Poland Continental Waters

According to top-engineering-schools, 75.6% of the Polish territory (294.500 sq. Km.) Sends its waters to the Baltic Sea, and 24.4% (94.900 sq. Km.) To the Black Sea. The waterways of the two basins have very different characteristics. While the Baltic tributaries develop in very wide and flat basins, separated from each other by low undulations of the land, so that it was easy to connect them by channels, those of the Black Sea, except the Prypeć, have relatively limited basins and they flow in valleys embedded in the Podolic and pre-Carpathian shelves: such are the Dnestr and the Prut and their numerous tributaries. The former then have a much more regular regime than the latter and are widely navigable; their maximum floods generally occur in spring, corresponding to the melting of the snows; the lows occur in September or October. The 46, 7% of the Polish territory is drained from the Vistula (in Polish Wisła, in German Weichsel) which, originating in the Western Beskids not far from the border with Czechoslovakia at about 1100 meters above sea level, descends quickly to the plain, so much so that in Krakow, only 140 km. from the sources, it is already at 200 meters above sea level and in Sandomierz, at 280 km., at 150 m. In fact, 86% of its basin (about 200,000 square kilometers large, 181,400 of which in Polish territory) is located less than 300 m. in height, and more than a third (37%) under 150 m. Its course, on which, beyond Krakow, are Warsaw, the capital of Poland, and Torun, forms a large arch with the convex part facing E.; at the height of Bydgoszcz (a city located on its tributary Brda, a short distance from the confluence) it changes direction and turns towards the N., then forks and the right branch, the Nogat, it flows into Frisches Haff, and the left branch, the most important, forks again at about ten km. from the sea: one arm (Elbinger Weichsel), now almost completely covered up, also ends up in the Frisches Haff, another arm, which was once the smallest, threw itself into the sea after following for a certain distance the cordon of coastal dunes; but on February 1, 1840, following a flood, the river broke through the sandbar 12 km. further upstream, near Neufähr; and in 1895, then, a new outlet to the river was artificially opened, 18 km. Even further upstream. The last stretch of the Vistula (Vistula Morta) was transformed into a canal (a lock prevents floods and silting up) and Gdansk developed on it.

The Vistula has a course of 1070 km. and drags 2.7 million cubic meters annually. of solid materials, with which it has built a large delta (2000 sq. km.), facilitated in this by the fact that the Baltic has minimal tides and very weak currents. The flow of the river is on average 1000 cubic meters. per second, with minimums (September) of 400 cubic meters. and maximums (April) which also rise to 10,000 cubic meters. Boats of 200 tons. they can go up it as far as Dęblin, but in periods of high water the navigation is active up to Krakow with smaller tonnage boats. The Russians paid little attention to regulating its course, which instead had been appropriately placed in Prussian territory. Major works are underway (1935) to improve the navigability of the river, which a canal (Bydgoszcz Canal) connects to the Noteć (Oder basin).

Of the numerous tributaries of the Vistula, the most important is the Bug (on the right), which is 730 km long. and with a basin of 73,300 sq. km. It originates in the Podolic Shelf, and is a plain river, which flows in a wide and flat valley, accompanied by dead arms, ponds and marshes; the Królewski Canal joins it to the Prypeć (Dnieper basin); its tributary Narew, which receives many tributaries from the Masurian Lakes, is connected by the Augustów Channel to the Niemen basin. The Bug discharges into the Vistula downstream of Warsaw, but before its confluence the Vistula receives four other important tributaries, the Dunajec (240 km., 6960 sq. Km. Of basin), the San (450 km., Basin 16,870 sq. Km.), the Wieprz (285 km., basin 10,760 sq. km.) and the Pilica (310 km., basin 9720 sq. km.), the latter on the left, the others on the right.

Western Poland is part of the Oder basin, because it is drained by its most notable right tributary, the Warta (752 km., Of which 626 in Polish territory), which originates a short distance from the Pilica in Lesser Poland and receives the Noteć (German Netze, 360 km.). The Warta is poor in water, relative to the width of the basin (54,400 sq. Km.), Because it receives little rainfall, as we have already seen: however, navigation is active there downstream of Poznań, the most remarkable center that rises on its banks.

In eastern Poland, from N. to S., the basins of the rivers Dźwina, Niemen, Prypeć, Dnestr and Prut follow one another. The Dźwina (the Daugava of the Latvians and the Zapadnaya Dvina of the Russians) serves for a short stretch (80 km.) Of the border between Poland, the USSR and Latvia; its tributary Dzisna flows through Polish territory. The Niemen (length 992 km., Of which 407 in Poland; basin 91.900 kmq., Of which 52.200 Polish), born from the Pińsk Marshes and flowing into the Kurisches Haff, is a young river, formed after the retreat of the Quaternary ice; it was initially a tributary of the Vistula-Warta (see Vistula), and only in recent geologically it has turned towards the north, opening a passage through the Baltic Ridge. The Niemen in Polish territory receives the Szczara (330 km.), Which the Ogiński Canal connects to the Prypeć basin.

315 km of the Prypeć flow in Poland. out of 650 of the total course; over 57,000 sq. km. of Polish territory send their waters to this river, which crosses the Polessia, winding through numerous meanders and forming a labyrinth of bifurcations and dead arms.

The Dnestr arises from the Eastern Beskids to the West of Turka, and flows in Polish territory for 495 km. about 1380; of the 33,400 sq. km. which constitute its basin within the borders of Poland, 20% is located at a height of more than 500 m., and 50% between 300 and 500 m. It is perhaps the most tortuous river in Europe, and in fact flows with recessed meanders, 150 m deep, through the Podolic Shelf, forming a kind of corridor with very varied and picturesque aspects. Its tributaries, both those coming down from the Carpazî and those coming from Podolia, are characteristically parallel. Del Prut, a tributary of the Danube, only 130 km. they return to Poland; the Czeremosz, its tributary, partly marks the border with Romania.

Poland is very rich in lake basins, which number several thousand (the catalog drawn up by the Institute of Geography of the University of Warsaw lists about 3000 with more than 1 hectare of surface). Over a thousand of them are located in the Vilna region, N. del Niemen: and among them the Narocz, the largest of the Polish lakes (80.5 sq km), the Snudy-Strusty (63.5 sq km), the Dryświaty (44.7 sq km), the Drywiaty (37.8 sq km), the Dzisna (24 sq km), the Świr (22.5 sq km), etc. Other regions very rich in lakes are Polessia, which has more than 500 (Świteź Poleska, 28.4 sq km, Wygonowskie, 26.6 sq km, Czarne nad Jasiołdą 17.2 sq km, etc.); the Kuyavian, which has 270 (the largest is the Gopło, 23.4 sq km); the Suwałki region, with about 300 (including the Wigry, 21.3 sq km); the Dobrzyń region, with 190, and that of Lublin, with 104. The mountain lakes of the Polish Tatras are about fifteen, all very picturesque; among them we remember the Morskie Oko (0.30 sq. km.), the Wielki Staw w Roztoce (0.33 sq. km.), the Czarny Staw nad Morskiem Okiem (0.18 sq. km.). The origin of most of the lakes in Poland is due to the Quaternary glaciation (erosion of ice and subglacial waters, accumulation of moraines, etc.). As we have seen, there are few lakes of considerable surface area: according to S. Lencewicz only 25 of them have an area greater than 10 sq. km., and of these only two exceed 50 sq. km. The depth is also generally very small, and there are relatively few lake basins with a depth greater than 20 m; the maximum is found in the mountain Czarny Staw nad Morskiem Okiem (84 m., v.carpazî, IX, pl. XXXVII). The lakes of the Tatras are usually arranged in series sloping down the same valley, and this succession is to be related not only to the glacial modeling, but also to the movements undergone by the massif during the glaciation. The highest, on the upper step, near the head of the valleys, are small but deep circus lakes, enclosed by steep rocky walls, less than towards the valley; the lower lakes are usually barred by moraine bands, sometimes superimposed on rocky banks.

Poland Continental Waters