Bed levelchange rate between cycle 2150 and 3200
Figure 11:apparentcorrelation between vegetation coverand relative bararea along the estuary,butwhy?
Sorghum Rumex Veronica
Figure 10:vegetation coverand estuary width along the estuary,there appearsto be no clearcorrelation.
Figure 7:estuarine bars/shoalsand theirrelation to vegetation presence.Yellow are bars,blue are channels and green isvegetation
Figure 9:Activity ofthe estuary between cycle 2150 and 3200.Ascan be seen the vegetated partisrela- tively unactive exceptforthe vegetation growth itselfand simultaneously the (to large)activity in the outerpartofthe estuary mightbe responsible forthe lack ofvegetation settlement.
Figure 8:bluenessimagesofan experimentwithoutvegetation (upper2)and with vegetation (lower2)after~2500 and ~9000 tidalcycles.The vegetated partofthe estuary hasbeen morpho- logically very stable compared to the simulation withoutvegetation.
Figure 6:vegetation appearsmainly in the innerpartofthe estuary with limited vegetation disappearing overtime (green isnew vegetation,red isdisappearing vegetation).
Figure 5:two tidalbarswith vegetation A)showshow itispositioned mid-channelwith surrounding mud.
B)showsdifferentvegetation speciesgrowin on the middle and edge ofthe bars
Area affected by vegetation settlement
Ai m 1: veget at i on devel opment
-Rumex hydrolapathum,Veronica beccabunga,Medicago sativa,Sorghum bicolorand Lotuspedunculatusgive promising results
-Large variability in shootand rootdevelopment
-Precise effectson bank erosion and ow resistance yetto be tested
Without vegetation
Pr el i mi nary concl usi ons
-Differentvegetation speciessettle in differentdepth zones
-More bare surface in widere reachesleadsto more vegetated area -Vegetation reducesmorphodynamics(and narrowsthe estuary?)
Figure 2:A,B:Friedkin set-up to testeffectofvegetation specieson bank erosion,water owing from the bottom leftchanneland eroding the sedimentblock.Q=500l/h S=0.02m/m using
timelapse photography to measure bank erosion rates.C:the differentpositionsofthe bankline overtime (blue initial,red after20 minutes).D:vegetation (Medicago sativa) changesthe erosionalprole.
I nt r oduct i on:
La
Large-scale planform shape and developmentofestuariesare partly deter- mined by saltmarsh and riparian vegetation.Thusfarthe biogeomorpho- logicalinteractionshave been studied mainly on marsh scale and rarely on the scale ofentire estuariesforlack ofsuitable modelsand scale experi-
ments.Here we develop the rst-everanalogue modelsofentire estuaries with mud and eco-engineering speciesto form mudatsand saltmarshes to investigate large-scale morphologicaleffects.
Ai m:
1.Find differentspeciesto representdifferenthabitats
2.Realistically spread seedsto simulate colonization patterns 3.Investigate effectson estuary shape and planform
Met hods:
Testvegetation species: -inundation resistance
-bank strengthening effects - ow resistance
Simulate estuariesin 20x3m tilting ume
Aim 3:estuary morphodynamics
Figure 1:testing the effectofwaterleveland seed burialon vegetation germination and development
Est uary scal e exper i ment s wi t h sal t mar sh veget at i on
I.R Lokhorst,G.van Buiten,S.I.de Lange,L.Braat,J.R.F.W.Leuven and M.G.Kleinhans
Fac.ofGeosciences,Dept.ofPhysicalGeography,UtrechtUniversity,the Netherlands.i.r.lokhorst@uu.nl
Ai m 2: veget at i on spr eadi ng
-Hydrochorously distributed vegetation
-Realistic colonization locationswhen released from river,no oodplain development -Sorting based on seed size and inundation tolerance
-Outerregion too active forcolonization
with
vegetation
Figure 3:20x3 metertilting ume tidalfacility
Figure 4:average shootand rootlength for5 promising speciesgrown under3 different waterconditionswithoutany nutrients.
A B
C D
