Irrigation properties of Kuchurgan and Baraboi Water Reservoirs

Abstract

The problem of irrigation of agricultural lands in the southern part of Ukraine, including Odesa Region, has been and still remains extremely important. The limited amount of water resources of irrigation quality forces the nation to create artificial reservoirs for water accumulation with the purpose of their further use for irrigation. Sources of reservoirs recharge in the southern part of Odesa Region usually include the Danube and the Dniester whose waters meet irrigation conditions. However, mixing the Danube or Dniester water with the water from natural reservoirs, together with the influence of local factors of water quality formation, lead to changes in water masses properties. Sasyk Reservoir is one of the examples: the water from the reservoir, when mixed with the Danube water, may be used for irrigating only light, well-permeable and drained soil, whilst the Danube water is suitable for irrigating all types of soils throughout the warm period of the year. The article presents an overview of different methods of irrigation water assessment. It offers detailed typification of irrigation waters based on natural waters typification offered by Aliokin O.A., and includes a table for calculating the concentration of toxic hypothetical salt in water samples of different subtypes. The water quality assessment of Kuchurgan and Baraboi Reservoirs was performed according to the studied methods. It is found that the irrigation properties of their water masses significantly differ. Kuchurgan Reservoir: mineralization of water during 90% of the warm period (WP) is in the range of 1-3 g/dm3; according to the classification of Kostiakov A.M. such water faces "increased danger" of salinization (category 3); the amount of toxic salts does not exceed 2.4 g/dm3; water of subtype IIb (84% of the WP); composition of toxic salts is represented by NaCl (max 0.92 g/dm3), Na2SO4 (max 0.79 g/dm3) and MgSO4 (max 1.5 g/dm3); the total content of chloride and sodium sulfate in the water does not exceed the standard value for watering light, well-permeable and drained soils; the magnesium content promotes salinization during 70-75% of the WP. Baraboi Reservoir: water salinity does not exceed 1 g/dm3; according to Kostiakov A.M. watering requires a "careful approach" (category 2) during 71% of the WP, and 29% of water falls into "good" category (category 1); the ratio of major ions refers to subtypes IIa (53%) and IIb (41%); according to Bezdnina S.Ya. water belongs to category I (suitable for irrigation of all types of soils) with a probability of 65% during the WP and to category II (suitable for irrigation of most types of soils) – with 35% probability; the amount of magnesium adversely affects the soil during 53% of the WP. The water masses of Kuchurgan and Baraboi Reservoirs are suitable for irrigation, but require a careful approach due to the possibility of magnesium salinization. The water of Baraboi Reservoir has the best irrigation properties and is suitable for watering most types of soils. The water of Kuchurgan Reservoir may be used only for watering light, well-permeable and drained soils.

Keywords

• irrigative assessment
• water quality
• kuchurgan reservoir
• baraboi reservoir
• detailed typification of irrigation waters
• salinization