Hymo alterations – survey methods

European Union Water Initiative plus
for Eastern Partnership
© iStockphoto.com/ansonsaw
Support of Water Policy Reforms
towards Integrated Water Resources Management
WORKSHOP ON
ECOLOGICAL CLASSIFICATION
HYMO ALTERATIONS – SURVEY METHODS
Alexander Zinke
Kyiv, 19-20 June 2018
(based on presentations by the AT Ministry for Sustainability and Tourism)

Water status is defined by:
 Biological elements
 Chemical and physico-chemical elements supporting the biological elements and
 Hydromorphological elements supporting the biological elements
 Hydrological regime
• quantity and dynamics of water flow
• connection to groundwater bodies
 River continuity
• migration of aquatic species
• sediment transport
 Morphological conditions
• channel patterns, river depth and width variation
• flow velocities, substrate conditions,
• structure and condition of the riparian zone
WFD QUALITY ELEMENTS
2
Hydrology ContinuityMorphology
Photos:©Mühlmann

Hydromorphological pressures in Europe
Percentage of river water
bodies and lake water
bodies affected by
hydromorphological
alterations

HOW TO START?
Analysis of the general situation:
Main DRIVERS in AT Main PRESSURES in AT
Hydropower River continuity interruptions
Flood protection Morphological alterations of banks /soil
Navigation Impoundments / reservoirs
Urban development Water diversion / abstraction
(Agriculture) Hydro-peaking
4

HYDROMORPHOLOGICAL DATA –
LEVEL / SCALE ?
 water body level
or
 exact localisation (river km from – to)
or
 river segments with standardised length?
(i.e.100m, 500 m, 1 km 5km, 10 km, …)

Transversal barriers → continuity interruptions
Impoundments/reservoirs → reduced flow velocity
→ change of category
HYDROMORPHOLOGICAL PRESSURE TYPES
Hydrology:
• Water abstraction/diversion → reduced flows
• Water discharge → increased flows
• Hydropeaking → flow fluctuations
exact localisation
exact localisation
Morphology- physical degradation
• River regulation → river straigthening
• Flood defense works → bank fixation
• Land reclamation → soil fixation
standardised
500 m river stretch
(manageable uniformity)
exact localisation

HYDROLOGICAL ALTERATIONS AND
CONTINUITY INTERRUPTIONS
Why exact location of pressure?
• Easily available information (databases, licensing documents,
project documentations, …)
• Basis for water body delineation
• Basis for biological monitoring on impact (representative site)
• Basis for developing the Programme of Measures
• Overlapping alterations – multiple pressures
7

ASSESSING HYDROLOGICAL ALTERATIONS –
1.1 WATER ABSTRACTION
Register and assess:
- All water stretches between abstraction point and return of flow
- in case of diversions: all water stretches between abstraction point and
next confluence with a larger river
Austrian Ordinance on Ecological Status Assessment:
• Only marginal abstraction (defined values of E-Flow) → high status
• Basic flow + dynamic share (defined values of E-Flow) → good status
• If criteria for good status are exceeded: significant water abstraction
8

Water Abstraction
Water stretches between abstraction point and return of flow or confluence with a
larger river
Point of water
abstraction
Return of
flow
Austria: Driver for water abstraction
mainly Hydropower:
ca. 2500 diversion plants, >85% without
ecological minimum flow

ECOLOGICAL MINIMUM FLOW
AT Ordinance on Ecological Status Assessment:
Achievement of GES depends on two aspects:
Basic flow must be available in a water body at all times to ensure
• preservation of WB type and habitats – natural mean daily low flow (NQt)
• river continuity - minimum depth and minimum flow velocity
Dynamic share reflecting the natural discharge dynamics over the year to
ensure
• natural bed-sediment relocation, type-specific substrate,
• sufficient stream velocity in times of spawning migrations
• different habitat demands of individual age classes of key organisms
• type-specific oxygen and thermal conditions
• recommended value: 20% of natural discharge
10

ASSESSING HYDROLOGICAL ALTERATIONS –
1.2 HYDRO PEAKING
This refers to all water stretches with surge/downsurge phenomena
caused by (pumped) storage power plants
• No or only marginal surge/downsurge phenomena: high status
• Maximum ration of 1:3 between downsurge and surge, or
• at least 80 % of river bed covered during downsurge: good status
If criteria for good status are exceeded: significant pressure
11

Monotonous river courses - deficits in habitats
Populations stressed by strong hydro-peaking
Blocked longitudinal migration
Figure: LIFE
monitoring report

13
Surge / downsurge effects
Restoration
measures:
• Balance reservoirs
• Reduction of
downsurge velocity
• …? (study)
Water level fluctuation
Surge/downsurge
amplitude
Hydrological alteration
Flow variations (water level
fluctuations)

ASSESSING HYDROLOG. ALTERATIONS:
1.3 IMPOUNDMENTS / RESERVOIRS
Assess every river stretch with an anthropogenic reduction of the mean
flow velocity in the cross-section down to 0.3 m/s at annual mean flow
• Only occasional anthropogenic reductions of the mean flow velocity and only at
very short stretches → high status
• Anthropogenic reductions of the mean flow velocity in the cross-section of below
0.3 m/s at annual mean flow (MQ) occur only at very short stretches. → good
status
Impoundments ecologically relevant:
rivers > 100 km² catchment size: 500 m length
rivers 10 – 100 km² catchment size: 100 m length
If criteria for good status exceeded: significant pressure
14

HYDROMORPHOLOGICAL ALTERATION -
IMPOUNDMENT
15
 Reduction of flow velocity
 Altered sediment transport
 Loss of river character
Restoration measures:
Improvement of habitat diversity in particular
in the upper part of impoundment

Hanging structure with tires Embedding crushed rocks Binding soil layer on gravel
Reshaping and
willow rolls
Vegetation growth
after several seasons
Rehabilitation of impounded sections
Example Feistritz reservoir – Rehabilitation of dike crest
© Verbund AHP - DHI Sabine Käfer 2009

2. ASSESSING RIVER CONTINUITY
Assess causes of a migration barrier for aquatic fauna and sediment:
- Each artificial (and natural) structure
- Each stretch with water abstraction
• Unhampered migration of type-specific aquatic organisms and the natural
transport of sediments in the streambed → high status
• Anthropogenic migration barriers occurring in the natural fish habitat must be
passable for fish all year long. Human impact on habitat connection
shall only be marginal. → good status
Each single migration barrier (e.g. >1m) is a significant pressure
17

ASSESSING RIVER CONTINUITY
Verify each potential migration barrier via field check.
Passability depends on height and design of stucture, its supply
with water, its connection with up- and downstream water body.
18

CONTINUITY INTERRUPTIONS - MIGRATION BARRIERS

Continuity interruptions
Migration barriers – ecological fragmentation
Fish passes
Solution measures:
Re-constructing ramps
instead of weirs

Examples for assessment of passability of structures
No water –
not
passable
Free fall – not passable
Thin water lamella – not
passable
Also stretches with
residual flow can be
a migration barrier!
Assessment examples – River Continuity

Also structures with low heights can be a migration barrier → individual
assessment for every potential migration barrier necessary
Passability depends on:
 Height of structure
 Coverage of structure with water
 Does water descend in a chute (fish can swim through it) or as a free
falling jet of water?
 Is the water lamella thick enough to swim through?

Assessing passability of structures
Thick and not free falling water lamella –
passable for (strong) fish.
Thick water lamella between rocks.
Fish can swim through.
Barrier passable due to fish migration
structure.
© EZB

HYDRO BARRIERS AND RIVER CONTINUITY
ALONG THE INTERNATIONAL DRAVA RIVER
24 hydrodams: 0.1 – 126 MW
1 in Italy
12 in Austria (1 peak)
8 in Slovenia (2 peak/bypass)
3 in Croatia (3 peak/bypass)
Fish passes: Few functional /
operating in 2014
New fishpass: Rottau dam (Möll river)
Edling dam (Drava river) Photos: Zinke

Restoration of the river
continuity
Fish pass by 2021
Fish pass by 2015
Fish passage exists

3. Morphological alterations
(physical degradation)
3.1 Straightening, channelisation,
bank / soil fixation
Ecological effect:
monotonous structures, habitat losses

3.2 ALTERATIONS OF BANK DYNAMICS
Bank dynamics indicate in 5 classes a river's capacity to
• change and reconfigure the typical river course and
• develop type-specific bank structures crucial for habitat diversity:
• undercut and glide slope banks
• erosion banks
• banks with flat and steep embankments
• wash-outs
• woody plant structures and root network in the riparian zone.
Bank “protection measures” limit these river capacities
27
habitat
diversity

Assessing Bank Dynamics
Bank dynamics are a river's capacity to change and reconfigure the typical river
course and its capacity to develop type-specific bank structures, such as
• undercut and glide slope banks
• erosion banks
• banks with flat and steep embankments
• wash-outs
• woody plant structures and root network in the riparian zone
Bank structuring and “protection” measures limit the river’s capacities to develop
type-specific bank structures and to form its riparian zone.
Habitat
diversity
Assessment examples – Bank Dynamics

Morphology classes for bank dynamics and riverbed dynamics:
Parameters MORPHOLOGICAL CONDITIONS
bank dynamics planform structures in river bed
river bed dynamics substrate composition riparian vegetation
Main morphological
parameters;
assessment compulsory
Additional morphological paramaters for refinement;
assessment not compulsory
class 1 class 2 class 5class 3 class 4
Bank
dynamics
River bed
dynamics
Assessment examples – Bank & Bed Dynamics

AT Assessment of Morphological Alterations
 5-class assessment system
 Assessment of morphological status for pre-defined 500m-stretches
 The larger the deviation from reference condition, the worse the rating of the river stretch
 Assessment must be type-specific!
1: Definitely
no ecological
problem
2: Some
pressures
but
ecologically
still ok
3: There
might be an
ecological
problem =>
monitoring!
4: Definitely
an ecological
problem
5: No
ecological
function
possible
Impact on ecology::

Recordings – Data Entry Form

• All data on hydromorphological
pressures in Austria in one
database
• Online access for registered
users
• Map-display of all pressures, risk
assessment and ecological status
• Database easy
to keep
updated
National Database on
Hydromorphological Pressures

At risk Possibly at risk
REDUCED FLOW
(water
abstraction/diversion)
< Mean low Qt residual flow unknown
FLOW VARIATION
Large rivers
small and medium rivers
flow amplitude
> 1: 1
> 1:5 or unknown
-
RISK CRITERIA
Risk Assessment – Criteria Hydromorphology (1)

At risk Possibly at risk
IMPOUNDMENTS
(length of backwater
with reduced flow
velocity)
> 1 000 m or
> 30% of water body length
500 – 1000 m or
10-30% of WB length
MIGRATION
BARRIER
transverse structures
not passable for fish
Highland rivers: > 70
cm
Lowland rivers > 30 cm
1 or more
RIVER
MORPHOLOGY
(5-class system)
> 70% morphol. class 3-5
or
> 30% morphol. class 4-5
30%-70%
Morpholog. class 3-5
RISK CRITERIA
Risk Assessment – Criteria Hydromorphology (2)

Hydromorphologie
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
G
esam
trisiko
A
llg.chem
.-pyhsikal.P
aram
eter
C
hem
ische
S
chadstoffe
H
ydrom
orphologie
R
estw
asser
S
chw
all
S
tau
Q
uerbauw
erke
M
orphologie
%derWasserkörperlänge
Risiko Risiko nicht einstufbar kein Risiko
AT Risk Assessment 2004/2007 (rivers > 10 km2)
At risk Possibly at risk Not at risk
---------- Hydromorphology----------
Impact - pressure
relation
Reduced flow:
(water abstraction)
flow variation
(hydropeaking)
Reduced flow velocity
& change of category
(impoundment)

Hydromorphology and ecological status
Austrian Methodology
Water abstraction: 10%impoundments:
4%
Hydro peaking 2%
Ecological status/potential
of rivers > 10 km2
(2014)
Morphological
alterations: 30%
Migration barriers: 32.000 (1/km)

IMPROVING RIVERINE
ECOLOGY WHILE
MAINTAINING OR
IMPROVING NAVIGABILITY
Restored river banks
Reconnected
side-arms
Down-sized
groynes
Photo: B. Boekhoven, RWS-NL
Photos: via donau

Restoration at
Obergottesfeld
(river Drau)
Opening in 2011
Rework in 2014
Photo. Zinke Photo. AKL / Tichy
Photo: Revital

Flood Protection
Drava river restoration
projects have improved…
Retention Areas
Morphological Dynamics
Aquatic Habitats
Recreation Areas
Non Aquatic Habitats
River Widening at Obergottesfeld

Hymo alterations – survey methods

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