EVALUATING WATER DELIVERY IN TERTIARY UNITS .1. METHOD

In most irrigated areas, the present desire for rehabilitation raises the need for an accurate analysis of the actual situation. We present a new method to evaluate the quality of water delivery and the origin of water deficits (and irrigation water losses) in an irrigated area, based on the simultaneous analysis of distribution rules and actual ir rigation events. First, a daily water balance simulation allows us to quantify water deficits and losses at plot level. Then, our calculatio n method allows us to identify their various origins within the framew ork of water-delivery rules and actual practices within the hydraulic block. The basic principle is the comparison between real and fictitio us events. Although the operational cost of the presented method is lo w, the collected data produces a considerable amount of information. I t enables one to analyse both the overall results, and the variability of farmers' behaviours. Results obtained by this method, in the case of a 170ha farmer-managed irrigation system in Ecuador, are presented in the companion paper. (C) 1997 Elsevier Science B.V.