Features of inundation irrigation in Yakutia

Abstract

Inundation irrigation in Yakutia compared to other regions of the Russian Federation has its own features. The hydrological regime and hydrographic characteristics of small rivers allow irrigating once a year with flood waters on frozen or partially thawed soil. Water is diverted to irrigated areas without pumping by hydraulic structures built in river beds with subsequent return of irrigation water back to the river downstream. One of the features in the inundation irrigation is the peculiarity of the natural conditions associated with the presence of permafrost soils, geomorphological features of agricultural landscapes (drained lakes), and the effect of permafrost on the thermal regime of soils under the conditions of a short growing season. The experience of inundation irrigation shows that despite the zone of risk farming, the use of this irrigation method allows increasing crop yields 2-3 times. The conducted field studies and analysis of meteorological conditions show the impact of climate change on soil thermal regime in inundable meadows in Yakutia. The analysis of hydrometeorological data and moisture availability over the past 55 years shows the increase of atmospheric air temperature up to 4°C, increase of precipitation amount up to 15 mm and moisture deficit during the growing season up to 70 mm in the study area. The studies of soil temperature regime show the increase of the active soil layer. Alongside, relatively low rates of increase of thawing in irrigated soils compared to non-irrigated soils allow concluding that the impact of climate warming on soil thawing under inundation irrigation is reduced.