Calculating the difference between time steps

[Bruce K]

I have some .dat files from a TUFLOW model- this records depth in a time series. We are hoping to process the data so that we can record 2 things

- the time a cell gets wet (ie increases from 0)

- the maximum rate of rise in depth ( ie the maximum difference between consecutive time steps) and the time this occurs.

As a new user, any help in the syntax to use in Data Calculator would be greatly appreciated, or any pointers to appropriate tutorials.

Many thanks

Bruce

[Rusty Jones]

Hi Bruce,

Unfortunately, the data calculator was not setup with these needs in mind. It is generally used to compute derived values such as Froude number or to compare separate datasets. You could compute the rate of rise of depth between timesteps but you would have to change the data expression each time. Something like d:2-d:1 (where the last number is the timestep index). Then you could do a maximum of all of these datasets. If you have lots of timesteps this would be somewhat painful.

I'm not sure how you would get the time a cell gets wet. I can't think of a way to do this in SMS. Bill Syme has created a useful utility named dat_to_dat.exe, but I don't think it contains this functionality either.

http://www.tuflow.com/Downloads_Utilities.htm

I wish I had a good solution for you, but I can't think of one. You could try the TUFLOW forum and see if anyone else has ideas on how this can be done.

By the way, what kind of applications are you doing that benefits from this data?

I have some .dat files from a TUFLOW model- this records depth in a time series. We are hoping to process the data so that we can record 2 things

- the time a cell gets wet (ie increases from 0)

- the maximum rate of rise in depth ( ie the maximum difference between consecutive time steps) and the time this occurs.

As a new user, any help in the syntax to use in Data Calculator would be greatly appreciated, or any pointers to appropriate tutorials.

Many thanks

Bruce

[Bruce K]

Hi Rusty,

Thanks- I thought as much but thought I would ask anyway. We use Bill's- dat to dat converter, but your're right, it doesn't quite do this.

We're using depth grids from a Tu Flow model, so ideally we would able to find out the time that a certain area is actually flooded during a event. This could help with emergency planning response times. The second stage would be to identify the time of the greatest increase in depth per area- ie one of the elements that help use to identify hazard to an area.

Many thanks

Bruce