Olszewski tube

A Olszewski tube is a device for deep- water drainage from lakes; it is a simple method to preserve lakes before eutrophication or even from tipping over or redevelop eutrophic lakes. This requires that the flow rate of the sea is sufficient to achieve a rehabilitated effect. It is named after the limnologists Przemysław Olszewski, who applied the method in the 1950s on Kortowo Lake in Poland for the first time. The idea has already been published in 1944 by the Swiss biologist Eugene A. Thomas.

Construction and operation

A tube is laid between the lowest point at the bottom of a lake and the place of the superficial runoff. The natural superficial drainage is closed by a lock, so that only the nutrient-rich deep water can flow through the tube. To no pumping capacity is required. The low water flows according to the principle of communicating vessels of itself, according to the natural runoff.

Occasionally the lock of the effluent is also designed as an overflow so that if necessary, more water can leave the lake, as the Olszewski tube summarizes.

The same principle of a deduction in deep water you use in the carp pond by the manner of construction of the flow structure, the so-called monk. Here, the low water rises up between two rows of boards. The pool -side row to the base includes a grille for the passage of the water, which then passes over the upper edge of the outer row in the drainage boards.

The purpose of the deep-water drainage

In a lake is usually in summer and in winter a temperature-induced density stratification from. In the near-surface regions, the nutrients, especially phosphorus and nitrogen bound by primary production in biomass particles. In this form, these nutrients decline, in part, into the deeper water layers. There they remain trapped until the onset of the next full circulation, even if they by some degradation processes accept a dissolved form. So the near-bottom water layers are enriched with these nutrients. Therefore, a deduction is precisely this water through the Olszewski tube removed very efficiently the nutrients from the ecosystem.