Incorporating a Centrally Located Terminal Lake in a Watershed

[Aarushi Jha]

Hello fellow SWAT users,

I am working on modeling the Salton Sea watershed in Southern California. The watershed consists of the Salton Sea (Sea), which is a terminal lake located centrally in the watershed. The watershed does not have one specific outlet as all the streams, irrigation discharge etc flow into the Salton Sea. The Sea is pictured in red below, and the study watershed is also outlined in red. As you can see the default TAUDEM delineated subbasins overlap the Sea. 

Adding outlet points at the intersection of the lake and stream network seems to be a method that has worked for others. To incorporate the Salton Sea into the subbasin delineations, I manually added outlets where the stream network discharged into the SS using the 'draw inlets/outlets' option in QSWAT. However, the model only delineated the subbasins on the north end. Is this because it is taking the southern outlet as the final outlet of the watershed? 

I tried adding discharge points only at the south end to see whether the model would delineate the southern subbasins but found that it still delineated the northern subbasins and is taking the southern outlets as the final watershed outlet – perhaps because of a north to south gradient?

 

I would really appreciate any input on how others have incorporated lakes into their subbasins and if any have worked with a terminal lake and watershed without a "pour point" outlet.  

Regards,

Aarushi 

[Awel Seid]

Hi Mr Aarushi.

I have the same problem as you had. I have been stuck there for weeks while trying to delineate the Lake Hawassa watershed in Ethiopia. I tried to look around for alternative solutions, but not succeeded. 

Since you had faced the problem long ago (in 2019), I assume you have already resolved it by now. Can you please share me how you go about it?

Thank you in advance.