The assessment and mapping of riverine flood hazards and risks is recognized by many countries as an important tool for characterizing floods and developing flood management plans. Often, however, ...these management plans give attention primarily to open-water floods, with ice-jam floods being mostly an afterthought once these plans have been drafted. In some Nordic regions, ice-jam floods can be more severe than open-water floods, with floodwater levels of ice-jam floods often exceeding levels of open-water floods for the same return periods. Hence, it is imperative that flooding due to river ice processes be considered in flood management plans. This also pertains to European member states who are required to submit renewed flood management plans every six years to the European governance authorities. On 19 and 20 October 2022, a workshop entitled “Assessing and mitigating ice-jam flood hazard and risk” was hosted in Poznań, Poland to explore the necessity of incorporating ice-jam flood hazard and risk assessments in the European Union’s Flood Directive. The presentations given at the workshop provided a good overview of flood risk assessments in Europe and how they may change due to the climate in the future. Perspectives from Norway, Sweden, Finland, Germany, and Poland were presented. Mitigation measures, particularly the artificial breakage of river ice covers and ice-jam flood forecasting, were shared. Advances in ice processes were also presented at the workshop, including state-of-the-art developments in tracking ice-floe velocities using particle tracking velocimetry, characterizing hanging dam ice, designing new ice-control structures, detecting, and monitoring river ice covers using composite imagery from both radar and optical satellite sensors, and calculating ice-jam flood hazards using a stochastic modelling approach.
Abstract
Environmental flows have primarily a practical purpose, being an important part of water management. Despite the widespread use of environmental flows, current studies rarely describe ...practical insights of the methods or consider environmental flows based on ecological traits, especially regarding macroinvertebrates. In addition to hydraulic parameters, the ecological traits may also indicate processes that drive the distribution of organisms. Nevertheless, so far the habitat suitability criteria for functional feeding groups, the most commonly used ecological trait for macroinvertebrates, have not been described. In this study, we performed a detailed analysis of habitat suitability curves for the macroinvertebrate community and for FFGs. The criteria were determined based on data collected during two field campaigns (2018 and 2019) from the Flinta River, a lowland, dynamic, sandy stream located in western Poland. The method of habitat preference curves (HPCs) for flow velocities, depths and substrate was adopted. Before determining the final habitat suitability criteria, for all considered groups the habitat preference curves and habitat utilization curves were determined separately for the data collected in 2018 and 2019. The results showed that this step was key in developing the final habitat suitability criteria. Additionally, considering FFGs provided insight into the mechanisms that drove the distribution of organisms and resultant suitability.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The purpose of the present research was to analyze the available data on river restoration projects in Europe. As the framework of our study, we conducted a structured international survey. We asked ...selected entities and experts from among those responsible for river restoration in European countries about the details and costs of European Union river restoration projects. We examined 119 river restoration projects that were implemented in Europe between 1989 and 2016; during the collection of data, some of the projects were still ongoing. Based upon the collected data we observed that the number of river restoration projects has been increasing since 1989, which expresses society’s growing interest in improving the quality of aquatic environments. We revealed that 56% of these European river restoration projects have been implemented by dedicated entities and stakeholders, not as part of any structured, larger-scale river restoration policy. This indicates that most European countries do not have integrated plans for river restoration. Our analysis showed that 52% of the projects analyzed have been designed and implemented without the participation of local stakeholders. It also showed that the budgets for river restoration projects did not differ significantly across various time horizons from 1989 to 2016. In our study, the average cost of restoring 1 ha of an European river was 310,000 euros (EUR). Considering these projects’ permanent assets and including their amortization, we calculated the average unit price of a river restoration’s value in terms of ecosystem meta-service to be 7757 EUR·ha−1·year−1.
One of the most commonly used methods of environmental flows assessment is the approach based on Habitat Suitability Modeling (HSM) and habitat preferences curves (HPCs). Relationships between ...organisms and physical parameters describing the habitat remain strongly nonlinear and vary depending on several factors. The most common comparisons concern analyses between natural and regulated rivers, where the degree of river channel alterations is undefined and usually refers to all forms of hydromorphological degradation. Additionally, spatial scale and computational range of such a research mostly focus on longer river reaches and statistical analysis of HPC transferability, without detailed estimation of environmental flows values. The main aim of our research was assessment and comparison of environmental flows’ values for macroinvertebrates at two reaches of one river with different degrees of hydromorphological alteration. Two research hypotheses were verified: 1) morphological conditions impact on values of environmental flows and weighted usable area; 2) the mean value of environmental flows at the regulated river reach is higher compared to the natural reach. In order to put the obtained values of environmental flows into a broader context, the analyses of hydrological data and calculation of hydrology-based environmental flows were performed. Additionally, before determination of environmental flows, the transferability of habitat suitability criteria between reaches was verified. The obtained results confirmed research hypotheses, revealing strong dependence of environmental flows values to morphological conditions. Additionally, for both studied sections the lower limits of environmental flows were greater than hydrology-based values.
The aim of this study was to perform a simulation of sediment transport for the section of the river Ner, while also utilizing GIS tools. Using the ArcGIS numerical model of channel and stream ...valleys were developed, and motion simulations and sediment transport set for 5 ten-year periods were performed in HEC-RAS. Updated geometries after the simulations were created using the tools of RAS Mapper. ArcGIS was used again for analysing the results. It was used to generate ordinates of bottom in the initial state and final. The difference between them illustrated the magnitude of erosion and accumulation. The process of erosion occurred in 13 sections of the analysed model (the standard differential ordinates negative), while the accumulation in 53 sections. The maximum value of shallowing bottom was 1.24 m (cross-section at km 18 + 868), while the largest deepening occurred at km 8 + 654 (– 0.76 m). All values, using ArcGIS, were marked on othophotomap.
Despite many years of experience in the river restoration field, which has become one of the most promising areas of water resources management, significant challenges and problems remain. These ...include the scope and scale of restoration measures, developing the reference model, assessment of restoration success, and the engagement of local stakeholders. Progress in addressing these challenges to river restoration could be achieved by changes in current approaches through the appreciation and integration of local communities and their local ecological knowledge (LEK). The results of discussion on ecological restoration indicate that ecological knowledge, which combines the interests of local communities and the environment, could be used in restoration projects. However, in the case of river restoration, this type of knowledge is systematically overlooked. In our paper, we discuss common river restoration problems and supportive elements that may be found in LEK. We conclude that the local stakeholders’ involvement and strong establishment of their position in the river restoration processes should be reconsidered. We believe that the application of LEK has large potential for improving water resources management and restoration of aquatic ecosystems and remains a key factor in a successful future of river restoration.
The purpose of the paper is to test forecasting of the sediment transport process, taking into account two main uncertainties involved in sediment transport modeling. These are: the lack of knowledge ...regarding future flows, and the uncertainty with respect to which sediment transport formula should be chosen for simulations. The river reach chosen for study is the outlet part of the Ner River, located in the central part of Poland. The main characteristic of the river is the presence of an intensive morphodynamic process, increasing flooding frequency. The approach proposed here is based on simulations with a sediment-routing model and assessment of the hydraulic condition changes on the basis of hydrodynamic calculations for the chosen characteristic flows. The data used include Digital Terrain Models (DTMs), cross-section measurements, and hydrological observations from the Dabie gauge station. The sediment and hydrodynamic calculations are performed using program HEC-RAS 5.0. Twenty inflow scenarios are of a 10-year duration and are composed on the basis of historical data. Meyer-Peter and Müller and Engelund-Hansen formulae are applied for the calculation of sediment transport intensity. The methodology presented here seems to be a good tool for the prediction of long-term impacts on water surface profiles caused by sediment deposition and erosion.
It is becoming extremely challenging to protect the structural and functional integrity of freshwater ecosystems, as many ecological systems face pressures from climate change, population growth and ...other environmental impacts. However, existing approaches of assessing impacts of external stressors to habitat conditions often neglect the long‐term hydrological changes. This study aimed to develop an integrated modelling framework to assess impacts of different stressors on reach‐scale habitat conditions for benthic macroinvertebrates in a temperate lowland river in central Poland. We coupled hydrological (SWAT+), hydraulic (HEC‐RAS 1D and SRH‐2D) and habitat (CASiMiR) models to predict the response of habitat suitability for the functional group of filter feeders to changes in the catchment for a 135‐m section of the Jeziorka river. Setting up and calibrating individual models required extensive field data collection (e.g., bathymetry field surveys, gauging water levels, discharge and flow velocity measurements and biological sampling). The performance of individual models in simulating discharge, water levels and depth/flow velocity was assessed as satisfactory according to literature. The modelling chain was then applied to compare the effects of three flow scenarios (average, low and high flows). The results showed an overall high value of hydraulic habitat suitability index for filter feeders, with moderately and severely lower values for low and high flow scenario, respectively. The implemented modelling framework performed well could be applied to examine the impacts of climate change and other anthropogenic stressors on reach‐scale habitat conditions. Its practical implementation could be beneficial towards sustainable water resources and environmental flow regime development.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The possibility of effective control of selected dams in the Noteć Bystra river is analyzed. Such a control is expected to permit inundation of selected arable areas, e.g., peat grasslands, to avoid ...flooding of the city of Czarnków and the terrains located downstream. The chosen case study is the reach of the Noteć River between the dams Pianowka–Mikolajewo–Rosko. The analysis was made on the basis of simulations of the flow and regulation of dams in flood conditions. The flow peaks of hypothetical flood waves were designed according to the directions of the ISOK project (Informatyczny System Osłony Kraju przed nadzwyczajnymi zagrożeniami—IT System of the Country’s Protection Against Extreme Hazards) as the maximum flows over 10-years (p = 10%), 100-years (p = 1%), and 500-years (p = 0.2%). The obtained results are presented as longitudinal profiles of the water surface, maps of inundated areas and maps of inundated soils. The main conclusion is that the robust control of dams reduces the peak of flow during flood wave propagation and forces inundation of the a priori selected areas. It helps to decrease the spatial range of the flood hazard and significantly reduces risk related to floods.
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