In comparison to other European countries Poland has the least favourable water system. Water deficit is strongly felt in the central belt of the Polish lowland, from Wielkopolska through Kujawy, Mazowsze, Podlasie, and Lubelszczyzna as far as the eastern border of the country. According to statistical data from the end of the 1970s, acreage of overdried agricultural land measured about 4 million ha. The majority of this land has low woodiness indicators. The poor condition of the land is caused by extensive deforestation done in the past as well as the mistakes made in water resources management. Among these errors were the excessive straightening and deepening of the river channels and the drainage of marshes, moors and periodically wet farmlands. During the process of reclamation drainage systems were introduced. However the one-sided efforts to drain without taking care to store the periodical excess water in retention reservoirs led to water reserves. These reserves could be useful in cases of drought. The lack of reserves is especially dangerous for light soils. As a result of soil overdrying and the accelerated rate of surface runoff, the level of ground water has dropped. Areas which had a large water storage capacit, for example moors, marshes, meadows and pastures were cultivated. Accelerated decomposition and mineralization of organic material contained in these lands caused a further reduction in their water storage capacity. It is well known that the water retention capacity of inanimate organic substances can be up to ten times higher than the retention capacity of mineral soils.

The protection of water resources must consist of storing as much water as possible from the spring thaw and from the periods of intensive precipitation. This can be done by reducing the unproductive runoff (MAPS illustrating the expected increase in water runoff, resulting from global climate change). Forests and field tree plantings reduce snow melt and slow down surface runoff. Compared to woodless terrain, an additional 20 to 30 mm of water may soaks into the soil. The water retained that way can serve as a reserve for summer droughts. Increasing the share of forest and tree plantings in the landscape, protection of marshes, meadows and rushes, preservation of streams and reservoirs, and using natural depressions for periodical retention of surplus of drainage waters, all of these measures reduce and slow down water runoff into catchments and allow for rational utilization of water resources according to the needs of agriculture. From the above it follows that the condition of the water system can be significantly improved by conscious and proper shaping of the agricultural landscape.In Poland this is especially true in the case of the central lowlands which have a poorly developed water network and light and easily permeated soils. In this area exists the greatest need for afforestation and tree planting.

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