Small retention is the ability to store water in small reservoirs, both natural and manmade. It can also take the form of damming water in the beds of minor rivers, streams, in canals and ditches. These all have the single purpose of storing water and making its rapid surface drainage impossible.

Projects of a European dimension

State Forests commenced the construction of new water reservoirs and the restoration of old ones in the mid-1990s within the small retention programme to sustain forests and their continuity and to be able to make full use of the functions they can perform. In less than 10- years several hundred new small water storage reservoirs were constructed with a water plane exceeding 900 hectares.. The builders of many of these were awarded the title of Polish Ecology Leader due to the pro-ecology character of these investments.
Two years ago a decision was taken to merge the dispersed operations of forestry commissions and since last year, within the EU Infrastructure and Environment Operational Programme, preparations are under way to implement two comprehensive projects concerning small retention in forests.

In depressions ….

“Small water retention in depressions” – such is the name of the project “Increasing possibility of water retention and counteracting flooding and drought in forest ecosystems in low-lying country”. Its principal purpose is to halt or slow the surface outflow of water within small catchment areas. Small storage reservoirs of up to 10 hectares are to serve that purpose, also water gates, river bars, weirs, dykes, culverts and ditches, both modernised items as well as newly constructed. The project also envisages the restoration of drained marshes and, wherever possible, the recreation of natural river meanderings. The volume of water stored in such a manner will amount to around 45 mln cubic metres while the total water plane of the more than 4000 storage facilities – to around 1000 hectares.

Specialists are of the opinion that implementing this project will improve the water balance of small catchment areas, minimises the effects of drought in forests and counteract flooding. In other words by raising the water table and storing it in the forest, the health of trees growing in the vicinity of the reservoir should improve. That is particularly true of deciduous trees which have recently been experiencing regression due to the lack of sufficient water. But that is not everything. Experts claim that the overall effect of a large number of small storage objects will also be sensed in outside a given region, especially as regards restricting the effects of drought and flooding in afforested land as well as reducing flooding on rivers below. Due to the scale of the project, it could well become Europe’s first small water storage venture undertaken on such a scale and with such momentum.

…. And in the mountains
The second project elaborated by State Forests concerns water erosion in the highlands. Most Polish people remember the flood of July 1997 in the Vistula and Odra Rivers drainage areas which caused damage amounting to PLN 12 bln. A project “Counteracting water erosion in mountainous land and maintaining mountain streams in good state” was elaborated specifically to counteract such extreme phenomena. The project envisages operations being undertaken to increase the retention potential of such areas, protecting slopes against water erosion or restricting side and bed erosion in streams. The General Management of State Forests is the beneficiary of both projects. 190 forestry commissions are participating in the first concerning small-scale water storage in depressions, the expected cost of investments being EUR 40 mln. 35 Sudety and Carpathian forestry commissions are taking part in the project concerning erosion in mountainous areas, the estimated total cost of that venture being EUR 30 mln. Both projects are to be implemented between 2008 and 2013.