Spatial distribution of halobity in floodplain related to OM

accumulation

Gabriella Tóth, Amadé Halász, József Dezső, Jakub Miřijovský, Dénes Lóczy

Hungarian Scientific Research Fund

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Old-Drava Rehabilitation Programme (ODP) ”ecologically sustainable and cost-effective water supply”

Research area of Univ Pécs (2013-14)

Cún-Szaporca oxbow

„check the ODP plans”

planned pipe or channels

for water recharge and

regulation

lakes, oxbows under

revitalization

settlements

planned reservoirs

forests with

planned irrigation

arable with

planned irrigation

sluices

THE CÚN – SZAPORCA OXBOW

The planners* set the following criteria for the regulation of water level: • Water level fluctuation should not exceed 0.5 m within a year; • Water recharge should take place step by step, in divisions; • In a year water recharge should be implemented by not more than two

fillings; • The length of the filling period should remain within two weeks.

*In the planning document Old Drava Project

Problematic planning concept and calculations

• Success of water recharge is questionable: hydraulic connection not clear

• Quality of inflow water is different from that in the oxbow

• water quality parameters of Lake Kisinc are not pecisely known

Study area

• Area: 20 ha

• Length: 2 km

• Average latitude: 100 m

• Average depth: 1 m

•Lake Kisinc, one of the remains of the late Old- Drava bed •The bank is significantly covered with tangle

Problems

• Lack of water, water quality,

• Exploitation of the lake, aims (by planners):

• Protection of ecologycal/natural values, restitution of wetlands;

• ‘Establishment of sustainable water-management in the region’

• ‘Development of tourism and recreation’

Water supplement (plans)

90, 70 mBf 158 000 m3 A= 318525 m2 >>> 91,5 mBf (645 000 m3) A=635 000 m2

Water quality of Fekete-víz stream EC: 937 μS; DO: 5.72 mg/l; O2: 68.8%, KOI: 8.7 mg/l

Feeder canal

(under construction)

Water quality of Drava river (earlier natural water supplier, until 1976) EC: 283 μS; DO: 8.99 mg/l; O2: 101.1%, KOI: 4.1 mg/l

The aim

• Measure Lake Kisinc (oxbow), waterchemistry, the daily dynamism of the parameters (halobity)

• Is the condition suitable after a cool and rainy summer, by the measured parameters?

Mesotrophic condition Eutrophic condition

Phosphorous

µg/l 10-30

Phosphorous

µg/l 30-100

Total

nitrogen µg/l 400-600 Total

nitrogen µg/l 600-1500

Sampling

• water sampling for every hour in 24 hours from two

different depth:

30 cm

210 cm

Measurements

In field: Rapidly varying parameters: WTW 390i pH C° Redoxpotential Soluted O (mg/l, (%)

In laboratory: Nanocolor 500D VIS NH4

+, NO3- -- PO4 PO4-T KOI

2 4 6 8 10 12 14 16 18 20 22 241819202122237,0

7,2

7,4

7,6600

650

700

7501

2

3

410

20

30

40

5020

30

40

0,060,080,100,120,14

0,10

0,15

0,200,0

0,1

0,2

0,3

0,40

1

2

3

2 4 6 8 10 12 14 16 18 20 22 24

16

18

20

22

hours (210cm)

T(water) (°C)

pH

EC (µS)

O2 (mg/l)

O2 (%)

KOI (mg/l)

Orto-P (mg/l)

Total-P (mg/l)

nitrate (mg/l)

ammonium (mg/l)

T (air) (°C)

2 4 6 8 10 12 14 16 18 20 22 24

20

21

22

7,6

7,8

8,0540545550555560565

2

3

4

5102030405060

24

26

28

300,00

0,04

0,08

0,06

0,08

0,10

0,120,02

0,04

0,06

0,080,00,10,20,30,4

2 4 6 8 10 12 14 16 18 20 22 24

16

18

20

22

hours (30cm)

30cm

30

EC (µS)

O2 (mg/l)

O2 (%)

KOI (mg/l)

Orto-P (mg/l)

Total-P (mg/l)

nitrate (mg/l)

ammonium (mg/l)

T (air) (°C)

Classification

Results • No thermo-stratification

Oxygen:

ORP: -210 cm (kb – 30 mV)

O2: low (mg/l) also in saturation %

C circulation:

KOI: high

Phosphorous forms:

Orto- and total phosphate grate – adequate

Nitrogen forms:

nitrate, ammonium: great - tolerable

Conclusion 1. Bad water quality remains

2. Shallow depth: deeper layers (-210cm) heat up, low soluted O2 capacity

3. ORP: deeper layers are reductive (average: -30mV), high KOI: high organic matter content

4. Moderated transport of nutrients

5. The bigger water surface won’t owe adequate depth

6. Periodically refilling from Dráva river (I. class water quality): inland inundation

• Earlier investigations show similar results, most of the oxbows are at the same condition.

Thank you for your attention!

Hungarian Scientific Research Fund