MUD, SAND and BEDLOAD

[rsignell]

In releases of ROMS prior to R224 (released Aug 19, 2008), if you specified your sediment as MUD or SAND, it didn't really matter, as they were treated identically.

With versions R224 and higher, MUD and SAND are treated differently. BEDLOAD for example, only works with SAND.

I found this out the hard way. I ran the TEST_HEAD test case supplied in the latest version of ROMS (rev 271), as this is the only test case where BEDLOAD (#define BEDLOAD_MPM) is turned on. But when I checked bedload_Umud_01 in ocean_his.nc, all the values were zero.

After struggling a bit, John Warner pointed out that that the bedload loop in the new sed_bedload.F routine now runs from

Code: Select all

    DO ised=NCS+1,NST

and since NCS=1, NNS=0 was set in the ocean_test_head.in file, NST was equal to 1 and therefore bedload was not getting calculated.

I thus needed to modify the ocean_test_head.in file to set NCS=0, NNS=1, modify the sediment_test_head.in file to specify parameters for SAND instead of MUD, and also change the variable names from MUDFRAC_01 to SANDFRAC_01, MUD_01 to SAND_01, etc in the initialization NetCDF file test_head_ini.nc. Once I made these changes, the TEST_HEAD test case run with the R71 code (current trunk code) produced non-zero bedload values equivalent to versions prior to R224.

These modified input files for TEST_HEAD are at: http://coast-enviro.er.usgs.gov/models/ ... t_head.zip
if anyone is interested.