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Next message Tom Coulthard (Tom)  posted on Friday, March 31, 2006 - 04:24 pm
QUestion from Jiali:

professor coulthar:
i have a question for you about the CAESAR MODEL. how the rainfll date file and the grain date file was made? your example online is in the form of txt.And there are so much mumbers. i don't know how to make it.
If i have to get the waterdepth file ,the grain date file and the bedrock date file by reading the remote sensing picture.
is there any parameter for me to change when i use the model? i think some parameter should be changed to adapt to different drainage area. am i right? if so, which one can i change?
thank you for your reply!
jiali
CHINA.
Next message Tom Coulthard (Tom)  posted on Friday, March 31, 2006 - 04:24 pm
Hello Jiali,


professor coulthar:
i have a question for you about the CAESAR MODEL. how the rainfll date file and the grain date file was made? your example online is in the form of txt.And there are so much mumbers. i don't know how to make it.

Rainfall data is from a genuine rain gauge, and it is hourly, with each line corresponding to an hours worth of data in the format:

0
0
0
0.2
0.5
0.7
1.2
0
0

Etc... The units are in mm per hour.


If i have to get the waterdepth file ,the grain date file and the bedrock date file by reading the remote sensing picture.

The grain data file is very hard to make. What I do is run the model for a spin up period - where the model assumes there is the same grainsize distribution everywhere. During this period the fines are removed from the system, and the model develops its own grainsize distribution. This can take a while (10 or 2o years of simulation) and the best way to check when it is done is to feed in the same rainfall data (say a years worth) repeated many times, and plot the total sediment discharge.. Initially this will be very high, as the fines are removed from the catchment, but after a while it will stabilise - this is when you can start the run proper. There is no need for a waterdepth file to start with - and the bedrock file can be set at 2m below the regular dem - it just stops the channel incising down too much in some places. If there are no bedrock controls on incison in your river system then you do not need one.

is there any parameter for me to change when i use the model? i think some parameter should be changed to adapt to different drainage area. am i right? if so, which one can i change?

I'm not sure that I understand your question, but CAESAR should automatically read in the size of the catchment that is being modelled.

I hope all this helps,
Tom
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