Limnetica 30

The improvement of the ecological status of many heavily modified water bodies in Europe is a priority of the European Water Framework Directive. This paper evaluates the physical river habitat quality of the Bílina River, one of the most polluted and heavily modified rivers in Central Europe that is mainly classified as a heavily modified WB. The physical river habitat was evaluated using the Ecomorphological River Habitat method (EcoRivHab) and the LAWA Overview Survey method (LAWA-OS). The EcoRivHab method uses field surveys as data input in which the hydromorphological status is determined by 31 parameters, while LAWA-OS is based on the assessment of 17 parameters using available data and mapping resources. Human activities that affect the Bílina River are primarily the expanding coal mining operation and chemical industry, which negatively influence physical river habitat condition. The majority of the reaches of the Bílina River have become embedded, straightened and reinforced, with almost no natural vegetation in the riparian zone. Based on the results of this study, the Bílina catchment was identified as having a strong anthropogenic impact, primarily due to the high amount of reaches in ecological class (EC) IV (20.5 % EcoRivHab; 34 % LAWA-OS) and V (27.8 % EcoRivHab; 29 % LAWA-OS). These reaches were located in urban and mining areas. Significantly lower proportions of reaches were classified in EC I (2.5 % EcoRivHab; 7.5 % LAWA-OS) and II (9.5 % EcoRivHab; 7 % LAWA-OS), which are located on the upper course of the Bílina River. Differences between methods in the hydromorphological evaluations are caused by a variety of observed parameters, including different delimitations of river zones and widths of the scoring intervals. This study demonstrated the possibility of applying both methods in assessing heavily modified and artificial water bodies.