A New Perspective on Assessing the Real Water Savings Resulting from Irrigation Technology Interventions

Abstract

Poor water resource management is a major cause of water loss and exacerbates water shortages. In order to avoid some misconceptions and misunderstandings associated with irrigation efficiency, the term real water savings (RWS) has been introduced in contrast to apparent water savings (AWS). In this study, irrigation technology interventions were evaluated in terms of return flow and water saving in the Qazvin Plain irrigation network in Iran. This was accomplished using the REWAS tool developed by FAO to evaluate the effects of technological and management interventions on the RWS at the macro level (network, basin, etc.). According to the results, switching the irrigation system from furrow to center pivot with height-regulated sprinklers (Scenario A), center pivot with height-fixed sprinklers (Scenario B), linear-move irrigation system (Scenario C), and solid-set sprinkler irrigation (Scenario D), results in RWS of 390, 383, 326, and 331 mm, respectively. In turn, as a result of applying scenarios A, B, C, and D, the AWSs at the field scale were determined to be 90%, 88%, 75%, and 76%, respectively, while the RWS at the irrigation network scale was determined to be 19%, 19%, 17%, and 18%, respectively. Due to the influence of nonrecoverable return flows, the RWS is much lower than expected. In conclusion, the RWS can only be increased by preventing nonrecoverable return flows. The assessment of RWS can assist decision-makers in choosing sustainable interventions to improve agricultural water productivity by providing insight into field flows, irrigation networks, and basin scales.