EVALUATION OF THE EFFICIENCY OF DRAINAGE SYSTEMS AS A FUNCTION OF RANDOM VARIABLES

Abstract

Supplementing well-established deterministic dependencies with probabilistic ones allows for the determination of probabilistic limits of the corresponding system parameters, including drain spacing, drain intake capacity, and the change in groundwater level decline time. This makes it possible to justify changes in the size of system elements as needed, without compromising the quality indicators of the functioning of the hydromelioration system and ensuring its effective operation.The article analyzes the impact of groundwater levels on the yield of crops grown in a drainage system, as well as the impact of drain spacing on the average groundwater level during the growing season and on the change in groundwater decline time.An increase in the average groundwater level during the growing season by 10–15% compared to the calculated drainage standard with a probability of no more than 0,025–0,05 can lead to a decrease in yield of only 1–2%.Since crop formation in a drainage system is the result of the influence of many factors, it can be considered that the calculateddecrease in yield by 3–6% due only to a 10–15% increase in drain spacing is insignificant. If all other positive factors are preserved, this decrease in yield can occur with a probability of 0,025–0,05.Increasing drain spacings calculated using formula (3) [5] for drainage systems by 1,15–1,20 times can raise the calculatedgroundwater level by 10–15% compared to the calculated drainage standard, which does not lead to a decrease in yield.Increasing drain spacings calculated using formula (3) [5] by 1,15–1,20 times can increase the time it takes for groundwater levels to decline by 20–30%. However, this increase in time does not exceed the limits proposed by the standards [5] for the respective crops. In this case, a saving of drainage pipes of 10–13% can be obtained per 1 ha of drained area. Designing drainage with rational spacing between drains ensures an acceptable variation in groundwater levels across thesystem area, which creates the conditions for achieving the design yield.