THE ZUIDER ZEE.

Press, Volume LXVI, Issue 19853, 14 February 1930, Page 11

THE ZUIDER ZEE.

LAND FROM THE SEA BOTTOM. AMBITIOUS UNDERTAKING. A resident of Christchurch, who returned recently from a visit to Holland, told a representative of Tn» I'ress yesterday that lie had been specially interested in the cable message in The Press of Wednesday last, in reference to enclosing and partially reclaiming the Zuider Zee. He had learned, when in Holland, from people with whom he had discussed the. matter, and from a publication relating to the work, that it consists of two parts —the enclosing by which the water of the North Sea is to be separated from the enclosed part of the Zuider Zee, and the reclaiming, by which parts of the enclosed area are to be embanked by dams from the remaining water, and to be drained by pumps m order to mnko the reclaimed, bottom of the sea inhabitable and fit for cultivation. A dam is to be built across the sea, stretching from the North Holland ooast across Wieringen towards the Friesland coast. The first part of this dam has a length of about 1* miles, and is already finished. The part between Wieringen and Friesland, a length of about 18J miles, is at present in course of construction. South of the enclosing dam four polders arc to be reclaimed separately, leaving out a large area of water, provisionally called the Yssel lake. lms lake is to collect the of the rivers Yssel and Vecht, and of some other small rivers and arterial drainage systems, besides the water pumped from the reclaiinea polders. The surplus water from Yssel lake is to be discharged into the open part of the Zuider Zee. The discharge Will take place through 25 sluices, each sluice-way being 40ft wide. Yssel lake will in future be of great importance to the province of Friesland, and the northern part of North Holland, as it will become a vast freshwater basin. Once the enclosing dam is completed, the Yssel lake, which ; originally contained sea water, by the discharge of the rivers will, after a short period, become a fresh-water take from which the surrounding cultivated areas will draw a supply in time of drought, and it will agricultural purposes as well as navigation by maintaining the desired level in the canals of the surrounding country. The dam is being built of materials obtained from the bottom of the Zuider Zee. In constructing the . dam, .first; a core of boulder clay, dredged from the sea bottom, is raised, then Band dredgedby suction dredges is dumped, by means 'of hopper barges, behind the .boulder clay, or deposited by pumpng dredgers discharging it from barges, through pipes.. The lower portion of the aam •.is protected from wave action and scour below the water-line by covering tho slopes with mattresses of brushwork, weighted with stones, and above the ; water-line by stone pitching of basalt, or limestone, above which is turfiiig. There are four polders to be reclaimed from the enclosed area of the Zuider Zee, the total area to be reclaimed being 550,000 aeres—-or 7 per cent bf the total surface of the Netherlands, and 10 per cent, of the surface of thp arable soil. The arable soU will lie chiefly within the polders, while the greater part of the sandy soil "will fall to the Yssel lake. This lake will have an area of 270,000 acres. Eastward of Amsterdam another lake —the Y lake —of about 20,000 acres, will be left, separated from Yssel lake ljy locks. : - _ It is expected that the enelosinE . the Zuider Zee will be finished in 1934; and'that the whole scheme will be completed in 1952.