On the example of the estuary irrigation system «Bolshaya Polyana» of the Verkhoyansk region, the current state of reclaimed lands in the Arctic zone of Yakutia in a changing climate is considered. Research methods included reconnaissance and topographic surveys of the study area, analysis and processing of research materials previously obtained by the author. An analysis of natural and climatic conditions showed that due to climate change, there is a reduction in the cold winter period, catastrophic amounts of winter precipitation, abnormal heat in summer periods and an increase in the average annual temperature over the past 15 years by 1.2°C, which affected the shift in the start date of irrigation of estuary meadows for early periods up to 9 days. The heterogeneity of the relief of estuary meadows and the overgrowth (cluttering) of irrigation canals were revealed, in connection with which the irrigation period reaches 25-30 days, as a result of which waterlogging of the soil occurs. Agrochemical studies determined the type of soils, frozen peat-gley soil in the hay area of estuary irrigation and frozen humus-gley soil in the natural area. Measurements of the seasonal thaw layer in the natural area show deeper thawing of soils than in the hay fields of the estuary irrigation system. Also, measurements at different flood depths show that the greater the flood depth, the smaller the thawing layer. These phenomena, in our opinion, are due to the type of soils and may be associated with the influence of the layer of irrigated waters on the thawing of soils. The results of the studies carried out require further measures and studies to create an optimal irrigation regime, improve the water-physical properties of soils, for which it is proposed to improve irrigation methods by building a double-regulation reclamation network and subsequent study of its effect on the thermal and moisture conditions of irrigated haylands and agrochemical indicators of soils.

The purpose of the study is to improve the design of the installation through the use of soil moisture concentration sensors and digital LCR meter XJW01. The digitalization of hydrotechnical melioration of agricultural lands in the Russian Federation requires the active use of mathematical models for the movement of moisture flows, nutrients, air, and heat in the soil profile. The parameters of these flows in the laboratory are determined by the methods of physical modeling. Improving the design of installations for the physical modeling of soil processes increases the accuracy of measurements and reduces the labor intensity of work. The modernized facility for physical modeling of saline soil leaching includes electrical sensors for measuring the concentration of soil moisture. The sensors are equipped with conductive plates and conductive windings. Digital LCR meter XJW01 automatically detects the sensor as an electrical oscillatory circuit and fixes its quality factor. The quality factor of the sensor depends on the concentration of soil moisture that fills its body. The operating prototype of the installation was tested. In the concentration range of NaHCO₃ solution from 0 to 350 mmol/dm³, the quality factor of the sensors varies from 282±2.1 to 221±2.7 (significance level P = 0.99, number of degrees of freedom k = 4, and Student’s test t = 4.60).

Based on the results of the research, a methodology for calculating the irrigation rate was compiled, taking into account the parameters of the moistening circuit, the characteristics of soil conditions and the general mineralization of irrigation water. Hydrocarbonate calcium waters predominate in the Central region, the total mineralization varies widely depending on the time of year and the type of water source. It is proved that this parameter affects the nature and rate of formation of the irrigation contour. The technique was tested at the experimental site of the Field Experimental Station of the RGAU-MAA named after C.A Timiryazev when growing early ripe potatoes of the «Udacha» variety. Irrigation water savings amounted to 16%. The application of the proposed method for calculating the irrigation rate, taking into account the shape of the moisture contour and its geometric parameters, depending on soil conditions and mineralization of irrigation water, will fully reveal the advantages of drip irrigation in saving irrigation water and preventing its filtration into deep soil layers.

The methods of manufacturing test placers and compositions for visual-blister colorimetric determination of concentrations of phosphate ions and sulfite ions for their quantitative determination in soils and water bodies have been optimized. The test placer contains all the reagents for the analytical reaction. Placers allow the quantitative determination of phosphates and sulfides in aqueous samples without prior preparation of reagent solutions. In a blister cell with a diameter of 6 mm, a much more intense color was achieved with a solution layer of no more than 2 mm. The application of reagents to the surface of homogenized and discolored hemp awns avoids their contact until the chemical analytical reaction takes place. The composition of placers and the conditions for applying reagents are optimized. Sufficiently high acidity can be provided by hydrosulfate ions with the addition of a few drops of solution. The reaction proceeds in the volume of the added test solution, which is 2-3 drops.

The present study assesses the efficiency of using artificial roughness as a flow energy dissipater on the spillway of a low-head concrete spillway. A comparative analysis of the effect of different types of roughness elements in the downstream is presented. Separately, the elements of resistance in the form of bottom ribs lying horizontally at the bottom of the waterfall, as well as vertically standing elements of resistance (cubes, cylinders, concrete blocks, hemispheres) are considered. The influence of the shape of the elements, their location and their distribution density per unit area is evaluated. Among the ribbed elements of roughness studied, the most promising is the double zigzag against the current. Among the vertically standing elements, it is advisable to give preference to elements with sharp edges (cubes, blocks, plates). Most of the works devoted to the study of artificial roughness is based on experiments conducted in natural or artificial channels with relatively small slopes compared to the spillway face of practical profile spillways, as well as steeply falling sections of fast currents with slopes of i>0.3. An assessment of the efficiency of the bottom ribbed elements on the model of a low- and medium-pressure concrete dam is proposed to identify the most effective structures in relation to the resistance elements often used in practice at fast currents.

Assessment of the susceptibility of concrete to cracking with subsequent changes in the volume and nature of pores, as well as capillary passages, deformation and strength properties of the material (especially tensile deformations and tensile strength) are the main indicators by which the resistance and durability of linings of water channels can be predicted. By regulating technological factors, it is possible to significantly reduce the intensity of moisture shrinkage, which in turn makes it possible to achieve an increase in the operational reliability and durability of concrete linings. The main reason for the manifestation of shrinkage cracks in concrete is the excess, at a certain point in time, of non-manifested shrinkage deformations, as a result of which tensile stresses are formed in the material with constrained shrinkage, the ultimate tensile strength of concrete. Qualitative prediction of the potential resistance and durability of linings of water channels is possible when assessing the predisposition of concrete to cracking with subsequent changes in the volume, nature of pores and capillary passages, deformation and strength properties of the lining material.

The results of the study on the analysis, generalization and forecast of changes in the average annual and seasonal volumes (flows) of the Volga River to Volgograd (the formation zone) are presented. For the forecast, time flow series are used for the periods 1881/1882-2020/2021, N-140 years and 1914/1915/2020/2021, N-107 years. These periods are accepted as the basic periods characterizing the formation of the Volga River flow to Volgograd. It is revealed that the long-term fluctuations of the Volga River flow contain three periods, the first series, two periods, the second series, significantly differing in average annual values. It is established that these periods under consideration are characterized, along with statistical long-term averages, by dynamic ones, which are functions in time. Also, the multidirectional trend (trends) in the considered flow time series are revealed. Functional equations for the identified trends for these periods are obtained. Thus, the presence of cycles and trends, in the long-term fluctuations of annual and seasonal values of river water inflow, as well as functional equations serve as the scientific basis for their prediction for certain periods of time in the future, including the first half of the XXI century. The analysis based on sufficiently long time series of the river Volga to Volgograd shows that in the future there is a high probability of manifestation of different intensity of annual and seasonal flow due to its characteristic cyclical fluctuations. Confirmation of this, in particular, is the identification of changes in the nature of the trend of annual fluctuations in the flow of the Volga River in Volgograd.

Development of effective fish protection measures at water intakes is one of the main directions of fish resources conservation and reproduction in inland water bodies of the country. Its complexity is associated with the involvement of many related disciplines: ichthyology, physiology, hydrobiology, ecology, hydraulics, hydrology, etc. In the process of solving the problem of standardization of information to be used for creating mathematical models for forecasting potential impact of water intakes with fish protection on aquatic ecosystem. The article gives a review of the research on the technology of aquatic bioresources (ABR) conservation, conducted by JSC «Institute Hydroproject» (Moscow) together with LLC «Hydrotechnika» (Sochi), the basic provisions of modeling methodology are considered; the results of mathematical modeling of currents in the upstream in the area of hydraulic units, spillways and rockfill dam at Boguchanskaya HPP; results of experimental studies of stream generators and biohydraulic modeling. The assessment of the conducted research is given.

In the channels of mountain and foothill streams, as a result of landslides (collapses) of coastal slopes, litter soil dams are often formed, blocking the watercourse channel. On the upper side of them, water masses accumulate, the overflow of which through the dam can lead to the destruction of the latter and the emergence of a catastrophic breakthrough mudflow that threatens the safety of life of the lower territories. In these conditions, it is important to quickly assess the extent of the risk, taking into account the existing hydrogeomorphological characteristics of the channel reservoir. The paper obtains calculated dependencies for the analytical finding of the necessary characteristics of the (full, partially filled) flood reservoir, as well as the values of the reserve volume and time of filling the reservoir, based on remotely determined parameters of individual points located on the dam and the adjacent channel of the watercourse.

The purpose of the work is to analyze the problems and prospects of water management in the Lam River basin (Vietnam), as well as their impact on water use conditions in the provinces - Nge An and Ha Tinh. The analysis takes into account the development of irrigation, hydropower and the main trends in water management. The efficiency of water use in the Lam River basin was assessed, planning, management structure and sources of financing for water management were analyzed, as well as prospects for the development of hydropower and irrigated agriculture were considered. Up-to-date data has been collected, and the structure of water use for the river basin of the Lam River has been compiled. Recommendations on planning and management of water resources have been developed. The research applied a comprehensive integrated approach, the method of system analysis and the provisions of the concept of sustainable development, methods of expert assessments. The analysis of water use, taking into account the state of hydro-reclamation systems operation in the Lam River basin, showed that the operational capacity of irrigation facilities does not meet the requirements; water loss during irrigation is about 30%, in the household water supply losses are 25.5%. There is no master plan for the use of water sources; there is no plan and financing to replace old reservoirs and ponds for irrigation purposes. The survey of experts and the public also revealed the problem of insufficient accumulation and exchange of relevant information on the river. Management, operation and use, as well as planning of water resources in the Lam River basin have made positive changes, having a certain impact on the community. However, in order to successfully implement the transformation of water resources management from traditional to integrated, it is required that the communities in the basin overcome the shortcomings in the exploitation and use of water resources.

The objective of the study is to examine and forecast the possible volumes of timber harvesting in the near future in the Far East of Russia on the example of the Khabarovsk and Primorsky territries, based on the actual volume of logging over the past eight years. The methods of comparative and computation al analyses were used as methodological basis of the study, including the collection and analysis of logging and processing industries information. Industry and customs statistics, as well as the authors’ own research, were taken as initial data. The current situation with timber harvesting in the Far East is directly related to inefficient logging planning and the lack of effective control over forest users. According to our assessment, the volume of timber harvesting will gradually decrease and by 2025 will not exceed 3.0 million m³ in the Primorsky territory and 5.0 million m³ in the Khabarovsk Region. However, wood processing will grow significantly and will reach 80% of the total volume of harvested wood. Hardwood will serve as an exception, the harvesting of which will not exceed 300 thousand m³, and processing will achieve almost 100%.

The article presents observational data on the survival, preservation and growth of introduced tree species created in the interstrip spaces of the green zone of the city of Nur-Sultan. The greatest preservation is characterized by Siberian spruce (Piceaobovata Ledeb.) (76.8%) and blue spruce (Piceapungens Engelm.) (58,9%). Black spruce (Piceamariana Mill.) and Siberian larch (Larixsibirica Ledeb.) have a preservation rate of an average of 44.5%. The lowest survival rate and preservation (16.4%) is distinguished by Siberian fir (Abiessibirica Ledeb.). When comparing the method of planting forest crops with planting the material with an open and closed root system, it was revealed that the survival ability and preservation of seedlings with ORS was slightly higher than that of seedlings with CRS. The average survival ability of seedlings with ORS was 58.1%, for seedlings with CRS -53.7%. Plants height corresponds to the biological characteristics of woody species. The highest average height was for Piceamariana Mill (184.1 cm), the smallest average height was for Piceaengelmannii Parry ex Engelm (143.4 cm). The most acclimatized species of woody plants - Piceaobovata Ledeb., Piceapungens Engelm. and Piceamariana Mill - have been identified. These trees have a high capacity for survival, stable growth and decorative effect. These coniferous plants can be used to create green areas of settlements in Kazakhstan, similar in soil and climatic conditions to the city of Nur-Sultan.

The main purpose of the research is to determine the sanitary and forest pathological state of the entire tree stand of the main forest areas located on the territory of the municipal formation of the city of Stavropol, located in the forest-steppe zone. The relevance for the ecology of a large city of forests, both natural and artificial origin, is considered. The characteristics of the forest, its origin and qualitative condition are given. The studies used standard methods of forest taxation and forest pathology survey with appropriate cameral treatment, namely, selective ground observations. An accelerated fall off of petiole oak, Caucasian hornbeam, and common ash was revealed. The main conclusion of the study is that in order to improve the tree stand, it is necessary to carry out sanitary and recreational measures in the form of selective sanitary cutting and harvesting of illiquid wood, as well as detailed observations of the pest population.