Reactivating bed load transport in Swiss rivers Reactivating bed ...
Reactivating bed load transport in Swiss rivers Reactivating bed ...
Reactivating bed load transport in Swiss rivers Reactivating bed ...
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<strong>Reactivat<strong>in</strong>g</strong> <strong>bed</strong> <strong>load</strong> <strong>transport</strong> <strong>in</strong><br />
<strong>Swiss</strong> <strong>rivers</strong><br />
Strategic plann<strong>in</strong>g and examples of implmentation<br />
Dr. Lukas Hunz<strong>in</strong>ger<br />
Flussbau AG SAH<br />
dipl. Ing. ETH/SIA flussbau.ch
2<br />
Outl<strong>in</strong>e<br />
� Hystory of the <strong>bed</strong> <strong>load</strong> balance <strong>in</strong> <strong>Swiss</strong> <strong>rivers</strong><br />
� New federal act on the protection of waters<br />
� Strategic plann<strong>in</strong>g<br />
� Alp-Sihl-Limmat: an example
3<br />
Hystory of <strong>bed</strong> <strong>load</strong> balance <strong>in</strong> <strong>Swiss</strong> <strong>rivers</strong><br />
Emme Lützelflüh, 1780
4<br />
Narrow<strong>in</strong>g of river <strong>bed</strong>s
5<br />
Sediment retention <strong>in</strong> the catchment areas
6<br />
Channelised <strong>rivers</strong> suffer from <strong>bed</strong> erosion
7<br />
Bed <strong>load</strong> deficits relative to natural <strong>load</strong><br />
0-20 %<br />
20-50 %<br />
50-80 %<br />
80-100 %<br />
2011
8<br />
New federal act on protection of waters<br />
� Def<strong>in</strong>e the space provided for water courses<br />
� Plan and perform river restorations<br />
� Reduce the harmful effects of hydropeak<strong>in</strong>g<br />
� Reduce the harmful effects of <strong>in</strong>stallations on fish<br />
migration<br />
� Reduce the harmful effects of <strong>in</strong>stallations on the <strong>bed</strong><br />
<strong>load</strong> balance
9<br />
New federal act on protection of waters<br />
� Def<strong>in</strong>e the space provided for water courses<br />
� Plan and perform river restorations<br />
� Prevent the harmful effects of hydropeak<strong>in</strong>g<br />
� Prevent the harmful effects of <strong>in</strong>stallations on fish<br />
migration<br />
� Prevent the harmful effects of <strong>in</strong>stallations on the <strong>bed</strong><br />
<strong>load</strong> balance<br />
‣ To remediate <strong>in</strong>stallations
10<br />
Installations with an an impact on the <strong>bed</strong> <strong>load</strong><br />
balance<br />
� River control prevents<br />
mobilisation
11<br />
Installations with an an impact on the <strong>bed</strong> <strong>load</strong><br />
balance<br />
� Dragg<strong>in</strong>g, gravel traps<br />
and dams prevent <strong>transport</strong>
12<br />
Installations with an an impact on the <strong>bed</strong> <strong>load</strong><br />
balance<br />
� Narrow channels prevent aggradation
13<br />
Reduce Reduce the harmful effects on the <strong>bed</strong> <strong>load</strong><br />
balance<br />
� Targets:<br />
� Indicators:
14<br />
New federal act on protection of waters<br />
� Strategic plann<strong>in</strong>g on cantonal level (until 2014)<br />
� Project plann<strong>in</strong>g, implementation and monitor<strong>in</strong>g by<br />
cantons, municipalities and hydro power companies<br />
(until 2034)<br />
� F<strong>in</strong>ancial contribution<br />
– <strong>Swiss</strong> grid<br />
– Federal subsidies
15<br />
Strategic plann<strong>in</strong>g<br />
� Goal:<br />
– Installations def<strong>in</strong>ed where remediation is mandatory<br />
� Challenges:<br />
– Great number of water courses and <strong>in</strong>stallations<br />
– Timeframe<br />
– Criteria to determ<strong>in</strong>e obligation<br />
– Decentralised competencies
16<br />
Strategic plann<strong>in</strong>g: solutions<br />
� Selection criteria<br />
example Canton Bern:<br />
40 river strechtes<br />
watershed ≥ 100 km 2<br />
Elaboration of<br />
methodology <strong>in</strong> 5 streams
17<br />
Methodology
18<br />
When is the <strong>bed</strong> <strong>load</strong> balance distur<strong>bed</strong>?<br />
Alp - Sihl - Limmat <strong>rivers</strong>
19<br />
Alp - Sihl - Limmat <strong>rivers</strong>
20<br />
Annual <strong>bed</strong> <strong>load</strong><br />
Current stage<br />
Initial stage<br />
Required <strong>bed</strong> <strong>load</strong>
21<br />
Gravel bars at an <strong>in</strong>itial stage (Alp 1890)<br />
Average bar surface: 5'600 m 2<br />
# bar sequences: 2<br />
Mix<strong>in</strong>g layer: 0.3 m<br />
Required <strong>bed</strong> <strong>load</strong>:<br />
5'600 x 2 x 0.3 ≈ 3'400 m 3
22<br />
Gravel bars at an <strong>in</strong>itial stage (Limmat 1850)<br />
Average bar surface: 3'800 m 2<br />
# bar sequences: 1<br />
Mix<strong>in</strong>g layer: 0.3 m<br />
Required <strong>bed</strong> <strong>load</strong>:<br />
3'800 x 1 x 0.3 ≈ 1'200 m 3
23<br />
Measures proposed<br />
� Adjuste managament of gravel traps<br />
� Reduce excavation<br />
� Extract and dump<br />
� Modify weirs<br />
� Lower water level at<br />
weirs dur<strong>in</strong>g floods
24<br />
Dump<strong>in</strong>g of gravel (Limmat 2011)
25<br />
Annual <strong>bed</strong> <strong>load</strong> with measures<br />
Current stage<br />
Initial stage<br />
Bed <strong>load</strong> with<br />
measures
26<br />
Dump<strong>in</strong>g of gravel (Aare 2005)
27<br />
Monitor<strong>in</strong>g the effects of gravel dump<strong>in</strong>g<br />
Extension of gravel bars downstream 1998, 2000, 2006, 2008, 2011
28<br />
Monitor<strong>in</strong>g the effects of gravel dump<strong>in</strong>g<br />
Number of grayl<strong>in</strong>g larvae (Thymallus thymallus) 2005-2009
29<br />
Summary<br />
� Hystory of the <strong>bed</strong> <strong>load</strong> balance <strong>in</strong> <strong>Swiss</strong> <strong>rivers</strong><br />
� New federal act on the protection of waters<br />
� Strategic plann<strong>in</strong>g<br />
� Alp-Sihl-Limmat: an example
30<br />
About the questions<br />
� Policy framework<br />
CH: new act, new funds<br />
� Climate change and sediment <strong>transport</strong><br />
Increased yield <strong>in</strong> upper catchment areas - management<br />
of debris <strong>in</strong> sediment traps<br />
� Knowledge gaps<br />
Gap between hydraulic modell<strong>in</strong>g techniques and empiric<br />
<strong>transport</strong> formulae<br />
� Knowledge on the status on sediment regime<br />
CH: <strong>in</strong> large <strong>rivers</strong> cross sections observed, small streams not
31<br />
About the questions<br />
� Siltation<br />
As widespread as channelised streams with armoured layers<br />
� Artificial floods<br />
Floods to mobilise <strong>bed</strong> <strong>load</strong><br />
Are effects of floods killed by low residual flow?<br />
� Reservoir flush<strong>in</strong>g<br />
Small scale flush<strong>in</strong>gs are widespread<br />
Large scale flush<strong>in</strong>gs (ex. Verbois) are not
32<br />
Thank you