Drainage outflow in different pipe-drainage variants on gleyic podzoluvisol in the Sava River valley

摘要

Five-year investigations (1995-99) were carried out on the experimental drainage field "Jelenscak", Kutina, in Croatia. The field is situated in the Sava River valley, on gleyic podzoluvisol. The trial involved eight pipe-drainage variants, differing in drainpipe spacing and backfilling. Drainpipe spacings of 15, 20, 25 and 30 m with gravel backfill and spacings of 10, 15, 20 and 25 m without gravel backfill were tested. The shortest duration of drainage outflow was recorded in the variant with a drainpipe spacing of 15 m with gravel backfill and in the variant with a drainpipe spacing of 10 m without gravel backfill. These values are significantly different (P<0.01) compared to the values obtained in other variants. Average monthly drainage outflows in the said two drainage variants are also significantly higher compared to the other test variants (P<0.01). The outflow peak in the studied variants ranged from 12.3 mm d(-1) up to 64.9 mm d(-1). Drainage outflows during the four-year period (1996-99), calculated using the numerical model SWAP-93, were confirmed by direct measurements on the trial field with 95.8% precision.