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Wetland reclamation

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Wetlands of the Žuvintas biosphere reserve before reclamation

Žuvintas and Amalvas wetlands formed in depresions left by the last glacier more than 10 thousand years ago. Until 6th decade of the XXth century they covered more than 10 thousand hectares.  Local people fished in shallow Amalvas and Žuvintas lakes, collected cranberries in the bogs and used fens for cattle grazing and moving.  Due to high water levels, farming was difficult and grass quality poor. Intensification of agriculture in the 6-8 decades of the last century led to implementation of big scale land reclamation activities in the Dovinė river basin that radically changed the area. 

Wetland reclamation on the second half of  XX century

The Amalvas wetland complex was influenced by human activities to higher extent than the Žuvintas wetland. Land reclamation had resulted in the drained area covering 2160 ha, i.e. more than half of the area.

Northern part of the Amalvas wetland (former fen and transitional bog) was established as a winter polder (total area 638 ha) with meadows and pastures. Groundwater level in the polder was reduced by more than 2.0 m what in turn affected water level in the neighboring bog.

Southern part (former active raised bog, bog woodland and swamp woods, ~1520 ha) was intersected with drainage channels. Approximately half of it (former fen, swamp woods, transitional mire) is privately owned and used for agriculture. Second half (degraded raised bog and swamp woods area) is state owned and managed as forest land. Water level there is kept by drainage channels ~0.6 m from the surface.

In order to stop water-flow from the remnant of the Amalvas wetland to the newly established agricultural areas the dike and the sluice-gate on the outflow from Amalvas Lake were built in the south-eastern part of the wetland. The dike directs spring flood water to the sluice-gate, however does not prevent seepage from the intersected deeper layers of the very bog to the ~4 m deep drainage channel going along the dike, what results in increased drainage and following subsidence of the peat in the neighboring bog woodland.

The drainage channel goes along the western edge of the Amalvas wetland as well. Protective dike built against the channel prevents water runoff during spring floods. There is water seepage to the channel, however it is less significant as majority of it is dug in the fen peat and mineral soil. The seepage increases in the southern part of the channel where it gets deeper and closer to the bog.

Land reclamation activities affected the Žuvintas wetland as well. Two drainage channels (total length ~5 km, average depth 1,5-2 m, width - 5-7 m) in the southern and one (~0,5 km, 4-6 m width, 1-1,5 m depth) in the northern part enter the very raised bog and bog woodland.

All the northern part (former fen and transitional mire) of the Žuvintas wetland was drained and water level lowered to enable farming in the area. The protective dike was built against the channel going along the northern wetland boundary. It sustains spring flood water, but there is seepage in the certain areas where the bog peat is intersected.

Sluice-gate was installed on the outlet of the Žuvintas Lake in order to use the Žuvintas Lake as a water reservoir.

© 2009 „WETLIFE“ LIFE07 NAT/LT/530 .

sprendimas: IMODUS