This paper presents the evaluation of the risk factors in the watercourses which will be regulated or maintained in the future. The analysis concerns one of the components of the ecological risk – the risk of the qualitative and quantitative changes by the aquatic plant communities. The basis of the analysis were field studies, which were carried out during the years 2007-2008 in six lowland water-courses in the Lower Silesia. On the river beds there were executed regulation or the maintenance works. The field studies comprised identification of aquatic plant species and es-timation of their cover-abundance. For the abundance analysis we used the Braun-Blanquet Scale. At the natural transects the number of aquatic plant spe-cies ranged from 4 to 7, and abundant from 5 to 100% of the bottom surface. At the altered stretches the number of aquatic plant species ranged from 0 to 5. The plant abundant did not exceed 25% of the bottom surface. On the ground on these dates were prepared a maps of ecological risk, which can be used in planning and execution on watercourses regulation and maintenance works. ...
In this paper we described the process of watercourses maintenance and analysed the problems involving its quality management in terms of the water-course efficiency. The watercourse efficiency is determined by running waters use and maintenance works. Both actions are characterized by good quality when the good technical condition of the river-bed, its capacity and the good ecological status are provided. River-bed capacity ant the ecological status of the running waters are influenced by the aquatic plants. Therefore control and assessment of aquatic plants abundant are major elements of the quality management of the wa-tercourses efficiency.To identify the problem of overgrowing of running waters with plants, the lowland watercourses in the Lower Silesia were investigated during the years 2007-2009. Field studies showed, that the overgrowing of river-bed begins straight after the maintenance works. Generally the aquatic plant development is rapid. Therefore the correct watercourse maintenance demands cyclical mainte-nance works. Maintenance works comprise a lot of technical actions, which are related to each other. In this paper we showed, that each of these actions affects the watercourse efficiency. The field studies and analysis proved, that quality management of the watercourses maintenance requires establishment criteria of the process quality assessment. Criteria should consider ...
This paper attempts to assess an effect of the range of regulatory works in watercourse beds on the aquatic plant communities. The results of field studies carried out on sections transformed as a result of regulatory works and the non-altered sections were compared for this purpose. The field studies were conducted in growing seasons in years 2008-2014 on 11 small and medium-sized lowland watercourses in Lower Silesia. They included identification of aquatic plant species and estimation of the degree of bottom coverage with them. The assessment was based on analysis of changes in the values of five biological indicators such as: the number of aquatic plant species, Jaccard similarity coefficient, ecological status, Shannon-Wiener biodiversity index and Pielou`s evenness index. Comparative analyzes enabled to determine the qualitative and quantitative changes in the aquatic plant communities. However, they did not show any correlation between the analyzed biological indicators and the range of regulatory works in watercourse beds. ...
