Permafrost in the Caspian Basin as a Possible Trigger of the Late Khvalynian Transgression: Testing Hypothesis Using a Hydrological Model

2021 ◽  
Vol 48 (6) ◽  
pp. 831-843
Author(s):  
A. N. Gelfan ◽  
A. S. Kalugin
Keyword(s):  
Hydrological Model ◽  
Testing Hypothesis ◽  
Caspian Basin

TO THE PROBLEM OF PRACTICABILITY OF CHANGING FISHERIES MEASURES FOR COMMERCIAL CATCHES OF ROACH AND SHEATFISHIN THE VOLGA-CASPIAN BASIN (THE ASTRAKHAN REGION)

2018 ◽  
pp. 7-13
Author(s):  
Vitaliy Victorovich Barabanov ◽  
Gennadij Grigor'evich Kolosyuk
Keyword(s):  
Retrospective Analysis ◽  
Caspian Basin ◽  
Commercial Catch ◽  
Reproductive Part ◽  
Fish Catch

Fisheries measures is an instrument allowing to regulate fish catch pressing to the aquatic bio-resources stocks. Roach and sheatfish are the species which are exploited in industrial and amateur fisheries of the Volga-Caspian basin (the Astrakhan region). According to the Fishery Regulations, today the minimum allowable length for roach is 17 centimeters, and for sheatfish it is 60 centimeters. According to the results of retrospective analysis of stocks dynamics, commercial catch of roach and cheatfish, experience in changing fisheries measures for roach and sheatfish in the Volga-Caspian basin, changing fisheries measures for these species has been found inexpedient. The current fisheries measures for commercial catch of roach allows to exploit only the reproductive part of the population, minimizing losses of restocking. Also, the work shows that a change of fisheries measures for sheatfish will lead to the decrease of the commercial catch of sheatfish and objects of its ration. In general, it must be stressed that changing fisheries measures will lead to redistribution of roach and sheatfish catches between the main participants (commercial fishers, amateur fishers and poachers), but not in favor of the official fish catching

Estimation of Regional Parameters in a Macro Scale Hydrological Model

2001 ◽  
Vol 32 (3) ◽  
pp. 161-180 ◽  
Author(s):  
Kolbjørn Engeland ◽  
Lars Gottschalk ◽  
Lena Tallaksen
Keyword(s):  
Additional Data ◽  
Hydrological Model ◽  
Sampling Methods ◽  
Probability Distributions ◽  
Repeated Application ◽  
Landscape Characteristics ◽  
Time Period ◽  
Macro Scale ◽  
Model Element ◽  
Regular Sampling

Macro-scale hydrological modelling implies a repeated application of a model within an area using regional parameters. These parameters are based on climate and landscape characteristics, and they are used to calculate the water balance in ungauged areas. The regional parameters ought to be robust and not too dependent of the catchment and time period used for calibration. The ECOMAG model is applied for the NOPEX-region as a macro-scale hydrological model distributed on a 2×2 km2 grid. Each model element is assigned parameters according to soil and vegetation classes. A Bayesian methodology is followed. An objective function describing the fit between observed and simulated values is used to describe the likelihood of the parameters. Using Baye's theorem these likelihoods are used to update the probability distributions of the parameters using additional data, being it either an additional year of streamflow or an additional streamflow station. Two sampling methods are used, regular sampling and Metropolis-Hastings sampling. The results show that regional parameters exist according to some predefined criteria. The probability distribution of the parameters shows a decreasing variance as data from new catchments are used for updating. A few parameters do, however, not exhibit this property, and they are therefore not suitable in a regional context.

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