[GRASS-user] multiflow direction models

GRASS GRASS user
1

Good morning,

I am wondering if anyone knows whether David Tarboton's D-infinity
multiflow direction algorithms have been integrated into a GRASS module.

Thank you,

Kessie.

--
Ksenia E. Konwicki, RPF
Ecologist

Timberline Forest Inventory Consultants
1579 9th Avenue
Prince George, BC V2L 3R8
P (250)562-2628
F (250)562-6942
E kes@timberline.ca

2

On Mon, 15 May 2006 11:34:04 -0700
Ksenia Konwicki <kes@timberline.ca> wrote:

Good morning,

I am wondering if anyone knows whether David Tarboton's D-infinity
multiflow direction algorithms have been integrated into a GRASS module.

Thank you,

Kessie.

See

http://www.grass.itc.it/grass60/manuals/html60_user/r.flow.html

T
--
Trevor Wiens
twiens@interbaun.com

The significant problems that we face cannot be solved at the same
level of thinking we were at when we created them.
(Albert Einstein)

3

Kessie,

Might check on some past GRASS-user messages on this thread:

http://grass.itc.it/pipermail/grassuser/2006-February/032744.html

Perhaps it would be a good time to create a page on this...

Dylan

On Monday 15 May 2006 11:34, Ksenia Konwicki wrote:

Good morning,

I am wondering if anyone knows whether David Tarboton's D-infinity
multiflow direction algorithms have been integrated into a GRASS module.

Thank you,

Kessie.

--
Ksenia E. Konwicki, RPF
Ecologist

Timberline Forest Inventory Consultants
1579 9th Avenue
Prince George, BC V2L 3R8
P (250)562-2628
F (250)562-6942
E kes@timberline.ca

_______________________________________________
grassuser mailing list
grassuser@grass.itc.it
http://grass.itc.it/mailman/listinfo/grassuser

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341

4

Kessie,

Ah. Well this might be a good time to ask the GRASS developers to clarify. You
might also check out the docs behind r.terraflow .

cheers,

Dylan

On Monday 15 May 2006 13:51, Ksenia Konwicki wrote:

Thanks Dylan.

I followed this string fairly closely when it was active. I have
investigated r.flow and r.flowmd.

Question though... I am a little confused by the r.flow documentation. It
states that it used the D-inf logarithm to calculate flow direction,
however flow accumulation uses a single flow direction logarithm. The
r.flowmd module appears also offer D-inf flow direction however it seems to
only offer the Desmet & Govers multiflow contributing area calculations for
flow
accumulation.

Our research favours Tarboton's algorithms. We would like to use GRASS for
the computations however we will have to find a programmer or another Open
Source option if it is not available.

Thank you,

Kessie.

Dylan Beaudette wrote:
> Kessie,
>
> Might check on some past GRASS-user messages on this thread:
>
> http://grass.itc.it/pipermail/grassuser/2006-February/032744.html
>
> Perhaps it would be a good time to create a page on this...
>
> Dylan
>
> On Monday 15 May 2006 11:34, Ksenia Konwicki wrote:
> > Good morning,
> >
> > I am wondering if anyone knows whether David Tarboton's D-infinity
> > multiflow direction algorithms have been integrated into a GRASS
> > module.
> >
> > Thank you,
> >
> > Kessie.
> >
> > --
> > Ksenia E. Konwicki, RPF
> > Ecologist
> >
> > Timberline Forest Inventory Consultants
> > 1579 9th Avenue
> > Prince George, BC V2L 3R8
> > P (250)562-2628
> > F (250)562-6942
> > E kes@timberline.ca
> >
> >
> > _______________________________________________
> > grassuser mailing list
> > grassuser@grass.itc.it
> > http://grass.itc.it/mailman/listinfo/grassuser
>
> --
> Dylan Beaudette
> Soils and Biogeochemistry Graduate Group
> University of California at Davis
> 530.754.7341

--
Ksenia E. Konwicki, RPF
Ecologist

Timberline Forest Inventory Consultants
1579 9th Avenue
Prince George, BC V2L 3R8
P (250)562-2628
F (250)562-6942
E kes@timberline.ca

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341

5

Jus a short explanation - people often mix 2 things - flow direction and flow accumulation.

You can have the following flow/gradient direction:
D-4 (direction is discretized with 90 deg step), D-8 (discretized with 45 degree step), D-inf (discretization is
defined by FP precision)

The flow accumulation can be computed as
SFD (single flow direction - all water flow into single lowest cell),
MFD (multiple flow direction - water is distributed into multiple lower cells - different rules can be set),
  full 2D (bivariate routing according to continuity equation).

You can combine these in different ways, none of the methods in GRASS is exactly the same as Tarboton's.

Helena

On May 15, 2006, at 5:15 PM, Dylan Beaudette wrote:

Kessie,

Ah. Well this might be a good time to ask the GRASS developers to clarify. You
might also check out the docs behind r.terraflow .

cheers,

Dylan

On Monday 15 May 2006 13:51, Ksenia Konwicki wrote:

Thanks Dylan.

I followed this string fairly closely when it was active. I have
investigated r.flow and r.flowmd.

Question though... I am a little confused by the r.flow documentation. It
states that it used the D-inf logarithm to calculate flow direction,
however flow accumulation uses a single flow direction logarithm. The
r.flowmd module appears also offer D-inf flow direction however it seems to
only offer the Desmet & Govers multiflow contributing area calculations for
flow
accumulation.

Our research favours Tarboton's algorithms. We would like to use GRASS for
the computations however we will have to find a programmer or another Open
Source option if it is not available.

Thank you,

Kessie.

Dylan Beaudette wrote:

Kessie,

Might check on some past GRASS-user messages on this thread:

http://grass.itc.it/pipermail/grassuser/2006-February/032744.html

Perhaps it would be a good time to create a page on this...

Dylan

On Monday 15 May 2006 11:34, Ksenia Konwicki wrote:

Good morning,

I am wondering if anyone knows whether David Tarboton's D-infinity
multiflow direction algorithms have been integrated into a GRASS
module.

Thank you,

Kessie.

--
Ksenia E. Konwicki, RPF
Ecologist

Timberline Forest Inventory Consultants
1579 9th Avenue
Prince George, BC V2L 3R8
P (250)562-2628
F (250)562-6942
E kes@timberline.ca

_______________________________________________
grassuser mailing list
grassuser@grass.itc.it
http://grass.itc.it/mailman/listinfo/grassuser

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341

--
Ksenia E. Konwicki, RPF
Ecologist

Timberline Forest Inventory Consultants
1579 9th Avenue
Prince George, BC V2L 3R8
P (250)562-2628
F (250)562-6942
E kes@timberline.ca

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341

6

Thanks for the description Helena.

All this talk about Tarboton, reminded me of a paper on his website that goes
into a bit of the background on other problematic terminology. In addition,
there is an interesting overview of stream network extraction via detection
of curvatures in a DEM:

http://www.engineering.usu.edu/dtarb/asce2001.pdf

Cheers,

Dylan

On Monday 15 May 2006 14:41, Helena Mitasova wrote:

Jus a short explanation - people often mix 2 things - flow direction
and flow accumulation.

You can have the following flow/gradient direction:
D-4 (direction is discretized with 90 deg step), D-8 (discretized
with 45 degree step), D-inf (discretization is
defined by FP precision)

The flow accumulation can be computed as
SFD (single flow direction - all water flow into single lowest cell),
MFD (multiple flow direction - water is distributed into multiple
lower cells - different rules can be set),
  full 2D (bivariate routing according to continuity equation).

You can combine these in different ways, none of the methods in GRASS
is exactly the same as Tarboton's.

Helena

On May 15, 2006, at 5:15 PM, Dylan Beaudette wrote:
> Kessie,
>
> Ah. Well this might be a good time to ask the GRASS developers to
> clarify. You
> might also check out the docs behind r.terraflow .
>
> cheers,
>
> Dylan
>
> On Monday 15 May 2006 13:51, Ksenia Konwicki wrote:
>> Thanks Dylan.
>>
>> I followed this string fairly closely when it was active. I have
>> investigated r.flow and r.flowmd.
>>
>> Question though... I am a little confused by the r.flow
>> documentation. It
>> states that it used the D-inf logarithm to calculate flow direction,
>> however flow accumulation uses a single flow direction logarithm. The
>> r.flowmd module appears also offer D-inf flow direction however it
>> seems to
>> only offer the Desmet & Govers multiflow contributing area
>> calculations for
>> flow
>> accumulation.
>>
>> Our research favours Tarboton's algorithms. We would like to use
>> GRASS for
>> the computations however we will have to find a programmer or
>> another Open
>> Source option if it is not available.
>>
>> Thank you,
>>
>> Kessie.
>>
>> Dylan Beaudette wrote:
>>> Kessie,
>>>
>>> Might check on some past GRASS-user messages on this thread:
>>>
>>> http://grass.itc.it/pipermail/grassuser/2006-February/032744.html
>>>
>>> Perhaps it would be a good time to create a page on this...
>>>
>>> Dylan
>>>
>>> On Monday 15 May 2006 11:34, Ksenia Konwicki wrote:
>>>> Good morning,
>>>>
>>>> I am wondering if anyone knows whether David Tarboton's D-infinity
>>>> multiflow direction algorithms have been integrated into a GRASS
>>>> module.
>>>>
>>>> Thank you,
>>>>
>>>> Kessie.
>>>>
>>>> --
>>>> Ksenia E. Konwicki, RPF
>>>> Ecologist
>>>>
>>>> Timberline Forest Inventory Consultants
>>>> 1579 9th Avenue
>>>> Prince George, BC V2L 3R8
>>>> P (250)562-2628
>>>> F (250)562-6942
>>>> E kes@timberline.ca
>>>>
>>>>
>>>> _______________________________________________
>>>> grassuser mailing list
>>>> grassuser@grass.itc.it
>>>> http://grass.itc.it/mailman/listinfo/grassuser
>>>
>>> --
>>> Dylan Beaudette
>>> Soils and Biogeochemistry Graduate Group
>>> University of California at Davis
>>> 530.754.7341
>>
>> --
>> Ksenia E. Konwicki, RPF
>> Ecologist
>>
>> Timberline Forest Inventory Consultants
>> 1579 9th Avenue
>> Prince George, BC V2L 3R8
>> P (250)562-2628
>> F (250)562-6942
>> E kes@timberline.ca
>
> --
> Dylan Beaudette
> Soils and Biogeochemistry Graduate Group
> University of California at Davis
> 530.754.7341

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341