Water is one of the main elements of the environment which determine the existence of life on the Earth, affect the climate and limit the development of civilization. Water resources management requires constant monitoring in terms of its qualitative-quantitative values. Proper assessment of the degree of water pollution is the basis for conservation and rational utilization of water resources. Water quality in lakes and dams is undergoing continuous degradation caused by natural processes resulting from eutrophication and due to anthropogenic reasons. One of the tools that are used to solve problems of surface water pollution is modelling of changes which take place in lake waters and associated water quality changes. In the last thirty years a rapid development of mathematical modelling of water resources quality has been observed. A number of computer models have been designed which are successfully applied in practice in many countries, including Poland. This paper presents an overview of mathematical models for assessment of water quality in dam reservoirs. Description of the WASP program which will be used for modelling water quality in the Sulejow Reservoir was the focal point.
This paper reports the processes by which a single-phase 3-D CFD model of hydrodynamics in a 17-km-long dam reservoir was developed, verified and tested. A simplified VOF model of flow was elaborated to determine the effect of wind on hydrodynamics in the lake. A hexahedral mesh with over 17 million elements and a k-ω SST turbulence model were defined for single-phase simulations in steady-state conditions. The model was verified on the basis of the extensive flow measurements (StreamPro ADCP, USA). Excellent agreement (average error of less than 10%) between computed and measured velocity profiles was found. The simulation results proved a strong effect of wind on hydrodynamics in the lake, especially on the development of the water circulation pattern in the lacustrine zone.
The paper presents methodology of accurate mobile measurements of water quality parameters such as temperature, dissolved oxygen, chlorophyll “a” concentration, ammonium ion concentration, conductivity, pH and blue-green algae content in water. The measurements (probe EXO 2, YSI, USA) were made on various depths of probe immersion (1.5, 2.5 and 3.5 m) and at different towing speeds of the probe (approx. 5.4 and 9.0 km/h). Static measurements carried out on the same route provided reference values for the measurements in motion to compare the repeatability of static and mobile methods. The tests were also evaluated by observation of probe behavior in motion, e.g. water disturbance intensity, access of light (sun rays) to the sensors. Statistical tests confirmed that the mean values of water quality parameters from mobile measurements with the speed of 5.4 km/h at the depth 1.5 m does not differ from the stationary measurements. Results of statistical analysis prove that water quality parameters can be measured accurately keeping established speed of towing the probe at the fixed depth. Methodology of mobile measurements elaborated in the frame of this work allows to collect vast number of data which can be used to obtain GIS point maps of water quality parameters in large water bodies.