Changes in the Input File Regarding Point sources for River Forcing

[Sankar]

Hello everyone. I want to give river in my domain using LuvSrc = T option and the LtracerSrc = T for both salinity and temperature. For checking, I have used the Matlab function map_rivers.m. The direction of the rivers is attached here. I m literally confused about the direction and the position of the point as I am not getting any influence of these rivers in the salinity field. Not to mention, these are the rivers in the Bay of Bengal with very large discharge values. It would be very beneficial if someone could help me with this issue, whether the direction and the grid point are correct. Do I have to change any other option in the .in file for this as well? Thank you in advance.

[wilkin]

You may be off by one in your river_Xposition etc if you have not adjusted for FORTRAN indexing as opposed to Matlab. This is explained in WikiROMS https://www.myroms.org/wiki/River_Runof ... _Eposition.

roms_plot_river_source_locations.m from my ROMS tools at https://github.com/johnwilkin/roms_wilkin will plot locations (with symbols to indicate direction) directly from your rivers file and a grid structure created by roms_get_grid.m in the same repo.

[zduvims]

Hello everyone. I want to give river in my domain using LuvSrc = T option and the LtracerSrc = T for both salinity and temperature. For checking, I have used the Matlab function map_rivers.m. The direction of the rivers is attached here. I m literally confused about the direction and the position of the point as I am not getting any influence of these rivers in the salinity field. Not to mention, these are the rivers in the Bay of Bengal with very large discharge values. It would be very beneficial if someone could help me with this issue, whether the direction and the grid point are correct. Do I have to change any other option in the .in file for this as well? Thank you in advance.

I think the map_rivers may not be correct for the j-direction river. When I used map_rivers.m, it showed me I have rivers from north to south, but actually it was from south to north. You can make rivers the only input forcing, and check the velocity and salinity fields.

To my understanding, the river_transport is positive when the flow is through the left-hand u (or v) face to the right-hand u (or v) face. How to determine which face is on the left-hand side? I am not 100% on this, but I think the correct left-hand side of the v-face is when you are facing the positive I-direction. So, if your positive I-direction is from west to east, the river_transport would be positive if the flow is from north to south. Correct me if I was wrong

[wilkin]

Look at the figure here:
https://www.myroms.org/wiki/River_Runof ... _Eposition

It is for you, as user, to decide whether your source points falls on a coastline with land on the left or right. If it is Case A (in the figure), then river_direction = 0, river_Xposition = i and river_transport is positive. If it is Case B, then river_Xposition = i+1 and river_transport is negative. Similarly for v direction sources (river_direction = 1) you have to be clear, looking at your land/sea mask, whether you mean flow to be in the positive or negative "j" direction and set the sign of river_transport accordingly.

This almost always needs some user interaction to get correct. I don't know the map_rivers.m function you mention so can't comment on what it is doing.

[Sankar]

Thanks, Prof Wilkin and Zhiyun, for your reply. I have checked my river points with the roms_plot_river_source_locations.m, and it shows the desirable points now. Previously, I didn't incorporate case (b) from this figure https://www.myroms.org/wiki/River_Runof ... _Eposition.

I think the map_rivers may not be correct for the j-direction river. When I used map_rivers.m, it showed me I have rivers from north to south, but actually, it was from south to north.

In my case, this function shows the river direction and the points properly.
Now all my river points are at the interface and correctly showing the river direction in the Matlab plots. But still, I have a doubt. Do I have to change the i,j points according to the Fortran numbering, or the Matlab codes ( roms_plot_river_source_locations.m or map_rivers.m) have been adjusted to the Fortran numbering itself and then it is showing the river points in the plot? I am a bit confused here.