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11
Using SLAMM / Re: MTL parameter for station ...
Last post by Jonathan S. Clough - September 18, 2019, 03:42:20 PM
The DEM must have some vertical datum to which elevations are referenced -- are the elevations in terms of the 1974 datum?

The MTL-NAVD88 parameter is set up such that if you looked at a gauge and there was a referenced MTL height and a referenced NAVD88 height, the value would be the difference of the two numbers referenced.

For example, at this station

MTL is 4.451 and NAVD88 is 3.134 meaning that MTL-NAVD88 would be approximately 1.3 meters.


NAVD88 can be substituted for whatever the datum of the elevation data set is.  So you can convert your datum of elevation to MTL (often ~MSL) and then set the MTL-NAVD88 parameter to zero.

In the case of your figure, if your elevation data are in 1974 datum, MTL-NAVD88 would be 1.46 meters.

Been traveling, sorry about the delay in response -- hope this helps.

12
Using SLAMM / Re: Floating point error
Last post by Jonathan S. Clough - September 18, 2019, 03:31:02 PM
Hi.

The 64-bit version of the software should be able to accommodate nearly any map size -- the limitations are the memory of the machine (and there are also practical limitations in terms of how long it takes to load and run simulations.)   We have found the maximum size that is reasonably practicable to run is approximately 26 GB of memory (~250 million cells) but that obviously requires 32 GB of memory or more. 

Note the memory utilization in GB is given in the SLAMM File setup window and different optimization options are available a the bottom of the screen. 

e.g. "Cells to Track 7,169,539, memory utilization in GB 0.7478"

Are you saying that data can be input at 10m resolution in 6.0.1 but that 6.7 crashes with the same data set?  Have you tried converting the data to binary using the binary button?  This significantly optimizes input/output and may shed light on the problem.  If you cannot solve the problem, you can send me the data files and I can look at it, but I'm afraid I have not been very responsive in terms of loading other people's data lately.  Sorry that the software is not giving you a more helpful error message. 

I hope your problem resolves shortly.
13
Using SLAMM / Re: Floating point error
Last post by andybell - September 18, 2019, 11:41:04 AM
Hi,
A further update.
The data works in version 6.0.1 at the 10m resolution level but runs out of memory at the 2m resolution.

It would nice to run 6.7 version to get the carbon module.

Kind regards
Andy
14
Using SLAMM / Re: Floating point error
Last post by andybell - September 18, 2019, 05:44:06 AM
Hi
Just as an update; I used the sample data and the programme works fine. Therefore it is an issue with my data.
The *.ASC files check OK within SLAMM and they load without issue in QGIS and ArcGIS.

Can anyone advise what are the problems within data that might trigger the "Floating Point" error?

Much obliged
Andy
15
Using SLAMM / Floating point error
Last post by andybell - September 17, 2019, 04:01:03 PM
Hi,
I have just installed SLAMM 6.7 on my laptop (8GB Ramm on windows 10)
I am trying to run a model that I have downscaled from 2m to 10m resolution, but get an error when it reaches 6% in reading the site characteristics. The error reads "Invalid Floating Point Operation". The error comes up when the 6% progress is met

Any clues what might cause this?
Many thanks in advance

Andy


16
Using SLAMM / MTL parameter for station in H...
Last post by felipe.costa@wwf.de - August 14, 2019, 09:04:18 AM
Hello,

I have been struggling to understand how to use the parameter MTL - NAVD88 and would like to check whether my assumptions are correct :)

I believe that since my topgraphic data (DEM) is not projected into any vertical datum, it would be enough to use a factor that would correct the DEM in terms of MTL, right?

If this is right, I would need to factor of correction which accounts for the Tide Mean Level minus the Local Datum level, right?

The station I am considering as input is the Tsim Bei Tsui (ID=1366), which provides the following diagram:
https://www.psmsl.org/data/obtaining/rlr.diagrams/1366.php ; (diagram attached to the message too).
You cannot see attachments on this board.

Is it correct that I should apply the paremeter as" MSL (2001-12) minus Local datum"? In this case, based on the diagram, I would have to use it equals 1.46m.

Can anyone please help me?

Best,
Felipe
17
Using SLAMM / Re: NWI
Last post by Jonathan S. Clough - August 12, 2019, 01:55:53 PM
NWI is a product of considerable technical expertise from US FWS that includes satellite data, infrared photography data, photographic interpretation, and considerable GIS expertise. 

https://www.fws.gov/wetlands/nwi/Overview.html

You do not need an NWI data set to use SLAMM however.  You do need some sort of high-quality vegetation land-cover polygons that can be cross-referenced to the SLAMM categories.

18
Using SLAMM / Re: USE OF SLAMM IN INDIA
Last post by Jonathan S. Clough - August 12, 2019, 01:52:11 PM
Hello:  Thanks for your interest in the model.

1. "ASTER DEM standard data products are produced with 30m postings, and have Z accuracies generally between 10 m and 25 m root mean square error (RMSE)."  I'm afraid that that Z accuracy is not going to be compatible with modeling the effects of 1-2 meters of SLR on marsh systems.  You will need LiDAR or ifSar.  I would say you wouldn't want a vertical RMSE of above 25 cm.

2.  In US applications we get MHHW and MLLW data from NOAA gauges.  You can use whichever type of tide gauge or water level monitoring data that you have available -- long term data are best.

3.  The SLAMM model usually assumes that tidal flats have a lowest elevation at MLLW.  That means that you would need aerial imagery that is tidally coordinated (taken at low tide) 

Best regards -- Jonathan
19
Using SLAMM / USE OF SLAMM IN INDIA
Last post by ommg - July 25, 2019, 10:47:09 PM
Sir I am completely new to work on slamm model.so I have the following questions

1.Is Aster DEM is relevant instead of Lidar data.
2.Where to get the MHHW,MLLW DATA?
3.I am working on tidal flat.so how to define the polygon class for the tidal flat?

looking forward for first reply as I am eager to work on this model.
Thank you. :)
20
Using SLAMM / Re: NWI
Last post by rezaul - July 12, 2019, 04:37:17 AM
i got 2 queries,
1. how to produce NWI data ( i was looking for a more clear answer as i am not that expert in GIS)?
2. If I use ASTER GDEM data other than LiDAR, will I face any problem with my result?
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