Rivers In Germany Research Articles

Addressing societal challenges through nature-based solutions: How can landscape planning and governance research contribute?

Nature-based solutions (NBS) in river landscapes, such as restoring floodplains, can not only decrease flood risks for downstream communities but also provide co-benefits in terms of habitat creation for numerous species and enhanced delivery of diverse ecosystem services. This paper aims to explore how landscape planning and governance research can contribute to the identification, design and implementation of NBS, using the example of water-related challenges in the landscape of the Lahn river in Germany. The objectives are (i) to introduce the NBS concept and to provide a concise definition for application in planning research, (ii) to explore how landscape planning and governance research might support a targeted use and implementation of NBS, and (iii) to propose an agenda for further research and practical experimentation. Our methods include a focused literature review and conceptual framework development. We define NBS as actions that alleviate a well-defined societal challenge (challenge-orientation), employ ecosystem processes of spatial, blue and green infrastructure networks (ecosystem processes utilization), and are embedded within viable governance or business models for implementation (practical viability). Our conceptual framework illustrates the functions of NBS in social-ecological landscape systems, and highlights the complementary contributions of landscape planning and governance research in developing and implementing NBS. Finally, a research and experimentation agenda is proposed, focusing on knowledge gaps in the effectiveness of NBS, useful approaches for informed co-design of NBS, and options for implementation. Insights from this paper can guide further studies and support testing of the NBS concept in practice.

Numerical modelling of stream–aquifer interaction: Quantifying the impact of transient streambed permeability and aquifer heterogeneity

AbstractStream–aquifer interaction plays a vital role in the water cycle, and a proper study of this interaction is needed for understanding groundwater recharge, contaminants migration, and for managing surface water and groundwater resources. A model‐based investigation of a field experiment in a riparian zone of the Schwarzbach river, a tributary of the Rhine River in Germany, was conducted to understand stream–aquifer interaction under alternative gaining and losing streamflow conditions. An equivalent streambed permeability, estimated by inverting aquifer responses to flood waves, shows that streambed permeability increased during infiltration of stream water to aquifer and decreased during exfiltration. Aquifer permeability realizations generated by multiple‐point geostatistics exhibit a high degree of heterogeneity and anisotropy. A coupled surface water groundwater flow model was developed incorporating the time‐varying streambed permeability and heterogeneous aquifer permeability realizations. The model was able to reproduce varying pressure heads at two observation wells near the stream over a period of 55 days. A Monte Carlo analysis was also carried out to simulate groundwater flow, its age distribution, and the release of a hypothetical wastewater plume into the aquifer from the stream. Results of this uncertainty analysis suggest (a) stream–aquifer exchange flux during the infiltration periods was constrained by aquifer permeability; (b) during exfiltration, this flux was constrained by the reduced streambed permeability; (c) the effect of temporally variable streambed permeability and aquifer heterogeneity were found important to improve the accurate capture of the uncertainty; and (d) probabilistic infiltration paths in the aquifer reveal that such pathways and the associated prediction of the extent of the contaminant plume are highly dependent on aquifer heterogeneity.

Distribution of Escherichia coli, coliphages and enteric viruses in water, epilithic biofilms and sediments of an urban river in Germany

Fecal contamination of surface water is commonly evaluated by quantification of bacterial or viral indicators such as Escherichia coli and coliphages, or by direct testing for pathogens such as enteric viruses. Retention of fecally derived organisms in biofilms and sediments is less frequently considered. In this study, we assessed the distribution of E. coli, somatic coliphages, and enteric viruses including human adenovirus (HAdV), enterovirus (EV), norovirus genogroup GII (NoV GII) and group A rotavirus (RoV) in an urban river environment in Germany. 24 samples each of water, epilithic biofilms and sediments were examined. E. coli and somatic coliphages were prevalent not only in the flowing water, but also in epilithic biofilms and sediments, where they were accumulated compared to the overlying water. During enhanced rainfall, E. coli and coliphage concentrations increased by approximately 2.5 and 1 log unit, respectively, in the flowing water, whereas concentrations did not change significantly in epilithic biofilms and sediments. The occurrence of human enteric viruses detected by qPCR was higher in water than in biofilms and sediments. 87.5% of all water samples were positive for HAdV. Enteric viruses found less frequently were EV, RoV and NoV GII in 20.8%, 16.7% and 8.3% of the water samples, respectively. In epilithic biofilms and sediments, HAdV was found in 54.2% and 50.0% of the samples, respectively, and EV was found in 4.2% of both biofilm and sediment samples. RoV and NoV GII were not detected in any of the biofilms and sediments. Overall, the prevalence of enteric viruses was in the order of HAdV > EV > RoV ≥ NoV GII. In conclusion, epilithic biofilms and sediments can be reservoirs for fecal indicators and enteric viruses and thus should be taken into consideration when assessing microbial pollution of surface water environments.

Evening Transition by a River Sampled Using a Remotely-Piloted Multicopter

Measurements made with instruments aboard a remotely-piloted multicopter flying across the Weser river in Germany provide information on the thermal structure of the boundary layer over the river and adjacent land, in this case in summer for late afternoon, the evening transition and early night on a clear calm day. The river has a characteristic width of 100 m. The stratification over the land and river are of opposite signs at the lower levels, except during part of the evening transition. The multicopter allows to qualitatively estimate the evolution of the thermal contrast between both surfaces, showing that the river banks experience very significant daytime cooling and nocturnal warming due to river-bank circulations, with the change of sign taking place well before sunset.

The study of the variability of biomass from plants of the Elodea genus from a river in Germany over a period of two hydrological years for investigating their suitability for biogas production

BackgroundAquatic plants are an important component of aquatic ecosystems. They are valuable for the oxygen and carbon dioxide household and generate habitats especially for small fish and other small organisms. However, problems for the maintenance of water bodies can result from mass occurrences of these plants. Invasive neophytes - such as members of the Elodea genus - are particularly problematic in this regard. Aquatic plants need to be harvested regularly to ensure that water bodies remain usable and to safeguard flood protection for flowing water bodies. Energy can be produced from the harvested material by anaerobic digestion in biogas plants. Therefore, it is beneficial to know the best time for harvesting in this context.MethodsTo identify the best time for harvesting, samples of the Elodea stock in the river Parthe in Leipzig-Schönefeld were taken each week over the course of the two hydrological years 2015 and 2016. The composition of these samples was analyzed in the laboratory. In the second hydrological year, three samples from surface areas of 1 m2 were also harvested once each month in order to determine the biomass yield per unit area.ResultsThe best harvesting time for energy production from Elodea biomass in Germany is in the summer months (June to September). During this period, the specific yield of 0.5–0.7 kg VS/m2 is relatively high and the Elodea biomass contains the highest fractions of volatile solids (80.1 ± 2.3%), high contents of plant nutrients (N 35.9 ± 4.0 g/kg TS; P 6.1 ± 1.4 g/kg TS; and K 47.7 ± 8.0 g/kg TS), and low concentrations of heavy metals (Cr ≤8.9 mg/kg TS, Cd ≤0.9 mg/kg TS, Cu ≤120 mg/kg TS, Ni ≤30 mg/kg TS, Pb ≤8.6 mg/kg TS, and Zn ≤439 mg/kg TS).ConclusionsEnergy production from Elodea biomass is feasible. This biomass also provides the nutrients and trace elements necessary for the digestion in the anaerobic process.

Ecosystem services in infrastructure planning – a case study of the projected deepening of the Lower Weser river in Germany

We consider how ecosystem services can be incorporated into water infrastructure planning by studying the projected deepening of the Lower Weser river channel in Germany. We recalculate the project's benefit–cost ratio by integrating the monetary value of changes in different ecosystem services, as follows: (1) the restoration costs of a mitigation measure for a loss in fresh water supply for agricultural production in the estuary region, (2) the costs of a loss in habitat services, transferring the willingness to pay from a contingent valuation study to the area assessed in the environmental impact assessment, and (3) the benefits of emissions savings induced by more efficient shipping, taking a marginal abatement cost approach. We find that including monetary values for ecosystem service changes leads to a substantial drop in the benefit–cost ratio. On this basis, we argue for a reform of the standard cost–benefit analysis to facilitate more complete welfare assessments.

Unified Hydrological Flow Routing for Variational Data Assimilation and Model Predictive Control

Hydrological flow routing covers a class of simple and computationally highly efficient techniques for steep river reaches without backwater effects. It is often applied as a routing component in semi-distributed and distributed hydrological models or as a stand-alone routing scheme in flow forecasting systems. If embedded into variational data assimilation (DA) or model predictive control (MPC), i.e. running the model in optimization mode, three main characteristics of the routing approach become essential: i) numerical robustness, ii) mass conservation and iii) the efficient computation of first-order sensitivities.We present a unified approach in which we reformulate various hydrological routing approaches as a cascade of non-linear reservoirs. This covers linear and nonlinear reservoir routing as well as Muskingum-type schemes. Whereas original variable-parameter versions of these schemes, e.g. Muskingum-Cunge, are not mass conservative, the reformulated version guarantees strict mass conservation. An iterative Newton-Raphson scheme integrates the implicit schematization of the reservoir equation in time. The first order sensitivities are derived by the implicit function theorem and the adjoint sensitivity equation at the computational costs of the time integration itself.The novel framework is applied to an academic test case and a routing network in the upper basin of Main River in Germany. Results show the performance of the routing scheme and verify the mass conservation properties of the approach. Furthermore, we give an outlook at the future use of the model within variational DA and MPC scenarios.

Extraction of geoid heights from shipborne GNSS measurements along the Weser River in northern Germany

Abstract In-land geoid models rely on several measuring techniques. The quality of those models is directly related to the spatial resolution of the measurement data. Occasionally, a local geoid model does not cover the coastal area at all and a local marine geoid simply does not exist. ShipborneGNSS measurementsmay provide away of overcoming this problem in coastal areas. However, several corrections to the raw measurements must be applied in order to account for systematic effects induced by ship dynamics and other static and dynamic impacts from tides, atmospheric pressure or wind stress. This paper presents the theoretical background for the method and the results of a case study in the estuary of the Weser River in Germany. A series of GNSS measurements were carried out aboard a ship and the approximate geoid height along the river was derived. For accuracy assessments of this method, the resultswere compared to the German Combined QuasiGeoid 2011 (GCG2011). The results are very promising and indicate the ability to extract geoid heights from shipborne GNSS measurements.

Viaduct over Ulla River in the Atlantic high speed railway line: A composite (steel–concrete) truss world record

With the commissioning of the Atlantic high speed railway line between Pontevedra and A Coruña, in the spring of 2015, the viaduct over the river Ulla has achieved the world record in the typology of high speed composite truss bridge, with three main spans of 225+240+225m. This exceeds the Nantenbach Bridge over Main River in Germany, which held the record since its conclusion in 1993 with a 208m span.This article describes in detail the design and the main features of the viaduct, the new system of quality control of the execution implemented with great success. A description is also presented on the complex and outstanding construction processes used for the execution of the deck of the bridge and the foundation of the piers located on the river, with the exceptional temporary works that have been fabricated “ex profeso” for the execution.

El viaducto del río Ulla en el Eje Atlántico de Alta Velocidad: una celosía mixta récord del mundo

With the commissioning of the Atlantic High Speed Railway Line between Pontevedra and A Coruña, in the spring of 2015, the viaduct over the river Ulla has achieved the world record in the typology of high speed composite truss bridge, with three main spans of 225+240+225m. This exceeds the Nantenbach Bridge over Main River in Germany, which held the record since its conclusion in 1993 with a 208m span.This article describes in detail the design and the main features of the viaduct, the new system of quality control of the execution implemented with great success. A description is also presented on the complex and outstanding construction processes used for the execution of the deck of the bridge and the foundation of the piers located on the river, with the exceptional temporary works that have been fabricated ex profeso for the execution.

Rare earth elements in the aragonitic shell of freshwater mussel Corbicula fluminea and the bioavailability of anthropogenic lanthanum, samarium and gadolinium in river water

High-technology metals — such as the rare earth elements (REE) — have become emerging contaminants in the hydrosphere, yet little is known about their bioavailability. The Rhine River and the Weser River in Germany are two prime examples of rivers that are subjected to anthropogenic REE input. While both rivers carry significant loads of anthropogenic Gd, originating from contrast agents used for magnetic resonance imaging, the Rhine River also carries large amounts of anthropogenic La and lately Sm which are discharged into the river from an industrial point source.Here, we assess the bioavailability of these anthropogenic microcontaminants in these rivers by analyzing the aragonitic shells of the freshwater bivalve Corbicula fluminea. Concentrations of purely geogenic REE in shells of comparable size cover a wide range of about one order of magnitude between different sampling sites. At a given sampling site, geogenic REE concentrations depend on shell size, i.e. mussel age.Although both rivers show large positive Gd anomalies in their dissolved loads, no anomalous enrichment of Gd relative to the geogenic REE can be observed in any of the analyzed shells. This indicates that the speciations of geogenic and anthropogenic Gd in the river water differ from each other and that the geogenic, but not the anthropogenic Gd is incorporated into the shells. In contrast, all shells sampled at sites downstream of the industrial point source of anthropogenic La and Sm in the Rhine River show positive La and Sm anomalies, revealing that these anthropogenic REE are bioavailable. Only little is known about the effects of long-term exposure to dissolved REE and their general ecotoxicity, but considering that anthropogenic Gd and even La have already been identified in German tap water and that anthropogenic La and Sm are bioavailable, this should be monitored and investigated further.

Mineralogy and mineral chemistry of detrital heavy minerals from the Rhine River in Germany as evidence to their provenance, sedimentary and depositional history: focus on platinum-group minerals and remarks on cassiterite, columbite-group minerals and uraninite

In the course of studying the gold-bearing heavy mineral spectrum of sediments from the upper Rhine River, a distinct suite of detrital grains comprising platinum-group minerals (PGM), cassiterite, columbite-group minerals and uraninite was identified and investigated using conventional and modern analytical methods. This study aimed to characterize the selected mineral groups mineralogically and geochemically in order to identify possible source areas and to reconstruct different aspects of the complex sedimentary history of the Rhine River sediments. The PGM assemblage is dominated by grains of Ru–Os–Ir alloys (~70 %), followed by Pt–Fe alloys, sperrylite and rare other PGM. Accordingly, this PGM assemblage represents highly mature, physically and chemically extremely resistant compounds which may have experienced and survived repeated reworking during their sedimentary history. Pt–Fe alloys and sperrylite may originate from various sources; however, the predominant Ru–Os–Ir alloy grains point to an origin from ophiolite sequences of unknown age (but likely pre-Alpine; Variscan or older). The exact locations of the primary sources and the complex, prolonged sedimentary history of the detrital PGM with possibly multiple intermittent storages remain unknown. Detrital cassiterite grains were dated by the U–Pb method using LA-ICP-MS. The age dates of cassiterite largely overlap with zircon age distributions by peaking distinctly at ca. 325 Ma (majority of ages), thereby implying a predominantly Variscan age of the cassiterite grains and possible derivation from mineralization in the Black Forest area. Columbite-group minerals are dominantly tapiolite originating from pegmatites. Rare uraninite grains attest that this mineral experienced rapid erosion, transport and deposition in a reducing environment.

Variable parameter McCarthy–Muskingum routing method considering lateral flow

Summary The fully mass conservative variable parameter McCarthy–Muskingum (VPMM) method recently proposed by Perumal and Price (2013) for routing floods in channels and rivers without considering lateral flow is extended herein for accounting uniformly distributed lateral flow contribution along the reach. The proposed procedure is applied for studying flood wave movement in a 24.2 km river stretch between Rottweil and Oberndorf gauging stations of Neckar River in Germany wherein significant lateral flow contribution by intermediate catchment rainfall prevails during flood wave movement. The geometrical elements of the cross-sectional information of the considered routing river stretch without considering lateral flow are estimated using the Robust Parameter Estimation (ROPE) algorithm that allows for arriving at the best performing set of bed width and side slope of a trapezoidal section. The performance of the VPMM method is evaluated using the Nash–Sutcliffe model efficiency criterion as the objective function to be maximized using the ROPE algorithm. The twenty-seven flood events in the calibration set are considered to identify the relationship between ‘total rainfall’ and ‘total losses’ as well as to optimize the geometric characteristics of the prismatic channel (width and slope of the trapezoidal section). Based on this analysis, a relationship between total rainfall and total loss of the intermediate catchment is obtained and then used to estimate the lateral flow in the reach. Assuming the lateral flow hydrograph is of the form of inflow hydrograph and using the total intervening catchment runoff estimated from the relationship, the uniformly distributed lateral flow rate q L at any instant of time is estimated for its use in the VPMM routing method. All the 27 flood events are simulated using this routing approach considering lateral flow along the reach. Many of these simulations are able to simulate the observed hydrographs very closely. The proposed approach of accounting lateral flow using the VPMM method is independently verified by routing flood hydrograph of 6 flood events which are not used in the total rainfall vs total loss relationship established for the intervening catchment of the studied river reach. Close reproduction of the outflow hydrographs of these independent events using the proposed VPMM method accounting for lateral flow demonstrate the practical utility of the method.

3D numerical simulation of free surface flows over hydraulic structures in natural channels and rivers

In this paper, a three-dimensional numerical model is developed, in which an Euler implicit method for the temporal discretization and the Finite Volume Method for the spatial discretization are applied to solve the Reynolds-averaged Navier–Stokes (RANS) equations for free surface flows over hydraulic structures in natural channels and rivers. At the free surface two different methods, the front-tracking and the front-capturing, are applied to calculate free surface profiles. The model has been validated against typical benchmarking experiments, and applied to a number of practical applications for natural rivers in Germany. Due to the limitation of the observation data in some application cases, in order to verify our numerical model, we besides have modified and applied the well-known open source CFD toolbox OpenFOAM to the same applications, then compared the results obtained from the OpenFOAM with our model results.

Age and growth of European eels (Anguilla anguilla) in the Elbe River system in Germany

Models to describe the stock dynamics of the endangered European eel, Anguilla anguilla, are needed on river system level to develop conservation management strategies. For these models, estimations of age and growth of local eel stocks are important prerequisites. To investigate the variation of these two parameters I collected 160 European silver eels grouped by 100mm size classes at capture from the lower part of the Elbe River in Germany during fall 2011. Length of collected eels ranged from 360mm to 957mm and age from 7 years to 23 years. Mean age and growth, estimated by otolith increments, were higher for females (14 years, growth 52mmyear−1) than for males (13 years, 35mmyear−1). Larger females were older and grew faster as compared to smaller females. Across all size classes at capture, the weighted mean age and annual length increment based on the percentage of eels per size class of the migrating silver eels were 13 years and 50mmyear−1, respectively. The parameters of the von Bertalanffy growth model L∞, k and t0 for silver eels are given, which can be used to model the dynamics of the eel stock of the Elbe River system.

Population ecology of endangered white-clawed crayfish (Austropotamobius pallipess. str.) in a small rhithral river in Germany

Sound knowledge on distribution and ecology of imperiled species is an essential prerequisite for effective conservation planning. Here, we report the distribution and autecological traits of a newly discovered population of critically-endangered white-clawed crayfish (Austropotamobius pallipes s. str.) in a small river in southwestern Germany. Using an established crayfish survey protocol, we detected white-clawed crayfish in a river stretch of 4.5 km, with an estimated abundance of 1.4 ± 0.2 indiv.·m-2 . The sex ratio was even and sexual maturity was attained at approximately 25 mm carapace length (CL ). Life-history traits, as assessed using Von Bertalanffy’s growth function, indicate a life history most similar to populations in France, with longevity, asymptotic size, and growth performance index being higher in males than in females (11 y, 46 mm CL , and 2.8 and 9 y, 41 mm CL , and 2.7, for males and females, respectively). Estimated fecundity ranged from 9 to 135 eggs·female-1 (mean: 90 ± 28). White-clawed crayfish were also found in lower reaches of small tributary streams, of which one also featured endangered stone crayfish (Austropotamobius torrentium ). A syntopic occurrence of both species was recorded for the first time within a short stretch. Implications for species conservation are discussed.

Does bias correction increase reliability of flood projections under climate change? A case study of large rivers in Germany

ABSTRACTThere is a large uncertainty associated with flood projections driven by different climate scenarios. The bias‐corrected regional climate scenarios are widely used to drive hydrological models in climate impact studies, but there are also doubts and questions about the application of bias correction (BC) methods. This study aims to investigate the performance and impacts of BCs on flood projections in Germany. The distribution mapping method was applied to correct the climate data from the regional climate models (RCMs) CCLM (Cosmo‐Climate Local Model) and REMO (REgional MOdel) developed in Germany. The results show that BC can effectively reduce bias in the simulated average annual discharge, but the uncertainty of simulated floods remains due to the imperfect correction of extreme precipitations. About 75% of the change directions in the 50‐year flood discharge remain the same before and after the BC was used. The relatively short control period of 40 years and the assumption of stationarity of the BC method are two important and problematic issues for flood projections. Hence, it is difficult to prove that BC can increase reliability of flood projections. The direct use of RCM outputs for the control and scenario periods may still be useful for flood impact studies. In addition, a bilateral analysis of RCM and hydrological model performance involving the meteorologists and hydrologists could be helpful for reducing the bias of the RCM outputs in the future.

Simplified hydraulic modelling in model predictive control of flood mitigation measures along rivers

Model predictive control (MPC) is an advanced technique for controlling water resources systems over short-term prediction horizons by optimizing control trajectories of hydraulic structures. Future system states are forecasted by an internal model that simulates the system response to a set of external disturbances and control inputs. This paper deals with the design and numerical implementation of dedicated simplified hydraulic models for representing flood routing processes in MPC. We present alternatives for the numerical implementation in simulation mode as well as first-order sensitivity mode and discuss the trade-off between model accuracy and computational performance in sequential and simultaneous MPC set-ups in application to two test cases: The first one is a fictitious estuary case with little potential for simplifying the full dynamic model. The second case is an application of MPC to the control of flood detention measures along the Rhine River in Germany. Both cases show the high potential ...

Modelling nitrogen retention in floodplains with different degrees of degradation for three large rivers in Germany

Floodplains perform a variety of ecosystem functions and services – more than many other ecosystems. One of these ecosystem services is the reduction in nitrogen (N) loads and a subsequent improvement to the water quality. Since diffuse and also point nitrogen sources continue to cause a variety of problems in rivers and floodplains, inundated floodplains could act as net sinks for N and are therefore of great importance throughout Germany and Europe. This study analyses the effects of riparian floodplains on N-retention on the landscape scale for three large river systems with different degrees of degradation. Two approaches, differing in terms of the complexity of their respective input data and methods, were applied under wet and dry conditions. Whereas the proxy-based approach considers proxy values for N-retention, the model-based approach accounts for event-driven dynamic input data such as the extent of the inundated floodplain and incoming loads. Comparing the results of the two approaches it can be observed that floodplains of the near-natural river can retain up to 4% of the river load under wet conditions. During such conditions N-retention in floodplains is similar to that of rivers. For the two other floodplains, the results of the two approaches were quite different, showing lower N-retention capacities. However, for these floodplains as well, both approaches are suitable for calculating measurable N-retention rates, which is an important result because it also suggests that even degraded floodplains still preserve this particular ecosystem function and therefore still contribute to improving the quality of river water.

An Approach for Real-time Levee Health Monitoring Using Signal Processing Methods

We developed a levee health monitoring system within the UrbanFlood project funded under the EU 7th Framework Programme. A novel real-time levee health assessment Artificial Intelligence system is developed using data-driven methods. The system is implemented in the UrbanFlood early warning system. We present the application of dedicated signal processing methods for detection of leakage through the water retaining dam and subsequent analysis of the measurements collected from one of the UrbanFlood pilot levees at the Rhine river in Germany.