MODELIRANJE
PREMEŠČANJA PLAVIN NA NIVOJU POVODJA
SEDIMENT DYNAMICS MODELLING AT BASIN SCALE
Gregor Petkovšek
Izvleček
V članku je predstavljen
enodimenzijski matematični model premeščanja rinjenih plavin na nivoju povodja.
Sedimentološki in hidravlični del sta ločena. Sedimentološki del modela je frakcijski,
s čimer je omogočena simulacija procesov razvrščanja plavin. Pri tem račun
premeščanja rinjenih plavin temelji na Hunzikerjevih enačbah, kontinuitetna enačba za
zrnavost izmenjevalnega sloja pa je privzeta po Hiranu. Vgrajen je tudi model obrabe
plavin, kar je glavna razlika v primerjavi s Hunzikerjevim modelom MORMO. Hidravlični del
modela omogoča račun stalnega mirnega neenakomernega toka v strugi s spremenljivo
širino dna, pri čemer se ne upošteva upor brežin. Mogoč je stranski dotok vode in
plavin v poljubni količini in zrnavosti. Model z vsemi naštetimi komponentami je
primeren za simulacijo pojavov iz hidrotehnične prakse, kot so zaprojevanje akumulacij,
erozija rečnih strug zaradi povečane premestitvene zmogljivosti ali prekinjenega dotoka
plavin in podobno. Model je bil testiran z Günterjevimi
laboratorijskimi poskusi in je pokazal dobro ujemanje v vseh merjenih količinah. Kot
primer uporabe na nivoju povodja je podan izvleček rezultatov simulacije povodja Save
Dolinke nad prodnim zadrževalnikom Hrušica, z upoštevanjem njenih glavnih
pritokov.
Ključne besede: rinjene plavine, frakcijski model, obraba plavin, pritoki,
1D model
Izvirni znanstveni članek UDK 519.87:627.132
Abstract
A one-dimensional mathematical basin-scale model of sediment dynamics
is presented in the paper. The model is decoupled. Computation by fractions is introduced
in the sediment portion in order to simulate sediment sorting. Bed load equations follow
the Hunziker concept, while for sediment routing, Hirano's concept of active layer is
applied. The size-mass balance wear model is also included, which creates the main
difference with respect to Hunziker's model MORMO. The hydraulic portion is designed to
solve steady non-uniform flow cases (sub-critical regime only), with variations in river
bed width, while the channel bank friction is not implemented, i.e. the wide bed
hypothesis in supposed. Tributary inflow of both water and sediments of any quantity and
granularity is also possible. The model set up in the described way is capable of solving
practical problems such as reservoir sedimentation, river bed erosion, etc. The model was
tested using the results of Günter's laboratory experiments, and showed good agreement in
all the quantities measured. To demonstrate the model's basin-scale capabilities, a
simulation of the Sava Dolinka watershed upstream from the Hrušica sediment retention
basin is briefly presented.
Key words: bed load, computation by fractions, wear,
tributaries, 1D model
Scientific paper UDK 519.87:627.132