Consecinţe ale colmatării canalelor de desecare, în sistemul de desecare-drenaj Rotopăneşti-Rădăşeni-Fântâna mare, judeţul Suceava

Abstract

According to the data offerred by the National Agency for Land Improvement, in Suceava county there is a surface of 44904 ha with drying up workings, of which 27455 ha with drainage workings. The network of drying up canals is 1875 km long and the undergroung drainage network is made of absorbant collector drains and has a total length of 11909 km. After 27 years of exploiting the network of drying up canals, a modifications of the geometrical and structural parameters have occurred (depth, width at the bottom, the embankment coefficient and the light of the canal) through bank errosion and clogging of the canal bottom. The degree of bank errosion and canal clogging in the drying up and drainage systems is influenced by water velocity, the stability of the embankments and the weed growth, as well as the use category of the surfaces disserved by the canals. In the case of dried up and drained surfaces used as pastures, the bank errosion and canal clogging is more obvious and the medium occurring ratio is almost double comparing to the one of the canals which disserve surfaces used as arable land and hayfield. On the surfaces used as pastures, weed growth is more reduced, and on some areas there is no grass at all, a result of uncontrolled grazing and canal crossing by animals, during periods with excessive himidity. As to surfaces used as arable land, the embankments of the canals are covered with grass, which, on one side reduces bank errosion, and on the other, if left unmown, after some time, it favors the appearance of hydrophile vegetation and shrubs, hindering the water flow and clogging acceleration. The clogging of the canals blocks the evacuation holes of the drens, especially the collector drens which are deeper. Considering the relatively large surface which a collector-drain disserves, the obturation of the evacuation hole must not be neglected and urgent remediation measures must be taken, as it may require the whole collector-drain to be put out of function and lead again to an excessive humidity on the entire surface disserved.