2. Measurements and results.2.1 General situation and description of measuredpoints within the research region

Backwater region near Zembrzycemeasurements:- distance 1800 [m] - 31 cross-sections- 6 cross-sections for measuring velocity (10 verticals each, 3-5 points per vertical)- 12 freezing probes of bed load from riverbed- 20 sieving probes of bed load from riverbed- 50 roughness hight measurements- 547 grains were collected for grain shape analysis

Using SENSA Z 300 velocity data can be measured twice per second and Using SENSA Z 300 velocity data can be measured twice per second and transmitted to PC. To measure bed roughness bigger than 2.5 cm AG-1 can be used.transmitted to PC. To measure bed roughness bigger than 2.5 cm AG-1 can be used.

profile-meter profile-meter AG-1AG-1

magneto-hydro-dynamical water magneto-hydro-dynamical water speedometer SENSA Z 300speedometer SENSA Z 300

Measuring instruments

Field measurementsField measurements – sample freezing – sample freezing

Traditional method of collecting probes of bed load Traditional method of collecting probes of bed load allow to describe only grains laying on the bed allow to describe only grains laying on the bed surface. Probe is disturbancesurface. Probe is disturbancedd. Sample freezing . Sample freezing method (using nitrogen) gives more benefits. The method (using nitrogen) gives more benefits. The probe is taken as layer in bed. The sieve curves are probe is taken as layer in bed. The sieve curves are made for few separate layers (about 10cm thick) made for few separate layers (about 10cm thick) starting from bed surface up to 0.4-0.5 m deep. This starting from bed surface up to 0.4-0.5 m deep. This gives possibility to describe bed change processes gives possibility to describe bed change processes which can be expected in treated river.which can be expected in treated river.

SKAWA, Zembrzyce - longitudinal profile - 2003

313.5

314

314.5

315

315.5

316

316.5

0 100 200 300 400 500 600 700 800

An example of the Skawa River in Zembrzyce waterlevel slope varies from 1 to 5 ‰ with average value in 2.9 ‰

2.2. Survey measurements

-cross-sections-longitudinal profile- water level

0

20

40

60

80100

120

140

160

180

stan Osielec stan Wadowice

alarm water levels in:

Osielec – 280 mm

Wadowice – 390 mm

2.3. Measurements of hydraulic parameters – velocity measurements

- velocity fluctuations

- velocity distribution in

cross-sections

- turbulence intensity

- velocity profiles0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 10 20 30 40 50 60

0.06

0.30

0.70

0.93

relativedistance from bedy/Y

time [sec]

velocity[ m / s ]

2.4. Granulometry of river bed

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

d [cm]

p [%]

2.6 Shape factor of grains

SF mean value SF min SF max [ - ] [ - ] [ - ] 0.38 0.14 0.77

Grain spherical coefficient p

>8 6-8 4-6 2-4 0-2grain shape / diameter [cm]grain contents [ % ]

spheroids 0.00 0.00 0.00 0.00 18.52flatten ellipsoids 0.00 0.00 17.65 4.55 7.41lengthened ellipsoids 0.00 33.33 23.53 6.82 3.70disks 11.11 0.00 23.53 15.91 18.52lengthen boards 33.33 33.33 11.76 29.55 25.93rods 55.56 33.33 23.53 43.18 25.93

Bed armouring processBed armouring process

141

145

150

Bartnik

N

n n Hhn

K1

2

1

1

badania laboratoryjneks = K (1.926 SF2 – 0.488 SF + 4.516)

koryta z piaskukoryta z piasku kkss = 2,9d = 2,9d9090

rumowisko gruberumowisko grube kkss = 3,5d = 3,5d8484

ziarna kulisteziarna kuliste k = 1,026dk = 1,026dmm szorstkość naturalnaszorstkość naturalna k = 2,85 dk = 2,85 d9090

Bed armouring processBed armouring process

ARMOUR PC PROGRAM – prognossis of sieve curve change:- Calculate dm

- Define the relation di/dm

- Calculate the non-dimensional shear stress fm on the basis of the standard deviation of the sieve curve

- For each di/dm value, define the grain-sheltering coefficient, and then calculate the non-dimensional shear stress fi for di

- For di calculate the critical shear stress tci according to equation (6)

- By Gessler’s method for ci/0 determine the probability of grain non-movement

- Read the percentage contents of a given fraction for each d i from the granulometric curve

- On the basis of an equation proposed by Gessler, obtain the granulometric curve (3) for conditions after the passage of flood.

Bed armouring processBed armouring process

q p c 0 /

Gessler’s function

max

min0

min0

)()(

)()()( d

d

di

da

dipdiq

dipdiqdip

Bed armouring processBed armouring process

bed surface acts on the flowing water

0

0.5

1

1.5

2

2.5

3

3.5

0 0.21 0.25 0.29 0.33 0.37 0.41 0.45 0.49 0.53 0.57

0.04

0.06

0.08

0.1

0.12

0.14

0.16 dm [m]

, c [kN/m2]

water depth [m]

c

dm

st.dev

3

4

5

6

7

8

9

0 0,5 1 1,5 2 2,5

depth[m]

p. Tenczynski