SWR Surface Water Routing Process

[Markus]

Hi to All,

 

is there someone with experience regarding the SWR process?

My first steps with SWR surface water routing process and MODFLOW 2005 show some  unclarities:

1.  If a system of reach groups (IROUTETYPE=1, IGEOTYPE=5) - i.e. lake/wetland areas - is connected to an upstream contributing linear reach (IROUTETYPE=3, IGEOTYPE=3) - i.e.  a channel - and connected in between the lakes as well by channels,  MODFLOW returns after the first stress period: "....matrix is severely non-diagonally dominant...."
2. If a system of reach groups (IROUTETYPE=1, IGEOTYPE=5) - i.e. lake/wetland areas - is not connected to any other linear reach ( IROUTETYPE=3, IGEOTYPE=3), MODFLOW continues the calculation.
3. If  a single reach group (IROUTETYPE=1, IGEOTYPE=5) - a lake/wetland area - is connected only to a downstream channel (IROUTETYPE=3, IGEOTYPE=3), MMODFLOW continues the calculation.

Something seems to go wrong in that case that a consecutive series of lakes is getting water from an upstream channel and is interconnected among each other lakes as well by channels with a final outlet from the most downstream lake. (Note: the model is located in impoldered area within a tidal setting where the flow direction within the surface water system sometimes is reverse depending on the season's conditions and water managemant aspects, therefore the intention to use SWR).

Thank you for your contributios

Regards

Markus

[stephan....@gmail.com]

Regarding the problem with the severly non-diagonally maxtrix: Have you tried changing the solver settings?

Maybe the problem lies within your conceptual approach: Please note the flow direction of the SWR-reaches are set by the direction of your polyline. The SWR CAN NOT calculate respectivily change the flow direction!

[Markus]

Hi Stephan,

thank you for your comments!

• yes,  a very good advice, meanwhile I checked other solvers. It's getting better :-)
• this is a citation from the documentation (TM6-A40): ".....the SWR1 Process can account for backwater (tailwater) effects, bidirectional surface-water flow, and management of surface water using control structures."

Rgds Markus

[Randall Hanson]

SWR1 also is in the newest version of Modflow called Modflow-OWHM (version 2) and has been successfully used in places like Buenos Aires, Argentina. So you may want to use this version as it has more options, features and more solver options too.

Cheers,

Randy Hanson

One-Water Hydrologic

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[Markus]

Hi Randall,

thank you for this hint. I think I should have a close look on OWHM. I wonder how much effort needs to be involved to switch from a 2005 model to a OWHM model.

Rgds

Markus

[Randall Hanson]

Markus very little effort is required to switch to MF-OWHM and it has many more features and options. Again it was used to assess runoff in Buenos Aires and is included in the example model of our version 1 release (Hanson et al, 2014) and version 2 release (Boyce et al, 2020).

Cheers 

Randy Hanson

One-Water Hydrologic

http://www.One-WaterHydrologic.com/

Sent from my iPhone

On May 19, 2025, at 7:31 AM, Markus <m.h...@geobit-aachen.de> wrote:



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