2949775677

75

The influence of anthropopressure..

In the years 1810-1812 the first thorough maintenance work along the canals, entailing the removal of aggradate muds, was carried out. With the use of technical means available at that time maintenance of canals was very difficult due to the limited access to the areas as well as the incompleteness of maps and drawings.

The partial drainage of the upper Obra valley, carried out in 1820-1823, enabled work to commence on new land surveys, and in conseąuence further development of the basie land melioration system. Major land melioration work was undertaken in 1825. This involved extending the Kościan Canal from Kościan to Krzywiń and building a canal starting in Wonieść lakę. In 1830 the canal between Krzywiń and Goworek was completed, and later, in the years 1830—1831, the Central Canal running through the middle of the Obra river Great Ash-Alder Forest was dug.

The main network of ditches was completed and the correction of existing canals was carried out following the institution of Towarzystwo Melioracji Obrzańskich (the Obra River Land Melioration Society) in 1842. The statutes of the Society were signed by the Prussian king Frederick William on 16th August in his Sanssouci residence. In the following years further water companies were established. Using government loans they drained particular wetlands or lowered the water level in lakes in order to reclaim new lands. The companies were formed in order to lower the water level in: Slesińskie Lakę near Bydgoszcz (1844), and the Powidzkie, Budzi-sławskie and Wójcińskie Lakes (1874). Valleys of smaller rivers were meliorated in the years 1855-1864 and the beds of rivers, such as the Samica Stęszewska (1853), Orla, Dąbroczna, Barycz, Ołobok and the tributaries of the Ciemna, Samica, Flinta, Sredzka Struga, Miłosławka and Lutynia were cleaned out.

In the second part of the 19th century, following the great flood of 1855, work began on the regulation of the upper Noteć river between Goplo Lakę and the Nakło and Bachorskie and Parchańskie Marshes. The biggest land melioration company (the Obra River Land Melioration Society) covered an area of around 25 thousand ha, and the smallest — 7.31 ha.

The inerease in the number of these companies was very slow. In the first 30 years (1842-1872), 1 to 2 companies per year were established. In each of the years 1842, 1851, 1852, 1855 the establishment of only one company took place, two companies were set up in the year 1856 and so on. Only in 1876 — 4 and in 1869 — 5 were larger numbers of companies established. The sizes of the areas covered ranged between 62 and 6000 ha (with the exception of the Obra River company covering 24 900 ha). In the next 28 years (1872-1890), from 2 to 8 new companies appeared every year. The year 1891 began the prime time for their development.

The following data present a generał picture of the development of land melioration companies (Łukomski 1935):