The Arctic’s Largest Delta

[multiweb (Marc)]

Some superb imagery here.

https://www.youtube.com/watch?v=4Hp47laLjYs

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[AstralTraveller (David)]

Hi,

Yes, lovely images of what I believe is still a wilderness. Also, I don't think there is a dam or any other flow control on the river - flow control will alter delta morphology. So, it's probably as pristine as anywhere on Earth.

Delta morphology is controlled by three factors: river flow, wave action and tidal action (see, for example https://www.e-education.psu.edu/earth107/node/1023, https://www.researchgate.net/figure/...fig3_275640337) I can't see any indication of tidal influence, which I think is right in that part of the world. The inner section of the delta looks flow dominated but the outer edge is truncated indicating wave control. It's interesting that the delta is only influenced by conditions during summer as it is frozen solid in winter.

[multiweb (Marc)]

Souns like a very dynamic area. I thought deltas were mostly static but you're right, between the tidal sea, rivers and erosion that's a lot interaction. The only sure thing is that it must be a mozzie heaven. Sweden in summer is no better if that's anything to go by. No need for aerogard. A tennis racket is more appropriate.

[AstralTraveller (David)]

I suspect that deltas are one of the more dynamic parts of the natural environment. Some of them, at the mouth of rivers with large flow and sediment supply, were naturally quite dynamic but human impacts are making more of them change.

Probably the most dynamic delta is the Huang He in China (the yellow river) which drains the poorly-consolidated loess plateau. It has built 2,200km^2 of new land since 1855. On the other hand the Aswan Dam cut sediment supply to the Nile by 98%, leading to rapid coastal erosion. Sediment loss on the Mississippi is estimated at about 70% and it too is suffering land loss. A lot of very large cities are sited on river deltas, particularly in Asia, and there is concern about their future if the present rate of seal level rise continues. I imagine there will be a lot of remedial engineering done.

[BTW guess who wrote an undergrad essay on anthropogenic influences on river deltas?]

[multiweb (Marc)]

Originally Posted by AstralTraveller

I suspect that deltas are one of the more dynamic parts of the natural environment. Some of them, at the mouth of rivers with large flow and sediment supply, were naturally quite dynamic but human impacts are making more of them change.

Probably the most dynamic delta is the Huang He in China (the yellow river) which drains the poorly-consolidated loess plateau. It has built 2,200km^2 of new land since 1855. On the other hand the Aswan Dam cut sediment supply to the Nile by 98%, leading to rapid coastal erosion. Sediment loss on the Mississippi is estimated at about 70% and it too is suffering land loss. A lot of very large cities are sited on river deltas, particularly in Asia, and there is concern about their future if the present rate of seal level rise continues. I imagine there will be a lot of remedial engineering done.

[BTW guess who wrote an undergrad essay on anthropogenic influences on river deltas?]

[Sunfish (Ray)]

Thanks Marc , great images and David for the discussion. Very interesting to see an undeveloped delta. Hope it stays that way.

I saw some images in the press of what was thought to be a billion year old delta on Mars.

[Nikolas (Nik)]

Originally Posted by multiweb

Souns like a very dynamic area. I thought deltas were mostly static but you're right, between the tidal sea, rivers and erosion that's a lot interaction. The only sure thing is that it must be a mozzie heaven. Sweden in summer is no better if that's anything to go by. No need for aerogard. A tennis racket is more appropriate.

Definitely Mozzie and Horsefly heaven in those parts. There is a great youtube channel called Survival Russia and the guy who is Danish but moved to Russia discusses this and more about how the native Siberians try and keep them off