EN 1991-1-4 Table 4.1 - Terrain categories and terrain parameters
Terrain cathegory	0	I	II	III	IV
z0 (m)	0.003	0.01	0.05	0.3	1
zmin (m)	1	1	2	5	10
Zone 0	Sea or coastal area exposed to the open sea
Zone I	Lakes or flat and horizontal area with negligible vegetation and without obstacles
Zone II	Area with low vegetation such as grass and isolated obstacles (trees, buildings) with separations of at least 20 obstacle heights
Zone III	Area with regular cover of vegetation or buildings or with isolated obstacles with separations of maximum 20 obstacle heights (such as villages, suburban terrain, permanent forest)
Zone IV	Area in which at least 15% of the surface is covered with buildings and their average height exceeds 15m