Sedimentary Response of a Fingered Bar-Type Shoal Water Delta to Lake Level Fluctuations:Insights from Flume Tank Experiments
The finger-bar-type shoal water delta is composed of one or more finger bar composed of mouth bar-natural levee-river channel.This type of delta develops in lake or sea basins with shallow water bodies,rela-tively stable tectonics,and frequent horizontal fluctuations.This study aims to explore the relationship between frequent lake level fluctuations and the development of finger-bar-type shoal water deltas,along with the forma-tion and response mechanism of their internal sedimentary units.A flume tank experiment was conducted to simulate the development and evolution of bar finger under conditions of frequent lake level rise and fall.The simulation experiments were designed for a 18-cycle model of lake level fluctuations during alternating flood and dry periods.The experiment lasted 108 hours,involving precise monitoring of sedimentary geomorphology and quantitative sedimentological analysis using a 3D laser scanner.The river channel,mouth bar,and natural levee are interrelated and interact with one another.The river channel carries sediments that form a mouth bar at the river mouth,which gradually accumulates and transforms into a natural levee.The solid natural levee re-duces the frequency of channel oscillation,allowing the river channel to continuously transport and extend sedi-ments into the lake area.The development of a single-channel finger-bar-type shoal water delta is controlled by the dynamic balance among the river channel,natural levee,and mouth bar,as well as the periodic water level cycles.Additionally,the flow accelerates the establishment of this balanced relationship.The development of the finger-bar-type shoal water delta is characterized by sediment accumulation primarily at the river mouth and strip-like denudation of the river channel.Inconsistent sediment unloading on either side of the estuary cause the river channel to oscillate from side to side.The analysis of the experimental data reveals changes in the sed-imentary response of the finger-bar-type shoal water delta.The study summarized the dynamic evolution pattern of its internal units,providing a valuable reference for understanding shoal water delta evolution and for the ex-ploration and development of similar oil and gas reservoirs.
shoal water deltafinger barflume tank experimentsedimentary process
万方数据
维普
