The necessity and scientific and methodological approaches to improving the calculation of a closed collector-drainage network of drainage systems are considered. Based on the application of the system methodology, the structure of the hierarchical and hydraulic connection between the water regime of the field and the operation mode of the closed collector-drainage network has been established. On the basis of the theoretical and experimental studies performed, relatively new scientific provisions have been proposed. This will allow, based on the application of the obtained universal equations, to construct a distribution profile of the total turbulent kinematic viscosity and the average flow velocity in the collector pipe. It becomes possible to evaluate the efficiency of the flow movement both in the constituent elements (collector pipes) and in the closed collector-drainage network as a whole. And it also becomes possible to improve the methods of designing and calculating their technological and design parameters.
TopBackground
Climatic conditions are changing in the world, including changes in the amount and intensity of precipitation, soil moisture and rising air temperatures, total evaporation, and water demand of crops. They determine the need to ensure the productivity of drained lands through the application of adaptive measures for the regulation and accumulation of moisture in the soil and within the reclamation system, as well as the transition from periodic to regular soil moisture (Watkiss 2015, Labędzki et al. 2021).
At the same time, the technical condition of drainage systems built 40-50 years ago has deteriorated due to wear and tear and failure to perform the necessary set of operational measures. This has led to the deformation and siltation of the closed collector-drainage network, as the main regulating element of such systems that operate in the regime of drainage and soil moisture. As a result, their parameters deviated from the design. The regime of operation of the closed collector-drainage network was also disrupted and its capacity was reduced. Therefore, the overall efficiency of such systems and the productivity of drained lands have decreased by 25… 50% of the design system (Rokochinskiy et al. 2019a, Kovalenko et al. 2020).
Therefore, the issue of changing approaches to the creation and operation of water reclamation facilities on drained lands is extremely important. The methodologies for substantiation in projects of construction and reconstruction of drained systems, their optimal constructive decisions (type, design, parameters of systems, and components of their technical elements) should change. First of all, this is relevant for a closed collector-drainage network. It is a regulating element of the drainage system and can work in the regime of drainage and in the regime of moisture.
At the same time, when designing and operating drainage systems at all stages of time management decisions (1-project, 2-planned operation, 3-operational facility management) (Hebbink et al. 1999, Rokochinskiy et al. 2020), it is extremely important to correctly (objectively) determine the parameters system and its components technical elements. These issues concern first of all the regulating closed collector-drainage network, as well as the leading network of canals, regulating and supporting hydraulic structures, pumping stations, etc. They determine the cost of the system, its overall technological, economic, and environmental efficiency.
In the 70-80s of the last century, the issues of automation of water regulation management and production processes of water distribution on drainage and humidification systems were solved by means of hydroautomatics to increase the efficiency of drainage systems with bilateral regulation of the water regime of lands (Kamra et al. 2019, Rokochinskiy et al. 2019b, Kovalenko et al. 2021).
These developments on the methodology of creation and operation of drainage systems were of a high scientific level. They were included in industry standards and applied in practice. But, as practice and experience have shown (Kamra et al. 2019, Kovalenko et al. 2021, Seyedmohammadi et al. 2016, Rokochinskiy et al. 2021), unfortunately, the required level of economic and environmental efficiency of land reclamation has not been achieved. Also, the reason for this was the lack of perfection of the methodology of design and calculation of such objects and its non-compliance with the requirements. This methodology did not take into account the relationship between the mode of operation of the closed collector-drainage network and the water regime of drained lands.