Changes

==Alluvial Fan and Its Classification==

==Alluvial Fan and Its Classification==

[[Alluvial]] deposits has gross – cone-like shape and form a convex-up construction in cross section. These deposits are consist of abudant gravel-sand detritus on mostly fairly steep depositional slope. They are poorly sorted and are common from the base of mountain range with many sediment supplies. Based on depositional processes, there are 2 kinds of alluvial fans, debris-flow-dominated fans and stream-flow-dominated fans. As the flow of sediments from high relief area (mountain range) comes to a lower area, they are free to spread out with help of gravity. Debris-flow deposits are poorly sorted with the lack of sediment structure, except the reverse graded bedding in their basal parts. They contain various sizes of sediment, and mostly impermeable and nonporous because of the high amount of muddy matrix.

[[Alluvial]] deposits has gross – cone-like shape and form a convex-up construction in [[cross section]]. These deposits are consist of abudant gravel-sand detritus on mostly fairly steep depositional slope. They are poorly sorted and are common from the base of mountain range with many sediment supplies. Based on depositional processes, there are 2 kinds of alluvial fans, debris-flow-dominated fans and stream-flow-dominated fans. As the flow of sediments from high relief area (mountain range) comes to a lower area, they are free to spread out with help of gravity. Debris-flow deposits are poorly sorted with the lack of sediment structure, except the reverse graded bedding in their basal parts. They contain various sizes of sediment, and mostly impermeable and nonporous because of the high amount of muddy matrix.

There is also mudflow which is similar to debris flow but mostly contains finer size of sediments than debris flow. Debris flow is also associated with landslide, the landslide is commonly as the source of sediments for debris flow. Stream-flow processes are the principal transport mechanism of stream-flow dominated fans. There are sheetflood and incised channel flow. Sheetflood is a broad expanse of unconfined , sediment-laden runoff water moving downslope , commonly proudced by catastrophic discharge. And incised-channel flow takes place through channel, 1-4 m high, incised into the upper fan.

There is also mudflow which is similar to debris flow but mostly contains finer size of sediments than debris flow. Debris flow is also associated with landslide, the landslide is commonly as the source of sediments for debris flow. Stream-flow processes are the principal transport mechanism of stream-flow dominated fans. There are sheetflood and incised channel flow. Sheetflood is a broad expanse of unconfined , sediment-laden runoff water moving downslope , commonly proudced by catastrophic discharge. And incised-channel flow takes place through channel, 1-4 m high, incised into the upper fan.