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The relevance of the study is determined by the demand for a physically adequate mathematical description of the interactions of water in the soil to develop a model of soil moisture dynamics as the intellectual core of resource-saving technologies for precise irrigation farming. The aim of the work is theoretical substantiation and mathematical formulation of the hydrophysical functions of the soil, taking into account hysteresis. A description of three systems of soil hydrophysical functions is given. To verify and compare the systems, computational experiments were carried out using both the package of original software and “3305 Ida silt loam (> 15 cm)” soil data from the authoritative literary source – the Mualem catalogue. The parameters of the functions were identified by the method of point approximation of the experimental data on the main branches of the hysteretic water-retention capacity. Using these parameters, we calculated (i) predictive estimates for the values of the function of relative hydraulic conductivity; (ii) scanning branches of the hysteretic water-retention capacity; (iii) precise irrigation rate. The hysteresis phenomenon is not typical for the hydraulic conductivity as a function of the volumetric water content in the soil. The original functions of System 3 are recommended for use. The advantages of the proposed method for calculating the precise irrigation rate are shown. The benefit of each system is that the functions forming this system, namely the water-retention capacity and the relative hydraulic conductivity of the soil, have a common set of parameters. For the type of soil considered, in case of using the identical value of pre-irrigation soil moisture (179 [cm3 · cm-3]), both for calculating the precision irrigation rate and according to the “traditional” method, when moistening 50 cm soil layer, the total unproductive water consumption at irrigation rate 555 [m3 · ha-1] can reach 0.029 [cm3 · cm-3] or 140 [m3 · ha-1] in the calculated layer. At the same time, when applying precision standards, an excess of free moisture is not formed. It shows additional opportunities not only to save water during irrigation, especially in arid regions, but also to reduce the leaching of nutrients and agrochemicals outside the calculated soil layer and, accordingly, to reduce the additional environmental load on the surrounding area.

Data on soil moisture reserves are the basis for decision-making in the agricultural boghara system, because it determines the development of agricultural crops potential, terms of top-dressing and additional fertilizing, and makes it possible to predict yield of agricultural crops. In this article the influence of relief morphometric characteristics on the distribution of precipitation over the territory was studied. The research area is the land of the eastern part of Klepininsky rural settlement of Krasnogvardeysky district, the central part of Crimean Peninsula. The article considers approaches, divided into 2 main categories (according to the type of data used), based on the use of GIS capabilities and remote sensing data, to analyze the soil water content (SWC) using the example of research area and relationship of this parameter to the terrain relief. It was established that the morphometric characteristics of relief affect the amount of soil moisture.

Development of new offshore projects in the Arctic begins with comprehensive analysis of Marine Transport System’s (MTS) performance. At the same time researchers with different professional orientation (shipbuilders, logisticians, economists and managers etc.) are often have narrow view while making their investigations of MTS, focusing mostly at corresponding familiar sides of the system. It leads to specific “disproportional” description of MTS’s when some components considered in detail but other are out of investigation that in some cases may result in inaccurate conclusions. This makes authors sure that the only proper approach to investigate complex arctic MTS should be multidisciplinary. Article contains the description of integrated R&D project fulfilled at State Krylov Research Centre and devoted to realization of multidisciplinary methodology and corresponding software for arctic MTS design and analysis. Integrated software solution is based on object-oriented paradigm and combines such scientific areas as geographic information systems (GIS), shipbuilding disciplines, discrete event and agent-based simulation models. Theoretical base of the solution and its architecture envelops the following subject fields: ship design and fleet sizing, resistance and propulsion of ships including ice-going capabilities, vessel routing in ice, scheduling, downstream and upstream logistics, navigation process simulation, environment conditions stochastic modeling, operation research, queue theory, economy and management. Software has a modular structure with open and expansible architecture, which makes possible to add new functionality and upgrade existing program blocks in accordance with demands of specific project. Simulation model serve as the center of multidisciplinary integration because this technology allows reproducing behavior of different objects of MTS under dynamic conditions. Realized in AnyLogic ® framework simulation model replicates vessel operation process according to individual schedule generated by special planning component. Vessel’s activities simulated in modeled time with consideration of special aspects of operational planning and resolving accidents. Main model also includes specialized sub-models that provide opportunity to describe many local dynamic essences such as processes of offshore drilling and production, freeze-up of channel in fast ice, different ship interaction aspects, “weather windows” in ports etc. Number of instances are also given in the article, they allows to conclude that adequate and consistent model of MTS working in heavy ice-conditions or having complex organization scheme could be obtained only by means of simulation modeling under multidiscipline approach.

Three systems of functions are used to describe the water-retention capacity and the ratio of the hydraulic conductivity of the soil to the moisture filtration coefficient (relative hydraulic conductivity of the soil). Each of the three systems uses an appropriate set of parameters. These parameters are common to each pair of functions that make up the corresponding system. The parameters of the first system of functions are formal in nature and are used in the Mualem-Van Genuchten method. The parameters of the second and third systems have a physics-statistical interpretation. The main purpose of the considered systems is to predictively evaluate the values of the relative hydraulic conductivity function using parameters identified by the point approximation of data on the water-retention capacity of the soil. Using the soil example «3304 Touchet silt loam» from the Mualem catalog, three systems of functions are compared. In order to identify significant differences between the errors of the compared function systems with respect to the point approximation of data on water-retention capacity, as well as for predictive estimates of the values of the function of the relative hydraulic conductivity of the soil, the Williams-Kloot test is used. The influence of the additive parameter describing the capillary pressure of the «air inlet» on the errors of the second and third systems is estimated. The results of the study indicate the advantages of the second and third systems over the first system, the functions of which are used in the Mualem-Van Genuchten method. The third system is formulated in the form of fairly simple relationships using elementary mathematical functions and is recommended for modeling the hydrophysical properties of the soil and solving problems of ameliorative farming.

The most important of the hydrophysical properties is the water-retention capacity of the soil. This property is formulated as a relationship between the volumetric moisture of the soil and the capillary pressure of soil moisture. Three hysteresis models of soil water-retention capacity are presented. The parameters were identified by point approximation of experimental data (from an authoritative literary source) on the main (boundary) drying and wetting branches of the soil «2003 Silt of Nave-Yaar» using the «SoilHysteresis-v.1.0» computer program developed by the authors. Applying the condition of equality of the values of the exponential parameter for the branches of draining and moistening eliminates the undesirable (methodical) «pump effect». A comparative analysis of hysteresis models based on the identification of significant differences between the errors of the point approximation of the experimental data by the Williams-Kloot test. The advantages of models in which an additional additive parameter is used are revealed. The use of physically justified models of hysteresis of the water-retention capacity of the soil has prospects in the development and application of resource-saving technologies in precision reclamation agriculture.

A system of improved hydrophysical functions describing the water-retention capacity and hydraulic conductivity of the soil is presented. The mathematical description of the functions is based on the physical ideas about the structure of the pore space of the soil and the capillarity phenomenon. For both functions, the parameters are common. The advantages of the presented functions are described in comparison with the most well-known world analogues, which are used in the Mualem-Van Genuchten method. An example of estimation of the ratio of the hydraulic conductivity of a soil to the filtration coefficient of moisture according to the data on the water-retention capacity of a soil of sandy particle size distribution is given. The presented system of hydrophysical functions of the soil can be used to justify the development and resource-saving technologies in irrigation and drainage construction and irrigation agriculture. Practical application of applied models based on these functions will significantly reduce the energy intensity of the operation of irrigation and drainage systems and the production of agricultural products.

The improved method for estimating the effective supply of productive moisture in soil is based on soil-hydrological indices. The estimation is carried out using the software based on the mathematical model with physically interpreted parameters. The model is developed in the framework of the concepts of capillarity and lognormal distribution of effective pore radii and describes the main and scanning curves of the hysteresis of soil water-retention capacity. The presented example demonstrates the advantage of the improved method that enables minimizing water wastage at crop irrigation.

At substantiating land amelioration and land management designs, as well as during periods of operation and reconstruction of water facilities, information support plays an important role in relation to the hydrophysical properties of soil. Effective implementation of this support faces a number of challenges. Such problems include the very high laboriousness of carrying out the corresponding engineering surveys and laboratory studies. In this regard, the methods of indirect estimating the hydrophysical properties, the measurement of which requires considerable labor, are very in demand for land amelioration and land management practices. An equally acute problem is the problem of the functional representation of the coefficients of the Richards equation, which is widely used in engineering-hydrological calculations. The paper suggests: 1) the original method for assessment of the ratio of the values of the hydraulic conductivity function of soil to the moisture filtration coefficient using data from direct measurements of the water-retention capacity of soil carried out according to the standard procedure; 2) the mathematical model describing the hydrophysical properties of soil, and the system of functions with interpreted parameters that physically adequately describe the coefficients of the Richards equation. In carrying out the study, data on soils of different texture were used. A sufficiently low error in the dot approximation (fitting-procedure) of the experimental data confirms the physical adequacy of the proposed system that includes the functions describing the coefficients of the Richards equation.

A description of five mathematical models of the water-retention capacity of soil is given, taking into account the hysteresis phenomena. A computational experiment was carried out with these models using data on sandy soil. The experiment consisted of: (i) tuning of the models (parameter identification) by the method of dot-approximation of experimental data on the main drying and wetting branches of the hysteresis loop using an optimizing algorithm; (ii) the predictive calculation of the scanning branches of the hysteresis loop; (iii) a comparison of the errors in tuning results and the predictive calculation using the Williams-Kloot criteria. The commensurate and sufficiently low errors in the adjustment of the models have been achieved. The differences in the calculation of the scanning hysteresis branches are revealed. The practical significance of the mathematical models presented is to ensure the calculation of precision irrigation rates. The application of such rates in irrigation farming will help to prevent excess moisture from flowing beyond the root layer of the soil under the influence of gravity and, thus, to minimize the losses (unproductive consumption) of irrigation water, fertilizers, meliorants and plant protection products, and also reduce the risk of groundwater contamination with agrochemicals and eutrophication of water bodies.

Current intensification and changes in agricultural land use practices increase environmental impact that can be reduced by bridging the gap between socio-economic demands and scientific justification of sustainable agricultural land use. This can be achieved by replacing the goal of maximum crop yields with the goal of minimal environmental impact. This paper presents results of integrated crop simulation system development for analysis of alternative planning strategies in agricultural land use, with focus on the crop rotation influence on environmental sustainability. The effective tools used in analysis include (1) long-term analysis of changes in agricultural land using a dynamic crop model with daily time step; (2) justification of arbitrary crop rotation scheme of different agro-technologies and sparing measures; and (3) analysis of modern farming management methods using model-oriented approach. The results of study also include estimation of two alternative practices of crop harvesting including remaining or removing whole crop residues from the agricultural field and their influence on basic parameters of soil fertility. In addition, we analyzed comparative efficiency of different agricultural measures neglecting the negative influence of possible climate changes in long-term consequences. Corresponding efficiency rating is the following: organic fertilizer, green manure legume sparing harvesting, winter catch crop, and rotation scheme.

Basic principles of the multidisciplinary approach to arctic marine transport systems (MTS) design and analysis are described in the article. The main idea of the approach is to synthesize geographic information system (GIS) technologies, different shipbuilding disciplines, fleet planning instruments and agent-based dynamic simulation models in an integrated software framework on the basis of object-oriented programming. Vessel operation is described as the movement and interaction of independent ships in GIS environment within the framework of the simulation model. MTS operation combines vessel operation itself (routing, determination of speed and fuel consumption, icebreaker escort, etc.) with plenty of external entities (port infrastructure, ice channel freezing process, offshore platform operation, etc.) that could be described as systems with comprehensive logic and physical behavior. Such integration provides a new quality of MTS simulation that allows considering complex interconnection of various subsystems and all the important details of each MTS project. The outline of the program framework to realize such an approach is given, and two case studies are described to demonstrate its capabilities and feasibility.

A functional description of the hydrophysical properties of the soil as a capillary-porous medium is presented. The described functions of water retention capacity and hydraulic conductivity of the soil have common parameters, which are interpreted within the framework of physical and statistical concepts. The practical significance of the proposed functions lies in the fact that the volume of labor-intensive field measurements necessary, for example, for modeling the dynamics of soil moisture, is significantly reduced. To identify the parameters of these functions, it is sufficient to use data only on the water retention capacity of the soil. The parameters identified in this way can be used to predict the ratio of the hydraulic conductivity of the soil to the moisture filtration coefficient. The presented system of the hydrophysical functions of the soil is compared with world analogues using literature data on soils of different texture.

A method is proposed to calculate water irrigation rates for crops that considers hysteresis in the volumetric water content (θ)-water pressure head (ψ) relations, including scanning paths, by the method of point approximation. Three θ(ψ) models are described and computational experiments were carried out using data from literary sources on the hydrophysical properties of soils with different textures. The error analysis of the point approximation of the main branches and the predictive calculation of the scanning branches of the hysteresis loop were carried out. The practical significance of the research lies in the possibility to calculate the precise irrigation rates for crops. The use of such standards minimizes unproductive spending of irrigation water, fertilizers, ameliorants and plant protection products, as well as prevents the pollution of natural waters with agrochemicals and reduces the risk of eutrophication of water sources.

An original and convenient (from a practical point of view) method to estimate the supply of productive moisture in the soil is offered. The method is based on a physically adequate mathematical model of the soil hydrological properties considering the hysteresis of the water-retention capacity. The computation of the irrigation rates, which is based on such estimates, minimizes the water wastage if the excess of the gravitational water is formed and this water percolates out of the moisturized soil profile under watering conditions. The practical applying of the method is able to optimize the crop irrigation techniques, eliminates any inefficient losses of irrigation water and nutrients (and other agricultural chemicals), promotes the rational usage of the water resources as well as provides developing effective solutions of urgent problems of the land ecological management.

Climate change is expected to alter a multitude of factors important to agricultural systems, including pests, diseases, weeds, extreme climate events, water resources, soil degradation, and socio-economic pressures. Changes to carbon dioxide concentration ([CO2]), temperature, andwater (CTW) will be the primary drivers of change in crop growth and agricultural systems. Therefore, establishing the CTW-change sensitivity of crop yields is an urgent research need and warrants diverse methods of investigation. Crop models provide a biophysical, process-based tool to investigate crop responses across varying environmental conditions and farm management techniques, and have been applied in climate impact assessment by using a variety of methods (White et al., 2011, and references therein). However, there is a significant amount of divergence between various crop models’ responses to CTW changes (R¨otter et al., 2011). While the application of a site-based crop model is relatively simple, the coordination of such agricultural impact assessments on larger scales requires consistent and timely contributions from a large number of crop modelers, each time a new global climate model (GCM) scenario or downscaling technique is created. A coordinated, global effort to rapidly examine CTW sensitivity across multiple crops, crop models, and sites is needed to aid model development and enhance the assessment of climate impacts (Deser et al., 2012)...

A mathematical model of the hysteresis of the water-retention capacity of the soil is proposed. The parameters of the model are interpreted within the framework of physical concepts of the structure and capillary properties of soil pores. On the basis of the model, a computer program with an interface that allows for dialogue with the user is developed. The program has some of options: visualization of experimental data; identification of the model parameters with use of measured data by means of an optimizing algorithm; graphical presentation of the hysteresis loop with application of the assigned parameters. Using the program, computational experiments were carried out, which consisted in verifying the identifiability of the model parameters from data on the main branches, and also in testing the ability to predict the scanning branches of the hysteresis loop. For the experiments, literature data on two sandy soils were used. The absence of an "artificial pump effect" is proved. A sufficiently high accuracy of the prediction of the scanning branches of the hysteresis loop has been achieved in comparison with the three models of the precursors. The practical importance of the proposed model and computer program, which is developed on its basis, is to ensure the calculation of precision irrigation rates. The application of such rates in irrigation farming will help to prevent excess moisture from flowing beyond the root layer of the soil and, thus, minimize the unproductive loss of irrigation water and agrochemicals, as well as reduce the risk of groundwater contamination and natural water eutrophication.

A method for nonlinear approximation of stochastic processes is derived for calculation of climatic trends of long-term meteorological data sets. The method mainly makes use of spline approximation, Green's function and spectral transfer function of the Chauchy problem. Generally applicable for a wider range of problems the method is specified for special conditions typical for meteorological and climatological data. The applicability of the method described is examined on the basis of long-term (40... 228 years) meteorological data sets for temperature and precipitation data from one Australian and five European locations. The results obtained are discussed in comparison with climate trend results from temperature and precipitation data taken from literature.