Land Drainage
After the second world war intensive development of the contry started; urban planning occupied
approximatelly 1.500 ha of the best and most productive agricultural land (arround cities, villages etc. where urban areas had enlarged). Therefore with smaller and smaller possibilities for food production as far as the area of arable land is concerned (the area of arable land in Slovenia is small), government had decided to start a program of transforming temporary wet meadows into productive fields for intensive crop production.
The analysis in 1970 showed that 150.000 ha of agricultural land in Slovenia was too wet (temporary wet due to heavy soils) for successful crop production.
In that time an intensive land reclamation program started (drainage, land consolidation), financially supported by the government (interventions) and by 1990 72.000 ha of the land had been equipped with drainage systems (by 1990 also urban planning occupied 72.000 ha of the agricultural land). After 1990 intensive drainage works ceased due to increased awareness of environmentalists of the damage drainage caused to wetlands.
Drainage systems in Slovenia consist of:
- open canals as collectors (of 1., 2., 3. order)
- subsurface horizontal drainage pipes (spacing 10-40 m, awerage depth 1,00 m)
- supplemental measures (mole plough or subsoiling done perpendicular to drain pipes);
permeable back-fill (gravel Ø 4-16 mm, 4-32 mm) is in
general used 0,5 m above drainage pipes, mole hole having
contact with gravel. Mole hole is often filled with gravel
(Ø 4-8 mm)
Rivers were trained as well to prevent too freequent floodings. These measures have in some cases substantially changed river ecosystems, resulting in the need to try to restore the habitats to their previous state.
