Rivers, lakes and wetlands
In the Park the river network is poorly developed. Major rivers are absent and there are only relatively large sources of the rivers Polomet and Avon. River valleys in the upper reaches are poorly developed. Floodplains are often absent. The width of the rivers 5-15 m, with winding rivers, sandy soil, steep, sometimes steep banks, depth from 0.2 to 1.5 m and current velocity of 0.5-1 m/sec.
The watersheds between the Baltic and Caspian basins not everywhere clearly seen. A significant portion of the hydrographic network consists of rivers with a catchment area of 2000 km2 and 10 km long.
The main rivers of the Park: Seguranca (length 20.6 km), Impressive (1,8), Kletno (8,7), Valdice (16), Polomat (40,5), Soninke (7,7), Annica (25,5), Orlovka (12,6), Avon – basin of the Baltic sea; Libya (13,8), Avon (11,4), Zaporizka (19,9) – the Caspian sea.
Rivers are snow food. High spring tide, low summer low water, interrupted by rain floods (1-2 times a season), and sustained low winter low flow – characteristics. As the territory is characterized by unstable weather due to frequent changes Atlantic and Arctic air masses, in General, for the territory is characterized by an excessive amount of moisture. The average annual precipitation far exceeds evaporation and it is the main food of many lakes and rivers. Moisture conditions determine the fluctuations in the water regime of rivers and lakes, so long as it is subject to change, and centuries-old fluctuations.
The territory is characterized by a large number of lakes (76) different sizes and shapes. They are mainly of glacial origin with sublime beaches, rugged coastline, uneven bottom topography, with pits and Islands. Some lakes have a pronounced process of modern waterlogging. There are lakes with inherited basins (Valdai lake). Lake depth does not depend on their size. Often small lakes are considerable (8-10 m) depth, and large – Nahodne, Dorise (2-2. 5 m) is small. The levels of lakes depend on precipitation. There are lakes of karst origin – Gorodno, Streamline, water regime which is different from the usual lakes.
Bottom soils of the lakes are varied: rocky, sandy, pure or with admixture of silt, gravel mixed with sand, some with sapropel.
The total water surface area of lakes 14704,5 ha.
Everywhere small patches of bog occur. Only in the valleys of Palometa and Avon there are large marsh areas. Watersheds there are riding the Moors on the site of former lakes. To overgrowing of lakes causes a decrease in the level of surface water and groundwater.
The largest bog areas are: cyanosis in damanskom area (the bog area of 140 ha); the tract Gagarin, Kikino, the Big Loon – raised bogs with an area of, respectively, 390, 240 and 168 ha of the bog of Verevkina area of 90 hectares in the Okulovsky district. Other swamps small areas of 15-20 ha.
Water bodies of the Park have undergone significant anthropogenic impacts from human settlements, industrial enterprises, agricultural facilities and recreation. The most affected lake Valdai, Morocco, Dorise, Ploticyna, Moiseev, Tehran, Average, Lucenec B., Putilov, Impressive, Krivtsovo, Onion and Dolotzo. The most clean lake: Boree, Sadagora, Russian and Dinner (Valdai district), and Seliger, velyo (Demyansk area). The perfect transparency of the different lake Streamline.
Rivers and lakes are rich of fish fauna. About 45 species of fish, including such valuable, Peled, carp, smelt, vendace, pike, whitefish, vendace, burbot, eel.