Assessment and ranking flood events in a regulated river using information and complexity measures

The availability of a robust approach that describe the hidden features of flood events in regulated rivers is of great importance. The key goal of this research is to utilize some of information and complexity measures to assess and rank flood patterns within a regulated river system. To meet this goal, the Metric Entropy (ME) as measure of information content and Rényi Complexity (CR) as a quantification for complexity content were employed. To examine the role of river regulation on flood risk control, river stage records of two monitoring stations located at downstream of two different dams were considered in this research. The findings show that information and complexity metrics offer an image of the randomness embedded in dataset and the presence of internal patterns in studied data records. In general, this research shows that natural environmental risks and disasters can be assessed and ranked using a promising physical scheme based on information and complexity measures.

Spatiotemporal distribution of planktonic ciliates in the Kuybyshev water reservoir in the area of Klimovskaya narrowing

The paper attempts to link changes in quantitative characteristics of the community of free-living planktonic ciliates and the nature of their vertical distribution with the operation mode of the hydroelectric power station in the reservoir. Low values of the abundance (8–1,560 thousand cells / m3) and biomass (0.1–66.9 mg / m3) of ciliates in the water column, and a fairly wide range of their variation in the reservoir are probably due to the oscillatory nature of the hydrological regime in the regulated river conditions. The vertical distribution of free-living planktonic ciliates of the near-dam section of the Kuibyshev reservoir was studied at all times of the day on all days of the week. The species were distributed throughout the water column to the bottom with some preference for the surface (0–2 m) and medium (4–10 m) layers. There was no clear attachment of individual species to certain layers in the conditions of homothermy. The preference for certain horizons is due to some biological characteristics of the species (for example, peritriches on the coenobia of algae in the surface layers), departure from “blooming spots”, etc. No data in favor of vertical migrations or “turbulent transport” has yet been revealed. The influence of the weekly regime of regulation of the Zhigulevskaya HPS, in which at the end of the working week, the fluctuation amplitude of many hydrological parameters probably decreases, is manifested in an increase in the abundance and biomass of planktonic ciliates at this time.The nature of the daily change in the average ciliates abundance in the water column was the same for a variant of the community in working days and was in antiphase with the change in the community abundance on weekends, namely: the maximum number on working days and on weekends was recorded in the evening (20.00) and in the daytime (14.00), respectively.

Habitat Preferences of Italian Freshwater Fish: A Systematic Review of Data Availability for Applications of the MesoHABSIM Model

The MesoHABitat SImulation Model (MesoHABSIM) is the preferred method to calculate spatio-temporal variation in the fish habitat availability in Italian rivers. With the aim of improving the applicability of the MesoHABSIM approach in the Italian territory, we carried out a systematic review of physical habitat preferences for 31 freshwater fish species and three freshwater lampreys, representing 75% of the total indigenous freshwater fish community of Italy. Information related to suitable ranges of depth, flow velocity, biotic/abiotic substrates, covers/shelters was collected and summarized for two critical life stages (adult and juvenile) and two bioperiods (rearing/growth and spawning). Overall, 250 publications were reviewed, classified as 206 peer-reviewed papers, 20 books, 7 PhD thesis, and 17 grey literature sources. Our analysis revealed substantial deficits of information about habitat requirements for more than 30% of Italian freshwater fish species. This information is particularly scarce for the most threatened endemic species, especially for their most critical bioperiod (i.e., spawning). With the aim of preserving freshwater fish biodiversity as required in the EU Biodiversity Strategy for 2030 (European Commission, 2020), accurate information on physical habitat requirements for spawning is crucial. As an example application of MesoHABSIM, the collected habitat preference information was used to define and apply mesohabitat suitability criteria for one fish species (Telestes muticellus) in a regulated river reach of Argentina Creek (Province of Imperia, Italy). This analysis demonstrates the potential for applying information from the current review to other fish species.