Import an empty 2d_mat layer in the GIS and save in the “model\mi” folder as, for example, “2d_mat_my_model”. The layer has no geographic objects and one attribute named Material that must be an integer value.
Add the layer to your GIS work environment and make it editable. Digitise regions of different material types, noting that each material is assigned a Manning’s n value. For example: river in-bank; river banks; pasture; roads; lakes; sugar cane; etc. The most common or most difficult to digitise material may be omitted and set as the default material. The different materials to be digitised should be determined in advance of the digitising.
Use Read MI Mat in the .tgc file to read the 2d_mat layer(s) developed as follows.
