Summary:

The object of the research was the upper part of the Toczna river valley
(31 + 650 km of the course, surface 865.4 ha), located in the rural Olszanka Commune of Mazovian Voivodeship. Analysis of the water management and land use before and after 30 years from the river regulation were conducted as part of examinations. Archive data, method of putting data from topographical maps and ortofotomap in the ArcGIS program were used in the study. A valorisation of area was conducted with field method (2009-2010). Researches included analysis: scope of river regulation, condition of the irrigation infrastructure, land use, natural resources status and values of the agricultural space in the valley. Maps illustrating the reach and a scope of changes in the valley were drawn up. The river channel change in the upper stretch brought about the land use structure change, the arable land surface and meadow habitats increase. Grasslands are located in the narrow lane offshore channels of the river. According to the typological division they belong to the wet mineral meadow sites, they are characterised by the lowest productivity and the nutritional value. The lowest regulation scope was in the centre stretch of the river. On the considerable part of the valley the channel kept the natural course. Grasslands are still dominating in the structure of the agricultural use, but meadow habitats underwent the transformation. Botanical composition is pointing at a large stake of moorshed sites. The condition of the irrigation system is the best in the lover course. Area is characterised by a great habitat and landscape diversity and a high performance and a nutritional value.