>Jan writes:
>> "Indeed, between WWI and WWII the Zuiderzee was closed off from the
>> North
>> Sea bya dike. Then four polders were made in the Zuiderzee, which was
>> originally an arm of the North Sea, created in the Middle Ages by the
>> St.Elisabeth flood. Part of the water of the Rhine mptied in the
>> Zuiderzee.
>> I do not know, how that fact influence the siltiness of the soil, but
from
>> what I understand of the rivers in Sumer, they brought water from the
>> mountains too. If that is so, then maybe the fact that the first polder
>> was
>> prime agricultural land after 10 to 20 years, indicates that the salt may
>> not take 200 years to leach out. After WWII three more polders were
>> brought
>> in to production (one was poldered in before the war.) To my knowledge
>> the
>> silt is gone now."
>>
> It is my recollection that the original Zuider Zee was supplied by
>water from the Rhine via some smaller streams (Vecht? and the river that
>flows past Deventer and Zwolle)
The name of that river is IJsel, the Vecht is a smaller river in East
Overijsel, but emptied in the Zuiderzee too.
>After the dike was built at the mouth of
>the Zuider Zee, that body of water would have become progressively less
>saline and more brackish. This would be somewhat different than along the
>coast where there is a constant supply of seawater. Further south the
>seawater is more saline and around Iraq I would therefore expect the silt
to
>be more saline initially.
The polders in the Lauwerszee (off the Waddenzee, between the provinces of
Groningen and Friesland) would be a better example, though the sea was
closed off there too, and the water of the Hunze river emptied there via a
canal. The Hunze is, however, a rather small stream.
Jan de Koning
Willowdale, Ont.