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All Topics | Topic "Some questions about the basin and catchment"
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Mr. Zhaoyi Zhang

Subject: Some questions about the basin and catchment   
Posted: 3/8/2021 Viewed: 4901 times
To whom it may concern,

I'm using catchment mode to build two basins(two main and independent rivers). However, WEAP model concerns that one river(A) is the tributary for the other(B), and make the inflow from A to B, and A has it's own marine outfall in reality. So how can I solve this problem?

Another question is, I want to use other DEM to make the basin(ASTAR GDEM, etc.), but I haven't found the selection(whether the "Date source" in the OPTIONS?), can WEAP changes the source of DEM? And which DEM used by WEAP now for the basin & catchment's building?

Thanks in advance:)
Mr. Jack Sieber

Subject: Re: Some questions about the basin and catchment   
Posted: 3/8/2021 Viewed: 4894 times
Always create the basin with the main river before the basins with tributaries. The first basin you create will be the one that flows to the ocean. Therefore, you need to delete the basins and draw the one with river A first.

You can change the land use data source and the climate data source but not the DEM data source. It comes from HydroSHEDS. See the help for more information.


Mr. Zhaoyi Zhang

Subject: Re: Some questions about the basin and catchment   
Posted: 3/8/2021 Viewed: 4881 times
Thanks for replied, Mr. Sieber. I try to create the river A first, however, the model shows me the basin of B, the same like the problem I faced at first.

Maybe I didn't express clearly in the topic first(due to my poor English). My study area is coastal delta, which is the end of several river, such as River A, B, etc. River A and B are close in the delta(sincerely, very close in somewhere, but not cocurrent flow), and importantly, A and B will flow to the sea independent(two marine outfall in result).

Whatever the sequence for the basin built, the basin B will contains basin A. The model doesn't show the full reality basin for River A: the marine outfall is not in range, basin A is ended in the "inflow point" from A to B. I think the River A is considered to be a tributary for River B by model or data for some reasons(despite this consideration is wrong).

I tried to move the pour point to divide A and B, but failed. And as I mention, the imperfection of basin A in WEAP.

Thanks in advance:)

Mr. Jack Sieber

Subject: Re: Some questions about the basin and catchment   
Posted: 3/9/2021 Viewed: 4878 times
Unfortunately, in a situation such as a coastal plain, where the variation in elevation is small, the digital elevation data (DEM) that WEAP uses is not accurate enough to distinguish the flow of every river. In future versions of WEAP we hope to allow alternative DEM data to be used, but for now you will not be able to separate these two basins.

Ms. Anne Hereford

Subject: Re: Some questions about the basin and catchment   
Posted: 3/12/2021 Viewed: 4867 times
If you have your own DEM, you can always use it to draw your catchments in GIS and then manually build your model using Area, Land Use, and other data derived from GIS. As you might guess, this is more labor-intensive than automatic catchment delineation, but it allows you to use a more detailed and/or accurate DEM if you have access to one.

For general guidance about building a model manually, take a look at the WEAP Tutorial document and videos.

Topic "Some questions about the basin and catchment"