Native versus invasive crayfish in the Czech Republic
A decrease in species diversity is a negative consequence of many human activities. The number of native animal and plant species is decreas-ing, their populations are shrinking or completely disappearing, the number of endangered species is increasing, and non-native species are spreading. Global problems are perhaps most evident in the example of freshwater ecosystems.
Invasions of non-native species, associated with high cultural-sociological and economic losses, are currently considered one of the most sig-nificant factors in the decline of species diversity. For these reasons, the issue of non-native species is receiving considerable attention world-wide.
There are currently six species of crayfish living in the wild in the Czech Republic, of which only two are native: noble crayfish (Astacus asta-cus) and stone crayfish (Austropotamobius torrentium). Narrow-clawed crayfish (Astacus leptodactylus) is a European species but not native to the Czech Republic. Other species – signal crayfish (Pacifastacus leniusculus), spiny-cheek crayfish (Orconectes limosus), and marbled crayfish (Procambarus fallax) come from North America and are invasive species [1, 3].
Assessment of trends in concentrations of chemical and physico-chemical indicators of the status of surface water bodies
This article presents the results of trend assessment of selected chemical and physicochemical indicators of surface water status. The assessment approach is based on a similar procedure for assessing significant upward trends of pollutants and trend reversals in groundwater bodies. The procedure is based on measured concentrations from 2010 to 2018 and estimates concentrations at the end of 2021, 2024, and 2027. For the trend assessment, data from Czech river basin state enterprises were used to assess the ecological status/potential and the chemical status of surface water bodies. However, only part of the profiles with measured concentrations met the time series requirements. The assessment of trends towards the end of 2024 and 2027 shows that some indicators (polyaromatic hydrocarbons, adsorbable organically bound halogens – AOX, and nitrate nitrogen) are projected to improve compared to the status as of 2018. On the other hand, a slight deterioration is predicted for biochemical oxygen demand, dissolved nickel, and ammonia nitrogen.
Optimization network model of water management systems
The paper describes software aimed at analysing water management infrastructure and identifying critical points for water supply and assessing possible measures aimed at optimising the water supply function of the water management system. The computational procedures integrate the evaluation of the hydrological characteristics of the area, the parameters of the water management and water supply systems and the water supply requirements. The solution uses graph theory and network flow optimization (out-of-kilter algorithm is applied). The program is implemented as a PC application and equipped with a user interface.
Risk assessment as a comprehensive approach to protection of drinking water sources
Drinking water supply as well as its quality form one of the basic pillars of modern society. This corresponds to the goal of the International Water Association (IWA) – good, safe and drinkable water, which enjoys consumer confidence and can be not only drunk without fear, but in which the consumer also appreciates its taste and aesthetic appearance. In order to meet these objectives, it is important to set drinking water quality requirements and also to keep the whole process of drinking water production and distribution, including all risk areas, under continuous control.
TGM WRI HEIS: 25 years of development and operation of the information system
V letošním roce je tomu rovných 25 let od zahájení vývoje (a následně pak provozu) Hydroekologického informačního systému VÚV TGM (HEIS VÚV). Tato doba je z hlediska kontinuálního vývoje a provozu informačního systému v současném prostředí takřka neustálých technologických a organizačních změn téměř úctyhodná a zcela jistě si zaslouží jak alespoň malé ohlédnutí za uplynulým obdobím, tak také stručnou rekapitulaci zaměřenou na současnost informačního systému (čtenář může namítnout, že zde by se nabízelo zmínit se podrobněji i o výhledu a plánech do budoucnosti, v této oblasti si však spekulovat příliš netroufáme, a proto ji zmíníme pouze stručně v závěru textu).
Preservation of drinking water demand from water reservoirs in climate change conditions
This study presents interim results of an evaluation of a potential climate change impact on the preservation of drinking water demand provided by water reservoirs in the timeframe of the year 2050. Hydrological and water sources and demands balance procedures have been applied, including modelling of the storage ability of water resources and water supply systems.
