Volume 2 - International Environmental Modelling and Software ...

4. PREDICTION OF OUTCOMES
The outcomes of rehabilitation measures are difficult
to predict. As rehabilitation measures usually
directly affect the shape of the river bed, the most
direct consequences consist of hydraulic and
morphological changes. These then have consequences
on the benthic population, fish,
vegetation, and shoreline community. In addition,
they have social and economic consequences.
These relationships are visualized in Fig. 2.
Nat. ecosystem
function
Nat. population
stability
Functioning
organic cycles
Density of
refugia
Mean primary
productivity
Number of nat.
tributaries p.r.l.
Mean leaf decomposition
rate
Mean respiration
rate
Ecosystem
integrity
Natural benthic
community div.
Mean density
of algae
Mean density of
grazers & collect.
Mean density
of shredders
Mean density
of predators
Natural fish
diversity
Abundance
of trout
Abundance
of barbel
Nat. species
diversity
Abundance
of nase
Natural vegetation
diversity
Area of pioneer
vegetation p.r.l.
Area of soft wood
vegetation p.r.l.
Area of hard wood
vegetation p.r.l.
Area of gravel
bars p.r.l.
Natural shoreline
community div.
Mean density of
carabid beetles
Mean density
of spiders
Landscape
integrity
Mean density
of ants
Natural morphological
type
Morphological
type
Natural spatial
variability
Coef. of variation
of water depth
Coef. of variation
of flow velocity
Nat. river
morphology
High connectivity
(long., lat., vert.)
Length of
connected reach
Fraction of natural
river banks
Ratio of bank
to river length
Fraction of fine
sediments
Natural floodplain
morphology
Average
floodplain width
Natural flood
characteristics
Discharge of
annual flood
Number of delam.
floods per season
Hydrogeomorphic
integrity
Nat. discharge
regime
Natural low
water periods
Average
discharge.
5% fractile of
discharge distrib.
Rehabilitated
river section
Absence of artificial
fluctuations
Natural temperature
regime
Amplitude and
period of fluct.
Long term/seasonal
temp. change
Rate of increase/decrease
Amplitude of short
term temp. fluct.
Low suspended
sediment conc.
Mean susp. sed.
conc. at low disch.
Good water
quality
High oxygen
concentration
Min. dissolved
oxygen conc.
Natural nutrient
concentrations
Mean phosphate
concentration
Mean inorg.
nitrogen conc.
Low pollutant
concentrations
Mean metal
concentrations
Mean organic
pollutant conc.
High flood retention
capacity
Expected
damage cost
Retention
volume p.r.l
Ensuring ecosystem
services
Good w. quant./
qual. at gw. wells
High self-purification
capacity
Groundwater recharge
rate p.r.l.
Reaeration
coefficient
Groundwater
infilt./transp. time.
High recreational
value
Area of accessible
gravel bars p.r.l.
Socio-economic
well-being
Low implem. cost
(constr., maint)
Low construction
cost
Low maintenance
cost
Construction cost
per year, p.r.l
Maintenance cost
per year, p.r.l.
Guaranteeing job
opportunities
Guaranteeing
agricultural jobs
Guaranteeing
non-agri. jobs
Change in no. of
agricult. jobs
Change in no. of
non-agri. jobs
Figure 1.
Objectives hierarchy (rectangular boxes and lines) and attributes (rhombic boxes) corresponding to the
lowest-level objectives for a rehabilitated river section (p.r.l. = per unit river length).
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