Runoff Formation Model for the Amur River Basin

ECOMAG software complex was adapted to simulate river runoff in the Amur basin using data from global databases (relief, soils, landscapes). The results of model calibration and verification were used to give a statistical estimate of the efficiency of river runoff calculation over a long period based on standard data of meteorological and water management monitoring. The results of calculations using the developed runoff formation model were used in the space and time analysis of the formation conditions of 2013 flood in the Amur basin.     

Runoff of Russian Rivers under Current and Projected Climate Change: a Review 2. Climate Change Impact on the Water Regime of Russian Rivers in the XXI Century

Water Resources - The present overview is the second part of the article “Runoff of Russian Rivers Under Current and Projected Climate Change: A Review,” which focuses on modern...     

Assessing the Sensitivity of a Model of Runoff Formation in the Ussuri River Basin

A physically based model of runoff formation with daily resolution has been developed for the upper part of the Ussuri basin with an area of 24400 km² based on ECOMAG hydrological modeling platform. Two versions of the hydrological model have been studied: (1) a crude version with the spatial schematization of the drainage area and river network based on DEM 1 × 1 km with the use of soil and landscape maps at a scale of 1: 2500000 and (2) a detailed version with DEM 80 × 80 m and soil and landscape maps of the scale of 1: 100000. Each version of the model has been tested for two variants of meteorological inputs: (1) meteorological forcing data (temperature, air humidity, precipitation) at eight weather stations and (2) with the involvement of additional data on precipitation collected at 15 gages in the basin. The model has been calibrated and validated over a 34-year period (1979–2012) with the use of runoff data for the Ussuri R. and its tributaries. The results of numerical experiments for assessing the sensitivity of model hydrological response to the spatial resolution of land surface characteristics and the density of precipitation gaging stations are discussed.     

Spatial and Temporal Variations in the Formation of the Kamennaya Steppe Water Regime

The processes of water regime formation in the catchment areas of deans in the Kamennaya Steppe are studied based on the data of many-year field experiments. Certain regular variations are recognized in the characteristics of the Kamennaya Steppe hydrological and ecological condition and their correlation with anthropogenic and climatic factors is established.     

Natural and Human-Induced Variations in Water and Sediment Runoff in the Danube River Mouth

Long-term natural and human-induced variations in water and sediment runoff in the Danube Delta head were studied on the basis of analysis of an extremely long series of observations (1840–2002). A considerable reduction of sediment runoff in the second half of the 20th century related to sediment accumulation in reservoirs was revealed. It was found that human activities had an insignificant impact on the water runoff variations and the period of 1961–2002 turned out to be abnormally water-abundant.     

Space and Time Variations of the Concentrations of Dissolved Forms of Microelements in Amur River Water

Water Resources - The results of studies of water bodies in the Amur R. basin in 2011–2017 have been used to characterize the space and time variations of the concentrations of dissolved...     

Scenario-Based Forecasts of Changes in the Temperature and Hydrological Regime of Crimea in the XXI Century by Data of CMIP6 Climate Models

Water Resources - Scenario projections of climate changes in the XXI century in Crimea are presented based on the data of an ensemble of models of the recent generation CMIP6 for aggressive SSP585...     

Sensitivity Assessment of a Runoff Formation Model in the Mozhaisk Reservoir River Basin

Water Resources - The physically based model of river runoff formation with a daily resolution ECOMAG was adapted for the Mozhaisk Reservoir with an area of 1360 km2. A large series of numerical...     

Scenario Projections of Changes in Snow Water Equivalent Due to Possible Climate Changes in Different Regions of the Earth

Water Resources - The study was carried out under the international Earth System Model–Snow Model Intercomparison Project on ten experimental well-instrumented snow sites in different parts...     

Projecting Changes in Russian Northern River Runoff due to Possible Climate Change during the 21st Century: A Case Study of the Northern Dvina,Taz and Indigirka Rivers

Water Resources - Projected changes in river runoff due to possible climate change during the 21st century were simulated with making use of a physically-based land surface model SWAP and...     

The Contribution of Glacial Melt Water to Annual Runoff of River Volga in the Last Glacial Epoch

Water Resources - The runoff of glacial melt water into the river system of the Volga and farther into the Caspian Sea is evaluated for the epoch of the last glaciation. Melt water entered the...     

Variations of the Present-Day Annual and Seasonal Runoff in the Far East and Siberia with the Use of Regional Hydrological and Global Climate Models

A method of spatial calibration and verification of regional numerical physically based models of river runoff formation, incorporating runoff formation processes in the main river channel and its tributaries, was used to obtain a statistical estimate of the quality of river runoff calculation by conventional and alternative criteria focused on runoff reproduction in different phases of water regime and the characteristics of its variations. The analysis of the simulation quality of the annual and mean monthly river runoff (average runoff, standard deviation, and the coefficient of variation) at the near-mouth gages over the historical period with boundary conditions represented by data of global climate models showed the results to be satisfactory. This allows the proposed combination of climate and hydrological models to be used to study physically based regional variations of water regime under different physiographic and climatic conditions in the examined river basins with flood runoff regime (the Amur R.) and the predominant snowmelt runoff during spring flood (the Lena R.).     

Two Experimental Methods to Determine the Speciation of Cadmium in Sediment from the River Neckar

The binding forms of Cd to an anaerobic sediment of low sulfide content from Lauffen reservoir (River Neckar, Germany) were studied using two different approaches, i. e. sequential extraction (modified from published protocols) and titrimetric study of the pH-dependent Cd release. Thermodynamic equilibrium calculations were applied to calculate both the release pattern of Cd during the titrations and the speciation of Cd within the single fractions of the extraction protocol. The calculations were based on measured sediment parameters such as hydrous ferric oxide (HFO), acid volatile sulfide, carbonate content and total Cd content, and the extractants (oxalate, acid etc.) used. The results of the two independent approaches coincided well in that they both assigned more than two thirds of the total Cd content to be adsorbed to organic matter. Cd bound as CdS is of little importance. Sequential extraction after a 3-month oxidation period at pH 7 revealed a shift of Cd from being mainly bound in stronger surface complexes with organic matter to being mainly bound in weaker surface complexes with organic matter and HFO, and thus becoming more bioavailable. This study suggests that the use of sequential extraction although being frequently criticized due to its operational character can be used to determine binding forms of metal ions if they are accompanied by 1) careful supporting experiments, 2) analysis of important sediment parameters, and 3) the use of thermodynamic equlibrium models which can help to understand Cd speciation within the extraction fractions.     

Species Composition and Seasonal Variations of the Gastropoda in Upper Sakarya River System (Turkey) in Relation to Water Quality

Species composition, abundance, and seasonal distribution of the Gastropoda fauna and the physical and chemical variables of Upper Sakarya River System have been investigated between October 1998 and August 1999. Gastropod fauna in the Upper Sakarya River System was represented by 9 species of Prosobranchia and 7 species of Pulmonata. Diversity, dominance, and abundance of the Gastropoda species were recorded seasonally. The abundance of some of the 16 species was correlated positively with temperature, dissolved oxygen and negatively or positively with pH and nitrate. It was observed that Gyraulus albus (Müller, 1774), Physa acuta Draparnaud, 1805, Valvata pulchella Studer, 1820, and Oxyloma elegans (Risso, 1826) can tolerate a high level of NO‐N while V. piscinalis (Müller, 1774) spread out in unpolluted water. Although the species and their numbers change at the stations, the maximum numbers were found during autumn, while minimums were identified during the winter sampling. Gyraulus albus was the most widespread species in our research area. Only 5 species (Gyraulus albus, Physa acuta, Valvata cristata (Muller, 1774), Valvata pulchella, Melanopsis praemorsa costata (Olivier, 1804)) were determined each season. However, no Gastropoda were found at the station 3 that has high BOD, NO‐N, NO‐N, and NH₃ levels.     

Observations on the Bottom Fauna of the Ganga River (between Buxar and Ballia) with Special Reference to Its Role in the Seasonal Abundance of Fresh Water Prawn Macrobrachium birmanicum choprai (Tiwari)

The paper deals with the changes in composition and density of bottom fauna of the Ganga river at Buxar and Ballia in relation to soil texture and water quality observed between March 1984 and Feb. 1986 with its possible role in the seasonal abundance of M. birmanicum choprai. No marked differences were noted in the quality of water at the two centres. The texture of bottom was sandy at both the centres, but the soil at Ballia was found to consist almost of sand with a negligible quantity of clay content. The benthic fauna mainly consisted of dipterans, amphipods and annelids and exhibited a higher abundance at Buxar. It showed a major pulse in the month of March with a minor one in December. The macrobenthos including gastropods and bivalves were abundant during summer (March–June). The bottom fauna on which the prawns generally feed becomes a potential source of food during winter when the prawns get confined to a unit area.