What Is a Triangle Fan?

Arc delta refers to a geological phenomenon formed in the estuary area where the rivers entering the sea have high sand content, the channels are divided and frequently diverted, and the water depth outside the estuary is shallow.

The shoreline of this delta is reshaped by waves, and it is fan-shaped in plane form. It is mainly formed when the amount of sediment transported by the river reaches the vicinity of the estuary, the channel divides, the longitudinal ratio of the river bed decreases, the flow velocity decreases, and a large amount of sediment is deposited. With the diversion of the river multiple times, the entire delta coastline is continuously pushed to the sea. Such fan-shaped deltas are the most common in the world. Typical examples are the Nile,

The river flows into the sea with a lot of sediment, and the rivers on the delta change frequently, sometimes entering the sea in several shares. Sediment quickly accumulates in estuaries, forming large estuaries

Due to the special climate, geography, structural background of the estuary area, and the hydrodynamics of the Yellow River and aquifers, the Yellow River Delta has formed a unique sedimentary environment and sedimentary model. After field investigation and research, the Yellow River Delta is considered to be a highly constructive fan delta, which can be divided into delta plains, delta fronts, and pre-deltas. The delta plain includes microenvironments such as diverted river channels, abandoned river channels, banks, swamps, saline-alkali beaches, and aeolian sediments. The development of saline-alkali beaches in the Yellow River Delta plain is fundamentally different from the classic model of the Mississippi Delta. The delta front includes emblematic environments such as underwater diverted channels, underwater diverted bays, underwater natural dikes and breach fans, estuary sand dams, distant sand dams, and delta front mat sand. The modern study of the sedimentary environment and sedimentary model of the Yellow River Delta is of great significance to the study of ancient deltas and the development and management of the Yellow River Delta. ^[2]