Modelling hydrodynamics and ice formation in a pump-storage system between two Norwegian reservoirs

publishedVersio

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

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Multi-criteria decision analysis in Bayesian networks-Diagnosing ecosystem service trade-offs in a hydropower regulated river

The paper demonstrates the use of Bayesian networks in multicriteria decision analysis (MCDA) of environmental design alternatives for environmental flows (eflows) and physical habitat remediation measures in the Mandalselva River in Norway. We demonstrate how MCDA using multi-attribute value functions can be implemented in a Bayesian network with decision and utility nodes. An object-oriented Bayesian network is used to integrate impacts computed in quantitative sub-models of hydropower revenues and Atlantic salmon smolt production and qualitative judgement models of mesohabitat fishability and riverscape aesthetics. We show how conditional probability tables are useful for modelling uncertainty in value scaling functions, and variance in criteria weights due to different stakeholder preferences. While the paper demonstrates the technical feasibility of MCDA in a BN, we also discuss the challenge

Modeling the trade-off between production of Atlantic Salmon (Salmo salar) and power at Laudal Hydropower plant.

A modelling study on the trade-offs between the production of Atlantic salmon (Salmo salar) and the production of power at Laudal hydropower plant was conducted. The study examined the use of physical mitigation measures versus - and in addition to - changes in release of water. The study objective is an optimization of the environmental design through and downstream of the Bjelland and Laudal Hydropower plants in the Mandalselva River in Southern Norway, through demonstration and evaluation of a proposed methodology, to be used in other projects/rivers. The methodology is a tool for a) prediction of the potential trade-offs between smolt production and power generation b) evaluation of cost-effectiveness in smolt production and loss in power production (spill of water). At the end, as an additional point the data at Laudal will be compared with the results in the upstream bypass section at Bjelland reach, in order to see the effects in different stretches if the same mitigation measures are implemented

Performance of A Two-Dimensional Hydraulic Model for the Evaluation of Stranding Areas and Characterization of Rapid Fluctuations in Hydropeaking Rivers

Extreme, short-duration fluctuations caused by hydropeaking occurs when hydropower is regulated to cover demand peaks in the electricity market. Such rapid dewatering processes may have a high impact on the downstream biological conditions, particularly related to stranding of fish and other species. The present work analyzes these fluctuations using a two-dimensional unsteady hydraulic modelling approach for quantification of two important hydro-morphological factors on fish stranding risk: the variation in wetted area and the dewatering ramping rate. This approach was applied on the two-kilometer-long reach of Storåne downstream of the Hol 1 power plant, where topo bathymetric LiDAR (Light Detection and Ranging) data was available providing a high-resolution digital elevation model. Based on this model, hydraulic conditions could be simulated in high detail allowing for an accurate assessment of the hydro morphological factors. Results show the dried area distribution at different flows and dewatering ramping rates. The attenuation of the water level fluctuation due to the damping effect along the river reach controls the dewatering rate. We recommend an alternative scenario operation which can reduce the impact of the peaking operation and estimate the operational mitigation cost. We find that the modelling based on the fine resolution grid provides new opportunities in assessing effects of hydropower regulations on the ecosystem

Cost-effective environmental mitigation measures i hydropower rivers

727830publishedVersio

Hydropower‐driven thermal changes, biological responses and mitigating measures in northern river systems

Water temperatures control life histories and diversity of aquatic species. Hydropowerregulation, particularly in high head systems, alters natural water temperature regimes,which may have profound and long-term impacts on aquatic environments. Tempera-tures in by-pass sections and reaches affected by residual/environmental minimum flowsfluctuate more than in natural flow regimes, driven more by influence of air tempera-tures. Reaches downstream of power plant outlets tend to become warmer in winter andcolder in summer, driven by stratification behind the reservoir dam. In hydro-peaked sys-tems high-low temperature effects may thus be aggravated. We review alterations ofhydropower to natural thermal regimes, impacts on key organisms in terms of survival,development and behavioral thresholds, and potential mitigation measures, with focus onAtlantic salmon and brown trout in high northern latitude stream systems. Previous syn-theses have focused mainly on flow changes and ecological impacts. Temperature effectsmay not always be correlated with flow changes, although there are some unique chal-lenges with temperature changes in far northern latitudes, for example, related to theseasonal and colder climates. To help knowledge-based management and identify poten-tial knowledge gaps, we review how hydropower regulation may impact seasonal watertemperatures, what impacts changes to stream system temperature regimes may have tokey organisms, for example, Atlantic salmon and brown trout, and what adaptations andbehavioral variations they may exhibit to respond to changed temperature regimes, andfinally what good practices can be recommended for mitigating temperature impacts.This synthesis indicates that there are impacts to the fish and their supporting food webs,in particular related to growth and development, and the potential for negative impactsseems higher, and better studied, than positive impacts in northern river systems. Someof these impacts may be modified by directed hydropower regulation practices, but hereeffect studies and knowledge are limited.publishedVersio

Allocation of water consumption in multipurpose reservoirs

acceptedVersio