Subsurface drainage in a pilot area in Nagarjuna Sagar right canal command, India

Abstract

Subsurface pipe and open drainage systems were installed in 8 and 5 ha area, respectively in farmers’ fields at Konanki pilot area in Nagarjuna Sagar project right canal command in India in the year 1999 to combat the problems of waterlogging (depth to water table, 0–3.7 m), salinity and sodicity (ECe, 1.3–18.6 dS/m; pH, 7.2–10.0 and ESP, 14.1–54.6). Two types of envelope materials, nylon mesh and geo-textile were used and two spacings of 30 m (design spacing) and 60 m (double the design spacing) were adopted for the pipe drainage system. The analysis of discharge data from the individual pipe drains revealed that among both the spacings, the drains enveloped with geo-textile performed better (0.45–1.85 mm/day), when compared with those enveloped with nylon mesh (0.25–0.86 mm/day). The effectiveness of drainage systems in the control of waterlogging at the pilot area has been monitored through a network of 61 observation wells. The groundwater table, which used to be almost at the ground surface during the main crop season (October–February) before installation of drainage systems, could be lowered by 0.2–0.35 m due to the installation of drainage systems. A total of 50.4 (@ 6.3 tons/ha) and 115.6 tons (@ 23.1 tons/ha) of salts have been disposed through pipe and open drainage systems, respectively during the period of 3 years (1999–2002).