[GRASS-user] New module for lake filling - r.lake

[Māris Nartišs]

Re-posting, as previous mail was larger than lists accept.

Hello all GRASSers.

GRASS CVS contains new module r.lake. This module can be used to create lake 
maps if only place and lake level is known. To use this module You need 
terrain raster map (DEM), water level for lake in same units as DEM values 
and coordinates for any point in lake.

Module uses 3x3 sliding window to fill whole area connected to seed point (can 
be coordinate pair or already existing raster map) and having height values 
below water level. Output map will have lake depth in DEM units. More 
information about module is in help page. 

I use this module for palaeolake reconstructions based on single shore line 
measurement. It also can be usefull for reservoir planing, creating maps with 
scenarios for lake level changes etc. Unfortunately mailing lists does not 
accept attachments larger than 100kb - no sample images with r.lake in 
action.

Currently this module has some limitations and I ask for help to other GRASS 
developers to help me to fix them.
Most important - module is NOT large file safe.
Lake volume calculations work only if DEM is in meters. 
G_area_of_cell_at_row() always returns cell area in square meters, but I 
could not figure out how to get information about DEM units. Thus if both are 
in meters, volume is correct, else not ...

Thanks to all who helped me to code this module.

Any comments, ideas, enhancements - always welcome.

Maris Nartiss.