Usatyi S. Water quality control in drip irrigation systems

The dissertation presents the solutions to the scientific and practical issue of water quality control in drip irrigation systems based on improving technology, technological schemes of water treatment, technical means and designs of drip irrigation systems. The novelty of the obtained results is that for the first time it has been scientifically grounded the principles of irrigation water quality control in drip irrigation systems (DIS) based on improving the technology, technological schemes of water treatment, technical means and designs of drip irrigation systems. Water quality control takes into account the mechanism of hydrochemical and hydrobiological water composition formation on its way from the irrigation source to drip emitters, empirical dependences of the effect of irrigation water quality on the efficiency of water treatment technical means as well as flow-pressure characteristics of drip emitters of drip irrigation systems and pulsed water supply to improve the efficiency of drip emitters when using the irrigation water of poor quality. In the course of the research it was revealed the formation of stable complexes of organic suspended particles (aquatic organisms and detritus) directly in the irrigation network of DIS, high taxonomic and quantitative diversity of which is proposed to classify as a biological threat for drip irrigation systems, affecting the efficiency of drip emitters. The dependence of DIS efficiency on the content of suspended organic particles is proposed to be determined based on the deviations in flow rate characteristics of drip emitters. An improved method for predictive estimation of deviations in flow rate characteristics of drip emitters depending on the content of total iron and suspended organic particles is proposed. The method of predictive estimation of water flow rate deviations for drip emitters depending on the content of iron and suspended organic particles has been improved, which enables to predict the probability of reducing the operational reliability of SDI. It has been also established that the requirements for the quality of irrigation water directly depend on the size of the water canals of drip emitters. As a special criterion for the selection of the designs of drip emitters by the size of water canal, the content of suspended organic particles is proposed. To reduce the requirements for the quality of irrigation water, the possibility of using a pulsed water supply regime has been substantiated and a pulse drip emitter of a mortise and integrated type has been developed. An algorithm for selecting technological treatment schemes for water taken from both open and groundwater sources depending on the content of suspended organic particles in it is proposed. Based on the algorithm, nine technological schemes of water treatment and the design of drip irrigation systems have been substantiated, the application of which increases the operational reliability of DIS. The economic effect of applying the advanced technological schemes of water treatment and the designs of drip irrigation systems is achieved by reducing the operating costs for flushing, system operation and personnel, including the total cost for improving the design of existing drip irrigation systems.