1. Seppo Hellsten & Teemu Ulvi
Oulujoki Pilot River Basin – Provisional Designation of Heavily Modified Rivers and Lakes
Seppo Hellsten & Teemu Ulvi

2. area km2
lake percentage 11.4 %
mean annual discharge 259 m3/s
number of lakes 502
number of rivers 85

3. Introduction Typical representative of Nordic problems
Relatively good water quality and a lot of pristine waters
Scarcity of population > less than 12 inh./km2
Few point source pollution – usually under control
Diffuse loading from agriculture and forestry
Extensive use for hydropower with parallel benefit for flood defence
Hydropower production plays important role by modifying water bodies
smaller modifications caused by clearing of rivers for timber floating
hydromorphological pressures are playing an important role

4. Eutrophic lakes in Oulujoki Catchment (Lepistö et al., 2000)

5. Regulated lakes and hydropower plants# 5 1 K i l o m e t r s N
18 plants > 550 MW
1400 km2 regulated lakes
construction efficiency > 80 % N

7. GENERAL VIEWS OF HYDROMORPHOLOGICAL PRESSURES OF RIVER OULUJOKI
Morphological changes are poorly documented and general database is not available
Projects have taken place a long time ago => timber floating, drainage works, flood protection, hydropower
A lot of manual works needed
Hydrological databases are covering largest lakes and main rivers
Recalculated natural values and on-line data are available
A proper basis for estimation
ASSUMPTION: Morphological pressures plays significant role in small rivers, hydrological in larger ones and lakes

8. How to find a simple HyMO-pressure estimation procedure?
Needed factors should be determined:
Hydrological status
Morphological status
River continuum
Estimation procedure should be realistic and without any extra financial demands
Multiphase approach

9. APPROACH FOR IDENTIFICATION HyMo PRESSURES AND HMWBs
PHASE 1: IDENTIFICATION OF PRESSURES (PRE-SCREENING) Pressures are identified and their significance are estimated in a broad scale (expert judgement)
WBs where HyMo-
pressures
are of minor
importance
WBs where HyMo-
pressures are non-significant
PHASE 2: ASSESSMENT OF THE PRESSURES Further analysis of significance of pressures based on the HyMo criteria Data collection
PHASE 3: PROVISIONAL DESIGNATION Criteria for regulated and constructed lakes and rivers
Provisonally heavily modified WBs

10. RIVERS PHASE 1. IDENTIFICATION OF PRESSURES (PRE-SCREENING)
No pressures (class 0), minor pressures (class A), significant pressures (class B)

11. PHASE 2: ASSESSMENT OF THE PRESSURES

12. PHASE 3: PROVISIONAL DESIGNATION (HCMo-model)
Listing of Hydrological, Continuity and Morphological indices from phase 2
Calculation of alteration indices (AI)
AI = (Hi/n+ Ci/n + Moi/n)/3,
where H=hydrological factors (i= 1-n),
C = continuity factors (i= 1-n)
Mo = morphological factors (i= 1-n) and n = total amount of alteration factors.

13. Changes Scoring HYDROLOGY CONTINUITY MORPHOLOGY Alteration index 10
River Muhosjoki
59 km
Changes
Scoring
name of project, detalls
Very sign. change=4, sign. change
=3, moderate=2
small change=1, no change=0
HYDROLOGY
A. Mean discharge change (MQ) -
B. Change in daily discharge
change in flood peak 1
C. Change in flood peak
CONTINUITY
A. Dams and weirs – other factors
preventing animal and sediment
movement
8 weirs and bridges 3
MORPHOLOGY
A. Changes in structure of river bed
Dredging 2
B. Longitudial changes (meanders etc.)
cut-offs
C. Bank changes
embankmentst
Alteration index 10
Out of maximum value
27.8

14. Comparison HCMo / RHS River Muhosjoki 100.0 y = 1.9833x + 3.371 80.0 R2 =
60.0
HCMo (%)
40.0
20.0
0.0
0.0
10.0
20.0
30.0
40.0
50.0
HMS (%)
Comparison HCMo / RHS

15. Preliminary results
Main stream of River Oulujoki is provisionally designated as HMWB
Smaller rivers are not significantly modified

16. LAKES Similar three phase approach
Morphological pressures are evaluated only in lakes smaller than 10 km2
Hydrological pressures are the most important in large lakes

17. Typical lake regulation

18. PHASE 3. IDENTIFICATION OF HMWBs 1. step
Classification of lakes based on lake-percentage of watershed
2 criteria; winter draw-down and extension of spring flood
WATER LEVEL FLUCTUATION SIMILAR
TO NATURAL
WATER LEVEL FLUCTUATION
DEVIATING FROM NATURAL
NATURAL WATERBODY
LAKES WITH HIGH HYDROLOGICAL STATUS
Result:
20 % of 105 regulated lakes were at high hydrological status
WATER LEVEL FLUCTUATION IN NON-REGULATED LAKES

19. IDENTIFICATION OF HMWBs 2. step
Classification of lakes based on lake-percentage of watershed
2 criteria; winter draw-down and extension of spring flood
WATER LEVEL FLUCTUATION SIMILAR
TO NATURAL
WATER LEVEL FLUCTUATION
DEVIATING FROM NATURAL
MAGNITUDE OF DEVIATION
3 criteria; water-level raise/draw-down,
winter draw-down and extension of spring flood
NO FILLED CRITERIA
AT LEAST ONE CRITERIA FILLED
NATURAL WATERBODY
Results:
10 lakes of 42 deviated with low values
4 lakes of 42 deviated with high values
CRITERIA Increase in winter draw-down 1,5 m or 3 m Decrease in spring flood 0,7 m or 1,2 m Increase/decrease in mean water > 1 m

20. MACROPHYTES (LARGE ISOETIDS) COMPOSITION
> 3 metres
GOOD
MODERATE
ZOOBENTHOS COMPOSITION
> 3 metres
REGULATED LAKES
NATURAL LAKES

21. Preliminary results HMWB-lakes
With strict criteria: Lakes Vuokkijärvi and Iso-Pyhäntä
With mild criteria: Lakes Ontojärvi and Kiantajärvi
Some borderline cases

22. Conclusions
Provisional designation gives relatively similar results than expert judgement
Biological response is especially in rivers unclear
biological classification is still missing
difficult to distinguish different pressures in rivers