1.
Open channel, with bed slope >0
2211 AuAuQ 
Head loss
Reference line
𝑦1 + 𝑧1 +
𝑢1
2
2𝑔
= 𝑦2 + 𝑧2 +
𝑢2
2
2𝑔
+ ∆𝐻1−2
4

2.
u1
Reference [m]
Surfacelevel y +z [m]
Total Head H [m]
P1
z1
y1
u1
2/2g
P2
z2
y2
u2
2/2g
u2
21
2
2
22
2
1
11
22
 H
g
u
zy
g
u
zy
Head loss [m]
ΔH
Velocity Head [m]
Open channel, with bed slope <= 0
4

3.
e
b
y
lS
l ezz


3
0
3
22
2
b
e
SCB
Q
y


z1= Rise water level at distance l [m]
z0= Rise water level at weir [m]
l= Distance from weir [m]
Sb= Bed slope [1]
ye=equillibrium depth [m]
Back water profile [Stuwkrommen]
ye
Estimation!!!
4

4.
A critical depth B equilibrium depth
3
2
2
bg
q
y v
c


Back water profile [Stuwkrommen]
3
22
2
b
e
SCB
Q
y


4

5.
CU06997 Fluid Dynamics
Sediment transport
9.1 Introduction (page 282)
9.2 The threshold of movement (page 282-287)
9.3 A general description of the mechanics of sediment transport (p
282-292)
9.4 Sediment transport equations (page 292-304)
9.5 Concluding notes on sediment transport (page 304-307)
Just read the book, in this presentation just some general principles
1

6.
Sediment transport
• Erosion or scour
• Deposition / Sedimentation
Sediment transport
• By rolling or sliding along the bed (bigger
particles)
• By suspension in the moving fluid (smaller
particles)
Sediment transport is very complex
1

7.
Sediment transport turbulent flow
Rolling [rollen]
Sliding [glijden]
Saltation [Saltatie]
Suspend [Suspensie]
Dissolved [Opgelost]
2

8.
A schematic diagram of where the different types of sediment load
are carried in the flow. Dissolved load is not sediment: it is
composed of disassociated ions moving along with the flow. It
may, however, constitute a significant proportion (often several
percent, but occasionally greater than half) of the total amount of
material being transported by the stream.
http://en.wikipedia.org/wiki/Sediment_transport
2

9.
Sediment transport 3 steps
Step 1: Particles start to move (erosion / scour)
[Deeltjes komen los van bodem]
Step 2: Particles move horizontal (transport)
[Deeltjes worden (horizontaal) verplaatst
Step 3: Deposition of particles (sedimentation)
[ Deeltjes ‘vallen’ weer op de bodem]
1 2 3
2

10.
Parameters which influence erosion
Density Dichtheid
Grain size Korrel diameter
Shape Vorm
Cohesion Cohesie
Turbulence Turbulentie
Bed slope Talud helling (bodem)
Hydraulic Radius Hydraulische straal
2

11.
Erosion
𝜏 = 𝜌 ∙ 𝑔 ∙ 𝑅 ∙ S
τ = shear stress fluid [N/m2]
R = Hydraulic Radius [m]
S = Slope of channel bed [1]
Relation with mean boundary shear stress
Erosion, no relation with velocity???
Of course there is a relation with velocity, in
this case velocity is in the bed slope. A
steeper bed slope will give a higher velocity
Erosion will start to occur when the shear
stress caused by the flowing water is higher
than the critical shear stress of the material
2 vementMocr  movementnocr 

12.
Hulström diagram indicating erosion, transport or deposition
of sediment according to flow velocity and grain size
Erosion, Transport, Deposotion
2

13.
Table indication critical velocity
Soil type Critical velocity (m/s)
Clay
[klei, leem, löss]
0,60 …. 0,80
Clay and sand (Silt)
[zavel grond]
0,30 …. 0,60
Fine sand
[fijn zand]
0,15 …. 0,30
Coarse sand
[grof sand]
0,20 …. 0,50
Peat (fixed)
[vast veen]
0,30 …. 0,60
Peat
[slap veen]
0,15 …. 0,30
2

14.
Waves can make particles move (a bit) (back and forth)
Waves can’t make particles transport!!!
Combination current [stroming] and waves can make
particles transport easer!!
Effect of waves on erosion
2

15.
Transport capacity
• A river has a sediment transport capacity
or load. Transport capacity has a limit.
Important parameters are discharge, velocity
and turbulence.
• When the limit of transport capacity is
reached, new erosion will not occur
• When velocity decrease, transport capacity
will decrease. Sedimentation will occur
• When velocity increase, transport capacity
will increase. Erosion will occur
3

16.
sedimentation
Dam / weir
3
Transport