Volume 15 (2015): Edizione 4 (December 2015)

The Pietraszki water reservoir is designed for the lower part of the River Sufraganiec catchment (61.43 sq km), in the area of Kielce. In those conditions water volume is designed to be about 1.4 hm³, and the reservoir’s maximum depth, 4.2 m. The hydrological characteristics of the ungauged catchment of the River Sufraganiec are based upon the results of stationary field observations held in the cross-section located in the same place as the designed dam head. In the present analysis GIS techniques were also used, based on data obtained from the city’s Spatial Information System and WIOŚ in Kielce. Based on the Digital Elevation Model done with Airborne Laser Scanning, the reservoir area has been designated and its bathymetric and volume curves calculated. The mean annual values of specific runoff (8.8 l s^-1 km^-2), runoff coefficient (39%), runoff volume (17.2 hm³), specific discharge and the filling time have been determined. The analysis also took into account the annual cycle characteristics including minimum in-stream flow calculated with the use of a number of methods. The performed analysis shows that the River Sufraganiec water resources are enough for the fast filling of the Pietraszki reservoir (depending on the season - from 22 to 114 days), even when applying the most restrictive criteria in minimum in-stream flow calculations. The ecological quality of the River Sufraganiec water in 2014 did show any significant environmental threats. The analysis shows that the quantity and quality of the River Sufraganiec water is enough for the proper functioning of the planned reservoir.

The routine evaluation of water quality is limited to lakes with the largest area. In Poland, only lakes with an area exceeding 50 hectares are monitored by the State Environmental Monitoring System. For many local communities, however, small lakes are more important. This applies mainly to areas with a small number of lakes, where even the smallest lakes are used for various purposes. This paper presents the results of phytoplankton analysis in a small and shallow lake used for recreation. The study was conducted at three sites located in different parts of the lake. A total of 122 algae taxa were identified in the phytoplankton, mainly diatoms and green algae. The most constant taxa in the lake were: Stephanodiscus hantzschii, Desmodesmus communis, Pediastrum tetras and Crucigenia tetrapedia. The average phytoplankton biomass was 37 mg l⁻¹. The maximum biomass, almost 140 mg dm⁻³, was recorded in late July at the site located near the beach. At that time, there was a massive cyanobacterial bloom composed of Microcystis wesenbergii and Aphanizomenon issatschenkoi. Based on these studies, the lake should be classified as hypertrophic with bad ecological status. This lake should not be used for recreational purposes in the current state.

The article is dedicated to the problem of the transformation of rivers’ temperature conditions influenced by artificial reservoirs. A quantitative estimation of average water temperatures over ten days, and maximum and average annual water temperatures of regulated rivers downstream of reservoirs was made on the basis of the data analysis of a complete period of instrumental observations of the Republican Hydrometeorological Centre of the Republic of Belarus. It is established that the character and the parameters of the transformation of temperature conditions of the regulated rivers along with morphometric features of the reservoirs are determined by the meteorological conditions of the year and the operating conditions of the water-engineering system. The length of the cooling period effect varies from 20 days downstream of small reservoirs to 50-70 days downstream of small and average size reservoirs. The warming effect is less significant by temperature, but lasts longer and is appreciable around 200-240 days in a year. An increase in the average annual water temperature up to 0.5°C and a decrease in maximum temperature down to 1.1°C are observed in the tail-water of average size storage pools. Small size storage pools demonstrate an annual increase in annual water temperature up to 0.3°C and a decrease in maximum temperature down to 0.3°C. Small size water pools show an increase both in annual water temperature up to 0.5°C and maximum water temperature up to 0.3°C. Typical changes in temperature conditions of rivers are observed for a distance of 130 kilometres below the dam of average size water pools, along 70 kilometres in small water pools and along 30 kilometres in tiny ones.

The aim of this paper was to present the possibility of integrating LIDAR data with bathymetric measurements in order to assess the changes in water resources and morphometric parameters. The area of study was Lake Kiedrowickie (Poland). A change in most of the morphometric parameters has been observed. Especially important was the drop in water resources which amounted to more than 30%. A significant decrease (13.4%) was also observed in case of the lake surface. In conclusion we state that the integration of valid bathymetric measurements with the LIDAR data gives the full capability to model the changes of lake morphometric parameters with unprecedented accuracy. A significant complementarity and synergy of applying both techniques has been stressed.

The paper presents the results of the research conducted between November 2008 and October 2009. The research included seasonal dynamics of the flow and runoff of phosphorus compounds (TP and P-PO₄^3-), as well as Ca²⁺ and Mg²⁺ from 13 partial drainage basins of the River Drwęca. Water levels were registered automatically every day by recorders, and measurements of the flow were conducted once a month. Major differences were found in the water abundance as indicated by specific discharges in individual, partial drainage basins: from 1.87 dm³ s^-1 km^-2 (Lubianka - a lower part of the River Drwęca drainage basin) to 8.22 dm³ s^-1 km^-2 (Gizela - an upper part of the River Drwęca drainage basin). The studied rivers were characterised by very diverse average content of total phosphorus compounds: from 0.047 mg dm^-3 (Iłga) to 0.816 mg dm^-3 (Sandela); calcium: from 47.18 mg dm^-3 (Iłga) to 131.65 mg dm^-3 (Trynka); and magnesium: from 9.71 mg dm^-3 (Wel) to 36.76 mg dm-3 (Struga Rychnowska). Analysis of variance carried out on hydrochemical properties of the studied rivers divides the rivers into two separate groups: rivers with much higher content of phosphorus, calcium and magnesium compounds (Struga Rychnowska, Trynka, Ruziec, Lubianka, Kujawka, Sandela and Gizela), and a group of rivers with low content of these compounds (Brynica, Brodniczanka, Skarlanka, Wel, Iłga).