Appraisal of canal hydraulics and field water balance components at distributary level in Hirakud canal command

Abstract

Seepage being the most governing process by which water is lost from the canal system and creates hindrance for efficient distribution in crop fields, the accurate estimation of conveyance loss is of paramount importance for proper management. A case study was carried out in Hirakud canal command area at distributary level to assess the prevalent canal hydraulics and its impact on overall distribution in irrigating the crop fields. While studying the conveyance loss in lined and unlined canal reaches in Bargarh distributary, total 84.8% less conveyance loss was obtained in lined canal sections with respect to unlined canal sections, when it was observed as 181.25 ls−1 in 100 m in unlined canal sections. Seepage losses computed by Davis-Wilson and Moritz equations for lined and unlined canal sections were found to be less than the measured values. Similarly, irrigation application efficiency was observed 28.75%, when ETcrop was 3.66 mm day−1. Thus there is priority requirement to augment canal infrastructure to increase the performance. Further, evaporation, transpiration and deep percolation rates are measured within 1.15–2.15, 3.0–4.55 and 1.0–2.35 mm day−1, respectively while studying through field scale water budget experiments in paddy fields during 2012 and 2013 rabi seasons, which are pre-requisite information for scheduling irrigation for crops in the command area.