A case study for irrigation modernisation: I. Characterisation of the district and analysis of water delivery records

The analysis of water management in irrigated districts is highly relevant. The present work highlights the principal irrigation management problems of the irrigation district of Almudévar, a representative surface irrigation district located in the northeast of Spain. The predominant irrigation system is blocked-end borders. The study included three phases: (1) assessment of crop water requirements of the main crops of the study area; (2) characterisation of soil depth and soil water retention; and (3) analysis of the current irrigation practices based on the study of the 1994 water records of the district. The following irrigation management problems were identified: (1) the mean volume of water billed to the farmers was 43% higher than the net irrigation requirements; (2) the volume of water billed to the farmers were inversely related to the farm size; (3) few, widely spaced, large irrigation events; (4) large delay time in water delivery; and (5) in selected crops and/or areas, water billing was lower than the net irrigation requirements, indicating the presence of marginal areas or heavily subsidised crops. This research could be applied in other areas of traditional surface irrigation systems. The goal of this methodology is to diagnose the actual level of water management and to provide data for the modernisation of the irrigation district. In a companion paper, a decision support system for the modernisation of the district is presented.