Seepage loss from a canal in Sri Lanka measured using tritium tracer

Abstract

Using single borehole dilution technique, and tritiated water as tracer, lateral flow rate of water near the phreatic line has been measured at 24 points along the banks of an unlined canal. Permeability values range from 0.5×10^-6 m sec^-1 to 34×10-⁶ m sec^-1; the median value being 5×10^-6m sec^-1. The seepage loss is estimated to be 5×10^-5 m³ sec^-1 m^-1. For the entire canal the value is 0.74 m³ sec^-1 which is 12% of the total flow. Limitations and merits of the technique are discussed.