5 Comparison of Different Methods for Detecting Irrigation Canals Leakage Paolo Clemente, Manuela Lasagna, Giovanna Antonella Dino, and Domenico Antonio De Luca Abstract This research investigates some field methods to evaluate water leakage from irrigation canals, in order to find a reliable method of identifying and quantifying losses. This study was conducted in two canal lines in Piedmont, north-western Italy, which have different hydraulic, morphological, geological and hydrogeological contexts. A hydrogeological characterization of the study area was carried out for every investigated canal, in order to evaluate the relationships between groundwater and canal water. The water losses from irrigation canals were subsequently estimated using various methods. The methodologies are: empirical formulas, inflow-outflow test and two tracers method. Inflow-outflow test is easy to apply and ef ficient; however it sometimes is inadequate because of the high instrumental error, especially in canals with low velocity and discharge. The two tracers method is considered a more rigorous methodology, with a low error. This method is not reliable, however, in cases of low discharge and laminar flow, resulting in inadequate tracer diffusion. The comparison of the results shows that the empirical formulas heavily underestimated the real amount of the losses. The results of inflow-outflow method and two tracers method are similar, both in sandy- gravelly and impermeable bed canals. Keywords Irrigation canal  Water losses  Empirical formula  Inflow-outflow test  Two tracers method 5.1 Introduction On regional scale, the Piedmont irrigation network, located in northwestern Italy, consists of several tens of thousands km of canals. The loss of water due to seepage from these canals constitute a substantial part of the total conveyed water. Irrigation canals placed in natural soil are character- ized by water losses ranging from 20 % to more than 50 % (De Luca et al. 2012). Water losses cause economic, hydrogeological and environmental consequences; it is important to know the amount of such loss in order to cor- rectly set up the use and the management of water resources. P. Clemente  M. Lasagna (&)  G.A. Dino  D.A. De Luca Earth Science Department, University of Turin, via Valperga Caluso 35, Turin, Italy e-mail: manuela.lasagna@unito.it P. Clemente e-mail: paolo.clemente@unito.it G.A. Dino e-mail: giovanna.dino@unito.it D.A. De Luca e-mail: domenico.deluca@unito.it G. Lollino et al. (eds.), Engineering Geology for Society and Territory – Volume 3, DOI: 10.1007/978-3-319-09054-2_5, © Springer International Publishing Switzerland 2015 23