2 Hydraulic Engineering for Nature - 2.1 River Water Bodies Flashcards

1
Q

Learning objectives:

A

 You understand morphological processes in rivers, and their ecological importance.
 You know relevant hydraulic structures, in particular for supporting fish migration.

Basics in hydraulic computation are subject of other lectures in civil and environmental engineering, e.g. hydromechanics

Basics in river ecology are treated in this module within the Fresh Water Ecology course (Dr. Bäthe). We connect engineering and biology!

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2
Q

River Water Bodies

A

Typical situation of rivers with intensively used flood plains in Central Europe. Even after restoration, there are levees on both sides of the river for flood protection of the surrounding area – but now, the river course is more heterogenous with higher variability of hydraulic conditions.

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3
Q

Morphological Zones (Longitudinal)

see image slide 4

A

 Spring region:
– temperature depends on groundwater, low amplitude
– low oxygen, low primary production
– often without fish

 Upper part (rhithral):
– temperature amplitude low
– high oxygen, high velocity/turbulence
– stones and sand

 Lower part (potamal):
– high amplitude of water temperature
– low oxygen, low velocity/turbulence
– sand and mud

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4
Q

River Course within the Flood Plain

See image slide 5

A

natural course of river

man-made layout of river

near-natural layout of river

natural course of river partially preserved as bayou

valuable biotopes

bay

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5
Q

Some Terms from Ecology:

Ecology

A

scientific discipline about the interrelationships between creatures with each other and with the environment

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6
Q

Some Terms from Ecology:

Biocenosis

A

community of different kinds of plants and animals within a biotope, which is based on interdependency and interference.

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7
Q

Some Terms from Ecology:

Biotope

A

living space of a biocenosis, which contains several habitats.

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8
Q

Some Terms from Ecology:

Habitat

A

living space of one species (animal or plant).

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9
Q

Some Terms from Ecology:

Ecosystem

A

functional unit from biocenosis and biotope, characterised through interdependency of matter, energy and information fluxes between organisms with each other and with their environment.

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10
Q

Environmental Factors:

  1. Abiotic (inanimate) factors
A

– climatic (temperature, precipitation, light),

– physical (flow velocity, depth of water, waves),

– chemical (pH, oxygen, conductivity, nutrients),

– orographic (elevation, land surface, exposition),

– anthropogenic (structures and infrastructure).

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11
Q

Environmental Factors:

  1. Biotic (animate) factors
A

– Influence of microorganisms, plants, animals and humans against and with each other

– Food chain: animals eat plants, animals eat other animals

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12
Q

Simplified scheme of matter cycles and energy

flow in a closed system

A

see image slide 7

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13
Q

Abundance and Diversity of Creatures:

Abundance

A

Number of organisms per area or spatial unit.

– Absolute abundance of individuals: number of individuals of one species within a habitat (population density)
– Absolute abundance of species: number of species within a habitat
– Relative abundance: number of individual words of one species related with the total number of individuals

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14
Q

Abundance and Diversity of Creatures:

Dominance

A

single species dominate according to the number

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15
Q

Abundance and Diversity of Creatures:

Diversity

A

diversity of species in a biocenosis under consideration of the number of species and relative abundance

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16
Q

Abundance and Diversity of Creatures:

Diversity index after Shannon-Weaver

A

See equation slide 8

17
Q

Ecological State According to EU-WFD:

Biological components

A

– Composition and abundance of aquatic flora,
– Composition and abundance of benthic invertebrates,
– Composition, abundance and age structure of fish

18
Q

Ecological State According to EU-WFD:

Physical and chemical components

A

– Temperature conditions, oxygen conditions, salt content, acidity, nutrient conditions
– Specific pollutants of high ecological relevance

19
Q

Ecological State According to EU-WFD:

Hydro-morphological components

A

– Water balance: runoff and runoff dynamics, connectivity between surface and groundwater bodies
– Ecological continuity
– Structure of rivers

20
Q

Parameters of River Structure (LAWA, 2000)

A

See table slide 10

21
Q

Riparian Buffer Zones

A

 Strips of grass, shrubs, and/or trees along the banks of rivers

 Provide a transition zone between water and human land use
– important habitats along the riparian zone (wildlife and aquatic)

 Filter polluted runoff (“Vegetative Filter Strips”)
– catch sediment from surface runoff
– trap pollutants that could otherwise wash into surface and groundwater: phosphorus and nitrogen from fertilizer and animal waste, up to 80 % of excess phosphorus can be captured
– buffer zone is a sink of nutrients (stored in the biomass of plants)

 Flood protection
– detention of water, natural flood walls (but can be flushed away)
– natural method to stabilize river banks

22
Q

Riparian Buffer Zones

A

See table slide 13

23
Q

Giving the River the Momentum of its own

A

 River beds and valleys have been shaped by erosion, transport and sedimentation – natural processes mainly driven by geology and climate/water.

 River beds have been altered by humans - no problem but:

 Degraded systems should be restored to achieve a selfsustaining, functional flow regime in the stream system that does not require periodic human intervention.