fish migration design system. Being a mountain area, rapid increase in water level is quite frequent, especially after heavy or prolonged rainfalls and during spring snow melt. Therefore, it is necessary to design a specific system for fish migration to meet this locations requirements. Due to the characteristics in this location of the Azuga river, the classic fish migration systems would not be functional. The indigenous/mountain trout is considered as the target species in this paper. Although this is a good swimming species, the use of classical systems could, due to exhaustion, prevent and/or reduce the movement of fish upstream of the two weirs (also known as river sills). This new, comprehensive solution, presented in this paper includes: (i) the restoration and stabilization works of the right bank in the weir study area by using biotechnical measures and (ii) the upstream migration system itself - for supporting the migration of fish on the Azuga River.
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