The paper present the detailed assessment of water retention possibility in the lakes situated in the Struga Dormowska River. These activities were important to increase satisfy water needs warranty of fish ponds. Struga Dormowska is the third rank river, the left tributary of the Warta River. The area of the catchment amounts 57.2 km2. The catchment has an agricul-ture-forest character and high lake density. Struga Dormowska flow through twelve lakes, which have an area of 240 ha. The area of each lake range from 2 to 79.6 ha. The catchment has a very small water resources. Specific runoff of the catchment equals about 2 dm3.s-1.km-2, and runoff coefficient about 0.1. The researches reveal that increase of lakes water retention allows to obtain high amount of disposal water, that allows to increase water needs of the fish ponds warranty satisfy located in the middle and lower part of the river. The estimation was based on amplitudes of water level in the lakes, elevation-storage curves and inventory of hydraulic structures along the river. Damming of the water in the seven lakes from 0.2 to 0.3 m in natural water level oscillations allows to gain about 0.4 mln m3 water in the usable ...
The aim of this research was an assessment of impact of relocated Mała Wełna river channel on water conditions in the adjacent areas. In this paper also a fasibility to increase river flow capacity with the purpose of maintaining river channel dynamic equilibrium was presented. Field observations and measurements were carried out in hydrological years of 2000–2008 in Mała Wełna river catchment down to Kiszkowo crosssection. The main cause of valley flooding on the reach from Zakrzewo to Kiszkowo were hydraulic conditions at the relocated Mała Wełna river channel. The river cross-section geometry and its channel slope caused that at the high-water discharge SWQ the channel capacity of the river is too low. A lack of the river banks and bottom maintenance has had strong negative impact on the river capacity. To improve the river flow capacity and the drain ditches “A” and “B” it is necessary to make modernization of hydraulic structures and the whole water system in the catchment of the Mała Wełna river. Before this it is necessary to make a detail geodetic measurement of these areas. ...
The aim of this paper was assessment of flood risk in the catchment of the Mała Wełna River on the reach from Gorzuchowskie lake to Kiszkowo weir No 1 (Brudzewko). The annual maximum discharges with given probability of exceedance 10%, 1% i 0,2% were calculated on the basis of data obtain from the Polish hydrological year-books: 1965-1975 and 1978-1983, and own data for the period 2000-2009. The maximum annual discharges were calculated on Institute accord-ing to the Meteorology and Water Management (IMGW) method, where the distri-bution of probability of exceedance of the annual maximum floods is calculated as the probability of alternative of two non-eliminated independent events. The max-imum annual discharges with given probability were inputted to RUBiKoN hy-draulic model, which allow to calculated localization of points of the highest water level on the cross-section of Mała Wełna river channel. Digital elevation model of the river valley were performed on the basis of topographic maps in the scale 1:10 000 with use of ArcGIS program with Spatial and 3D extension. Water levels in cross-sections and digital elevation model allow to establish the area where the flood risk probability is low (one on 500 years), medium (one on 100 years) and ...
In this work analysis and assessment of physico-chemical status and fish structure of the Mała Wełna River for a period of 2000-2009 are presented. Based on the values of oxygen indexes (dissolved oxygen, BOD5 and COD) and biogenic indexes (ammonia nitrogen, nitrate), noted during research period, waters of the Mała Wełna River was classified as moderate quality. Results of the fish structure study carried out on 7 reaches situated along course of the river showed that both abundance and biomass varied among particular measurements points (Shannon's index amount 0.9). Fish population was represented by 18 species, among them in 2008 pike constituted 47% of the biomass but the highest abundance showed sticklebed (32%) Among 18 species occurring in the waters of the studied river 15 of them were classified to a category of lower risk of endanger and 3 as en-danger species. Similar to water quality also ecological status of the river was evaluated as moderate.
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