West Polesie Biosphere Reserve - Poland

The area of the ?West Polesie? Biosphere Reserve is located within the Lublin Polesie, in the region of very shallow groundwater occurrence, numerous lakes, ponds and a dense network of drainage ditches. Observations of land give impressions of wealth of water, whereas in fact it is a large area of its deficits, very strongly noticeable during the long summer rainless periods. Field factors decide about small resistance of environment - unique in Europe. Its high value and attractiveness of science, nature and landscape is mainly determined by water relations. In historic times the area of the Polesie were numerous in swamps, marshes and bogs, as well as large areas of forests, which determined the practical unavailability of the land for human. This area for centuries was very sparsely populated and extensive economy did not cause significant changes in the environment. The origins of human intervention was associated with both the cutting of the forest and the drying of moors. This resulted in the formation of specific islands - developed areas on a small part of the Polesie. It should be clearly emphasized that the conditions of the geographical environment decided that till the mid-twentieth century this region was a sparsely populated with traditional agricultural and livestock economy. Determined severity of human intervention occurred after 1954 - after the commencement of the construction of the Canal Wieprz-Krzna and the associated with it, early planned drying the area (Wilgat et al. 1997). In the region more and more visible changes caused by: intensification of agriculture, increase the availability of communications, the increasing tourism and recreation, and investments related to the exploration for and the acquisition of rock materials and energy, as well as the construction and operation of large quantities of groundwater intakes began to occur. Water relations in the area of the Biosphere Reserve, as well as the whole Polesie are formed under the influence of terrain and climate factors, mainly geological structure and permeability of the soil, relief, precipitation and evaporation. Rocks of the Cretaceous age that are formed as marl and writer chalk and surging on them Quaternary deposits are the main factors decided about Polesie? water resources. Ceiling of Cretaceous carbonates generally decreases toward the north, which is important for the water relations area. These rocks in the ground elevation areas appear almost on the surface. Their shallow occurrence is highlighted by the numerous karst forms appearing on the hummocks constructed from Cretaceous rocks. Power conditions and water flow are relatively weak , because the flow of water occurs through different lithological Quaternary deposits, sometimes very poorly permeable. In zones of outcrop of the Cretaceous rocks free water table is maintained on the depth of several meters, and outside these areas water of Cretaceous levels have thrusting character. Size of hydrostatic pressure depends on the size of backfilling by quaternary sediments. Waters of the Chalk level are drilled at a depth of 10-50 m, locally up to 80 m, and usually stabilize at a depth of several meters. Filter coefficients reach most often several meters per day, and the yields obtainable from wells ranges from a dozen to 100 m3/h. The amplitude of groundwater range is very diverse and has little relation with the depth of water occurrence. Lifting and lowering of the water table is fairly quick, and high states last short. In the long-term periods a seasonal and annual variability of water levels is marked, as well as the abundance of water the area is heavily dependent on atmospheric supply. In the rhythm of seasonal, the maximum water levels usually fall in April. In the following months, the water table is lowered to the minimum conditions noted at the beginning of autumn. During the fall and winter a replenishment of water resources throughout the region takes place. In the summer months, although the highest rainfall, structural water deficits, mainly due to high evapotranspiration are observed in the region of the Polesie. The mean amplitude of fluctuations in the water level exceeds 1 m, and the extreme differences in water levels reach 3 m It should be underline that, despite the diversity of lithological aquifers and variable thickness of the vadose zone, underground water table fluctuations take place synchronously (Wilgat et al. 1984). This indicates a hydraulic relationship of aquifers and the dominant role of the power of rain and melting in rectifying water resources. The main component of the hydrosphere of the ?West Polesie? Biosphere Reserve are numerous lakes and other surface water reservoirs. A group of lakes of the ??czna - Wlodawa Lakeland in the 80?s XX century consisted 67 lakes (Wilgat et al. 1991), 61 of which are natural lakes, and 6 were converted into reservoirs. The vast majority of those tanks are small - the largest has 284 hectares - but with poorly developed shoreline. The depths of the lakes are varied, but shallow and very shallow dominated, and the deepest exceed 30 m. Capacity of individual lakes are small, usually 1-2 million m3. Reservoirs and lakes that storage waters in nig quantity are: Lake White near to W?odawa - 15.0 million m3, Lake Piaseczno 10.7 million m3 and 9.2 million m3 ? Lake Usciwierz. The volume of water stored in all the natural lakes and converted into reservoirs is only 107 million m3. Most lakes are heavily overgrown, and numerous depressions now are filled with peat and gytia what indicate advanced stage of lakes dissapearance process. They represent various trophic types, thermal and hydrochemical and are characterized by slow water exchange. The archival materials include only limited information regarding to fluctuations in lakes? water level. In the years 1957-1967 for the Forestry Research Institute water levels in the lake Perespilno were recorded. In contrast, observations made by the Institute of Meteorology and Water Management were performed from August 1 1971 to July 1982 in two lakes: Piaseczno and White Wlodawskie. In the following years, fixed or periodic numbers of water levels in the lake have been performed in the Lake Piaseczno by the Department of Hydrography, University UMCS in Lublin (Wilgat et al. 1991). In the period 1990-1992 workers of the Bogdanka Coal Mine were performed to level measurements of water levels in several lakes, in 1991 in 16 lakes water measurements tolls were established - by the Hydrographic Department, the Coal Mine Bogdanka and Poleski National Park in Urszulin. In 1993, the Head of the Chelm Landscape Parks launched - first systematic and in recent years only temporary - readings of water levels in 29 lakes of the eastern part of the ??czna ? W?odawa Lakeland. In total, in 1991-2005 water levels were recorded in the 38 lakes. The amplitudes of the water levels in the lakes vary widely - from 42 to 171 cm, and their size varies with increasing of observation period, that is, the periods of appearance of extremely dry or humid. A small amount of outflowing water, and the great flatness of the region is not conducive to natural erosion processes leading to the creation of networks drain. Rivers of the Polesie flowin the valleys of poorly formation, and the amplitude of fluctuations in the water level in the trough reaches 2-3 m. The largest river, W?odawka, poured into the Bug river average of 2.2 m3 / s of water, variability of flows of 0.12 m3/ s to 48.2 m3 / s. With no other rivers within the Biosphere Reserve does not carry 1 m3 / s. Average outflow unit is about 3.5 l / s ? km2. In some periods flows fall to very low values and drain the unit does not reach 1 l / s ? km2 , and during long-term drought even 0.5 l / s ? km2. These values underline the scarcity of Polesie waters. The outflow from the basin shows a clear annual cyclicity, the seasonal rhythm of the river runoff typical of rain-snow power. After strongly marked maximum outflow in March, the minimum occurs in late summer and autumn (Michalczyk, Wilgat 1998). This is a consequence of the rapid depletion of scarce underground resources. During the spring (March-May) flows 41 % of water, much less in summer (June-August) - 18% and even less in the autumn (IX - XI) - 16%. Considering the International Biosphere Reserve, consisted of Polish, Belarus and Ukrainian part of the Polesie, by its centre flows the Bug river, taking beginning in Go?ogóry in Ukraine. Bug river valley on section of the Polesie has a meridian course, and its width in some places exceeds 10 km. Rating of width of the valley is quite difficult, because the surface of the terraces lagoons often passes without clear boundary in the broad area of denudation and accumulation. At the height of the Wola Uhruska and W?odawa cities, valley has a groundbreaking character. Narrowing and expansion of the valley are characteristic for this section and its sculpture stands out wide from 1.5 to 4 km flood plain with numerous meanders cutted off in part filled with water. Its amount ranges from 1.5 to 3.0 m above the mean water level in the trough. Over a contemporary valley botton of the terrace, a level rises to a height lagoons from 3 to 7 m (Szwajgier et al. 2002). According to materials given by ImiGW, the average flow of Bug in a profile in W?odawa was 54.5 m3 / s , and the extreme values varied over a very large range of values - from 8,01 m3 / s to 769 m3 / s. The lowest recorded state was 62 cm and 506 cm the highest. With increase in water levels, the width of the river increases, in extreme cases even up to several kilometers.