Assessment of Sedimentation in Barak River Reach Using HEC-RAS

In order to analysis the Heavy metals in the bottom mud at beng river, we put the river reach between the bridge of beng river beside the er’huang road and the bridge beside the yin’meng road as the main research object, survey 14 transects of bottom mud from three indications (Hg,Pb,Cr) of the river and build a relate standards about the pollution of bottom mud depend on the domestic standards, in this paper, we use the potential ecological risk index method which was putted forward by Swedish scientists Hakanson as the criterion of the pollution about heavy metals in the mud. The results show that: at the rive reach mentioned above, we found there are very high heavy metals content in the bottom mud.

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Modeling shelter abundance for juvenile Atlantic salmon in a residual flow reach of a hydro power plant using SSIIM 2

10.5194/egusphere-egu21-13319 ◽

2021 ◽

Author(s):

Spyros Pritsis ◽

Nils Ruther ◽

Kordula Schwarzwälder ◽

Anastasios Stamou

Keyword(s):

Grain Size ◽

Atlantic Salmon ◽

Size Distribution ◽

Grain Size Distribution ◽

Sediment Supply ◽

Substrate Composition ◽

Juvenile Atlantic Salmon ◽

River Reach ◽

Bed Changes ◽

Shelter Availability

Nowadays, the aquatic biodiversity is highly under pressure due to anthropogenic changes of the rivers such hydraulic structures changing the diversity of flow and aquatic fauna as well as sediment continuity. This can have severe consequences on the fish population in the river reach. Fish are strongly depending on a certain substrate composition throughout all their life stages. Juveniles for example are depending on a certain availability of shelter in the substrate in order to survive this stage.Therefore, we investigate the effects of changes in the sediment composition at a hydropower plant in Switzerland on the availability of potential shelter for juvenile fish. By utilizing the observed correlation between parameters describing the fine tail of a riverbed&#8217;s grain size distribution and shelter abundance for juvenile Atlantic salmon, we predict the available shelter in a river reach by using a 3D hydrodynamic numerical model directly coupled to a morphodynamic model. The initial substrate composition was assumed to be spatially uniform, its parameters based on a grain size distribution curve derived from collected sediment samples.This model can now be used for habitat improvement scenario modeling. Based on the assumption that a specific mixture of sediment coming from upstream travelling through the river reach will positively influence the potential shelter availability, different scenarios can be investigated. The baseline for comparison was the simulation of the bed changes without any sediment supply from upstream. The baseline discharge was set to 100 m3 /s and was applied for 24 hours. The resulting bed changes create a map of the potential shelter availability of this grain size mixture. Then, two scenarios with sediment inflow from the upstream boundary were simulated. One coarse and one fine mixture of sediment were chosen as inputs, with the goal of investigating their impact on shelter abundance. The former designed to have a positive effect while the latter expected to reduce interstitial voids in the substrate and have a negative effect on available shelter.The investigation is conducted as part of the EU Horizon 2020 funded project FIThydro (funded under 727830)

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Flume experiments on vegetated alternate bars

E3S Web of Conferences ◽

10.1051/e3sconf/20184002034 ◽

2018 ◽

Vol 40 ◽

pp. 02034 ◽

Cited By ~ 1

Author(s):

Giulio Calvani ◽

Simona Francalanci ◽

Luca Solari

Keyword(s):

Hydrological Regime ◽

Spatial Arrangement ◽

Flume Experiments ◽

Rigid Vegetation ◽

Hydraulic Conditions ◽

Laboratory Flume ◽

Alternate Bars ◽

River Reach ◽

Bed Slope ◽

And Migration

The planform morphology of a river reach is the result of the combined actions of sediment motion (erosion, transport and deposition), hydrological regime, development and growth of vegetation. However, the interactions among these processes are still poorly understood and rarely investigated in laboratory flume experiments. In these experiments and also in numerical modelling, vegetation is usually represented by rigid cylinders, although it is widely recognized that this schematization cannot reproduce the effects of root stabilization and binding on riverbed sediment. In this work, we focus on the effects of added vegetation on morphological dynamics of alternate bars in a straight channel by means of flume experiments. We performed laboratory experiments reproducing hydraulic conditions that are typical of gravel bed rivers, in terms of water depth, bed slope and bed load; these conditions led to the formation of freely migrating alternate bars. We then employed rigid vegetation that was deployed on the reproduced alternate bars according to field observations. Various vegetation scenarios, in terms of density and spatial arrangement, were deployed in the flume experiments such to mimic different maintenance strategies. Results show the effects of rigid vegetation on the alternate bar configuration on the overall topographic pattern, the main alternate bar characteristics (such as amplitude and wavelength) and migration rate.

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The effect of the pool and riffle on dissolved, non-conservative mass transport in rivers

Water Quality Research Journal ◽

10.2166/wqrjc.2013.051 ◽

2013 ◽

Vol 48 (3) ◽

pp. 232-242

Author(s):

Ian H. Halket ◽

Peter F. Rasmussen ◽

John C. Doering

Keyword(s):

Transport Model ◽

Low Flow ◽

Transport Models ◽

Cross Sectional ◽

Lower Velocity ◽

Regulatory Limits ◽

Uniform Channel ◽

River Reach ◽

Model Equations ◽

Sectional Shape

One-dimensional substance transport models assume that the river reach modelled has a uniform cross-sectional shape which manifests as a constant average velocity in the model equations. Rarely do rivers meet this criterion. Their channels are seldom uniform in shape but rather alternate in a quasi-periodic manner between pool and riffle sections. This bedform sequencing imparts a corresponding variation in the average cross-sectional velocity which is not accounted for in constant velocity transport models. The literature points out that the pool and riffle planform may be the reason for the sometimes poor predictions obtained from these models. This paper presents a new variable velocity transport model and confirms that the fluctuation in average cross-sectional velocity caused by the pool and riffle planform does have a marked effect on transport in rivers. The pool and riffle planform promotes an enhanced decay of a substance when a first-order biochemical reaction is simulated with the new transport equation. Investigation of the analytical solution shows that the enhanced decay is the result of the overall lower velocity experienced in a pool and riffle channel as opposed to a uniform channel. This difference in transport velocity between a pool and riffle channel and a uniform channel becomes more pronounced as flow declines a critical finding for total maximum daily load calculations because these regulatory limits are usually determined for low flow levels by models that do not account for this phenomenon.

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Daily and seasonal variability of CO2 saturation and evasion in a free flowing and in a dammed river reach

Journal of Limnology ◽

10.4081/jlimnol.2014.947 ◽

2014 ◽

Vol 73 (3) ◽

Cited By ~ 4

Author(s):

Monica Pinardi ◽

Marisa Rossetto ◽

Pierluigi Viaroli ◽

Marco Bartoli

Keyword(s):

Seasonal Variability ◽

River Reach ◽

Dammed River

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