Drainage system construction influence on the groundwater level of reclaimed soils

Abstract

The influence of the drainage system construction on the formation of the regime of groundwater levels has been studied. The results of statistical processing of the data from parallel observations of meteorological parameters and groundwater levels over a 32-year period have demonstrated that groundwater levels are most closely correlated with the hydrothermic coefficient (HTC) of the previous period. With an increase in the degree of moisture, the groundwater level rises most rapidly in the first decade of May and is less subject to variations in the third decade of May. The highest groundwater level in the 1st decade of May with the long-time annual average HTC equal to 2 was observed in the shallow drainage option–35 cm, the lowest–in the two-tiered drainage option–70 cm. In an excessively humid year (HTC = 3.5), groundwater in the options of shallow drainage and collectors with filling the drainage trench with sand-gravel mixture (SGM) rise into the plough layer; and, when the HTC exceeds 4.5, in the options of shallow drainage and collectors with SGM, they reach the soil surface. In a wet year, the rate of groundwater decline is from 1.25 cm/day–in the option of two-tiered drainage to 2.00 cm/day–in the option of collectors with wood chip. In modern conditions of climate change, the most advanced drainage systems are the structures of two-tiered drainage and collectors with wood chip, which ensure timely drainage of groundwater. In a high-water year, the use of wood chip instead of a sand-gravel mixture in the collector structure will increase the rate of lowering of the groundwater level by 5%.