Том 45, № 4 (2018)

A method is proposed for incorporating possible global changes in the state of the atmosphere, basing on K. Hasselmann’s theory of stochastic climate models, for assessing the significance of forecasts of variations of annual river runoff depth in the XXI century. The data used includes the results of river runoff simulation at warming, obtained using 21 IPCC climate models along with six IPCC scenarios of greenhouse gas emission, and MEI scenario. The significance index of forecasted runoff variations, i.e., the values of runoff depth increments divided by the standard error of forecasts was mapped. To demonstrate the role of the maps of significance index, which have been constructed taking into account forecast uncertainty because of the natural changes in global climate, those maps were compared with the maps of significance index calculated basing on other sources of errors. At large time scales, the uncertainty of runoff forecasts owing to natural changes in global climate plays the main role in assessing the reliability of forecasts in areas where greenhouse effect is strongest. Estimates of the significance index show that statistically significant changes in the annual runoff depth in the extreme northeast of Eurasia can be expected to occur not earlier than the late XXI century. In other RF regions, as well as in the majority of world areas, the forecasted changes in the annual runoff depth are comparable with the standard errors of the respective estimates or are less than they are.

The study is focused on the specific features of water resources formation in Eastern Siberia under variable climate and regional occurrence of permafrost rocks. Expert estimates are given to the effect of greenhouse gas emissions on climate evolution in this large region. Under present-day climate conditions, featuring temperature rise and some increase in precipitation as resource-forming factors, the most significant changes are shown to have taken place in the formation of water resources and regime of dry-season runoff in individual rivers of Eastern Siberia, including the Lena, Indigirka, Kolyma, etc. Present-day resources of surface water and groundwater resources in the region are mapped and the dynamics of the annual and dryseason runoff of the rivers are plotted.

Sediment yield of Kamchatka Krai rivers into the Pacific Ocean and the seas of Bering and Okhotsk, is evaluated, including that from the drainage basins that are not covered by regular observations. Regression dependences of specific suspended sediment yield (SSSY) on factors determining it were constructed for erosion regions identified in Kamchatka Krai. The total average many-year yield of suspended sediments of Kamchatka Krai rivers into the Pacific is 11.4 × 10⁶ t/year, 73.9% of which is transported by rivers of the eastern coast and 26.1%, by those of the western coast. Among other factors, such distribution is attributed to the location of the majority of volcanoes on Kamchatka eastern coast. About one third of all sediments transported from Kamchatka Krai territory is discharged by the two largest rivers in the region, i.e., the Penzhina and Kamchatka.

An explanation is given to the fact that the cumulative number of damage cases is a decreasing function of the form Y^−2/3. This is because the inundated area S depends on precipitation volume V as S ~ V^2/3. Such dependence is confirmed by the data on the area of mushroom-shaped plumes at river mouths in the sites of river influx into the ocean.

The aim of this study was to transform the rain into flow in the basin of Wadi Djendjen by using a simulation model in absence of the continuous measurements of the flow. The obtained results indicated and confirmed the strong adaptability of this model with varied hydroclimatic situations. The validation process showed an interesting result, which lead to conclude that the model is well calibrated and has a good performance to be used for the basins with Mediterranean climate. The obtained results for the simulation by the GR2M model over the studied period (1973–1986) showed that there no significant difference between the obtained value for the yearly average flow (197.70 hm³) and that measured at Missa hydrometric station (200.80 hm³), which allow us to estimate quantitatively the flow in Missa hydrometric station. While, for the period of 2000–2012, the results showed that the yearly average flow value (171.90 hm³), is significantly different (reduction of 15% for 12 years), in comparison with that measured at Missa hydrometric station (200.80 hm³). This can be due to the dryness which struck the region since 2000, and the local degradation of the forest ecosystem, which has considerably affected the runoff surface.

The analysis of hydrogeological problems arising in bog watering by methods enabling the depth to groundwater table to be controlled was used to develop a method for estimating the efficiency of such control when data for directly solving groundwater flow problems are lacking. The effect of nonmonotone dependence of the rate of groundwater level rise on the hydraulic conductivity of peat underlain by high-permeability sand rocks is described. This effect is shown to be significant in assessing the potentialities of the operational control of groundwater level in bog massifs with this type of geological structure.

The impact of tidal wave on a permeable shore consisting of porous material results in groundwater table lying above the average sea level. This effect, stemming from the nonlinearity of the process of seawater flow in the soil, is referred to as pumping effect.

Channel expansions are common in both natural and artificial open channels. With increasing cross-sectional dimensions in an expansion, the flow decelerates. Due to separation of flow and subsequent eddy formation, a significant head loss is occurred along the transition. This study presents the results of experimental investigations on subcritical flow along the expansive transition of rectangular to trapezoidal channels. Also, a numerical simulation was developed using the finite volume method with Reynolds Stress turbulent model. Water surface profiles and velocity distributions of flow through the transition were measured experimentally and compared with the numerical results. Also, hydraulic efficiency of the transition and coefficient of energy head loss were calculated. The results show that with increasing the upstream Froude number, hydraulic efficiency of the transition and coefficient of energy head loss are decreased and increased, respectively. The results also showed the ability of numerical simulation for simulating the flow separation zones and bed shear stress along the transition for different inlet discharges and inflow Froude numbers.

Development features of anthropogenic processes in continental waters in the Arctic Basin, including eutrophication, acidification, and toxic pollution, are characterized. The major changes in the ecosystems and the formation periods of hazardous situations are demonstrated. Criteria are suggested for the diagnostics of unfavorable processes and the need of more stringent water quality standards is substantiated.

Data on diatom complexes from bottom deposits of Lake Karakel’ (the Karachayevo-Cherkessian Republic) have been analyzed. The principle of unification of bioindication methods has been applied. The hydrological parameters of lake water (temperature, pH, and saprobithy) have been reconstructed over a period of 2000 years. The results of isotopic dating of bottom sediments have been used. For the first time for the Central Caucasus, the current and Late Holocene diatom alga complexes have been described. Photographs of the most abundant and significant lower taxa of diatom algae are given.

We examined the land use impact on the water quality of small water bodies located in northern Poland. Twenty nine ponds, located in the urban area or a typical agricultural land were analyzed based on physical-chemical parameters: water temperature, conductivity, oxygen concentration, content of particulate suspended matter and chlorophyll “a”, and nutrients concentration. Additionally, to describe and compare the trophic condition of investigated small water bodies, we used the Carlson type trophic state. Performed measurements showed that nutrient concentrations significantly differentiated the agricultural ponds from urban water bodies. Mean total phosphorus and nitrogen concentration in midfield ponds were about 5 and 3 times higher, respectively, than in urban ponds. Moreover the phytoplankton chlorophyll “a” mean values were on average fivefold higher in agricultural ponds. Furthermore, urban ponds were characterized by lower values of TSI, thus lower trophy level: generally on the border of meso- and eutrophy. The agricultural ponds trophy changed from meso- to hypertrophy.

In agriculture, water is a fundamental but increasingly scarce resource that requires careful use. The goal of fostering water-savings could be achieved with a regulation that imposes more efficient irrigation systems. This might represent the only policy option when water withdrawals cannot be controlled and when the operational context does not allow filling the information asymmetry between policy makers and farmers with metering systems, quotas, or market rights. The regulation could involve higher costs for farmers. However, it could represent an opportunity to increase farm revenues if consumers are willing to pay a higher price for goods produced according to an ecological standard. Knowledge of the costs and possible benefits is relevant because it would enable us to understand the potential cost allocation among stakeholders according to how the policy is designed. The results of this study indicate that the management cost of a sustainable irrigation system could be at most 48% greater than that of a wasteful, traditional system. However, the higher costs of the regulation could be compensated for because consumers are willing to pay 6.8% more for less intensive water-use agricultural products. Therefore, a regulation associated with the promotion of hypothetical water-saving label can be the best strategy to irrigation efficiency in agriculture.