Flash flood simulations in a steep catchment using Telemac2D - hydrodynamic rainfall-runoff model

Hydrodynamic

Perspectives on the environmental implications of sustainable hydro-power: comparing countries, problems and approaches

Perspectives on the Environmental Implications of Sustainable Hydropower gathers scientific papers from three of the worlds most important hydropower producers to discuss aspects of sustainable hydropower and the means by which it can be studied and achieved. The papers examine the application and use of new technologies and protocols for studying hydropower, adaptive management and the implications and use of long-term data sets for minimizing hydropower impacts on fish populations. The papers include a cross section of biological and hydrological experts. The implicit among country comparisons highlight a number of common hydropower themes, particularly the need to expand from single species studies to include broader consideration of the ecosystem, the importance of maintaining habitat, trait and species diversity and the need for consistently collected long-term data sets. Hydropower Sustainability Long-term studies Brazil Canada NorwaypublishedVersio

An acoustic sensor transmitter for in situ assessment of water quality and fish behaviour during chemical treatment of a parasite-infected river system : tag design and practical use

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Comparison of two hydrodynamic models for their rain-on-grid technique to simulate flash floods in steep catchment

In this study, two hydrodynamic models, TELEMAC-2D and HEC-RAS 2D, were compared for their Rain-on-Grid (RoG) technique with a particular focus on runoff generation processes in a small and steep catchment. Curve number (CN) method was applied in both the models to simulate two single storm events up to 20 h of duration, whereas the Green-Ampt Redistribution (GAR) method was additionally applied in HEC-RAS 2D for a multi-peak flood event with sustained flow between the peaks. CN and GAR methods were compared for this flood event, and a sensitivity analysis of the GAR parameters was also done. Moreover, the two models were compared for their calibration process, computational time, mesh size and shape, and model availability, in general, as well as the results including inundated areas, water depth, and velocity. The results indicate that both the models are capable of reproducing short duration single storm floods. NSE and R2 for both models ranged from 0.70 to 0.90 and from 0.93 to 0.95. However, the models struggled to reproduce the long- duration multi-peak flood event. The sensitivity analysis showed that the results are not very sensitive to the two GAR parameters which are responsible to influence the flow of the second peak in the flood event. Neither the CN nor the GAR infiltration method successfully replicated such events because the hydraulic models permanently lose infiltrated water from the domain. The returned sub-surface flow significantly contributes to river flow during these flood events; however, none of the model incorporates a return flow algorithm

Towards improving the hydrologic design of permeable pavements

The common approach to the hydrologic design of permeable pavements (PPs) uses synthetic rainfall events. This study assessed the validity of the design approach using synthetic rainfall events for undrained PP. Synthetic rainfall events (25-year return period) were used to design undrained pavements for five Norwegian cities. The effectiveness of these pavements was tested using long-term simulation (12–30 years) with high temporal resolution (1 min). The Storm Water Management Model (SWMM) was used to generate time series of surface runoff for PPs and flow duration curves were applied to analyse the hydrological performances. Designing PP using synthetic rainfall events was found to underestimate the storage layer depth of the permeable pavements leading to the frequent occurrence of surface runoff, which is considered a failure of the hydrologic design of undrained pavements. Long-term simulation of surface runoff was found to provide valuable information for the hydrologic design of PP and can be used as a basis for the PP hydrologic design. In the future, it is recommended to use long-term precipitation data generated from climate change models to incorporate the effect of climate change in the design of PP.publishedVersio

Application of HYPE in Norway

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Key hydraulic drivers and patterns of fine sediment accumulation in gravel streambeds: A conceptual framework illustrated with a case study from the Kiewa River, Australia

Fine sediment processes in gravel beds may have significant impacts to overall river ecosystem function. In addition to gravitational deposition, horizontal intragravel transport has been recognized to influence fine sediment accumulation. However, the specific hydraulic mechanisms and origin of fine sediment movement are not clearly identified. The purpose of this study was to investigate key hydraulic drivers and patterns of fine sediment accumulation. Using a conceptual framework to set the scene, we implemented an experimental setup in a gravel lateral bar subject to irregular flow fluctuations in the Kiewa River (Australia). We installed nine sets of sediment collector pairs and piezometers into the gravel. Each pair included one horizontally and one horizontally-vertically perforated collector. Mid-range, rather than peak flows, covering the site in water drove fine sediment deposited in the collectors. We estimated horizontal contribution to final deposition as 59%. Such contribution resulted from shear stresses > 3 N m− 2 promoting streamwise near-bed turbulence at the water-sediment interface during flooded conditions. Despite high subsurface hydraulic gradients, intragravel transport in the lower sediment layers via Darcy flow did not show any influence to fine sediment deposition. Our findings contribute to an improved understanding of fine sediment accumulation processes, key for overall river ecosystem functioning, particularly in regulated rivers

Analysis of environmental impacts of a pump-storage system between two Norwegian reservoirs considering climate scenarios

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Evaluating the stormwater management model for hydrological simulation of infiltration swales in cold climates

The Stormwater Management Model (SWMM) is a widely used tool for assessing the hydrological performance of infiltration swales. However, validating the accuracy of SWMM simulation against observed data has been challenging, primarily because well-functioning infiltration swales rarely produce surface runoff, especially over short monitoring periods. This study addresses this challenge by using measured subsurface water storage levels for calibration and validation. The study evaluated three SWMM modules, namely, the snowpack, aquifer, and low-impact development (LID) modules, to simulate subsurface water storage levels of an infiltration swale located in a cold climate region during snow and snow-free periods. Global sensitivity analysis was used to identify influential parameters within these modules. The findings revealed that only a few parameters significantly influenced model outputs. Moreover, the aquifer module outperformed the LID module in simulating subsurface water storage due to limitations in setting the initial saturation of the LID module. Furthermore, simulation accuracy was better during snow-free periods due to challenges in simulating snow dynamics during snow periods with the snowpack module. The calibrated models offer valuable insights into the long-term hydrological performance of infiltration swales, enabling practitioners to identify events that trigger flooding in these systems.publishedVersio