Field evaluation of water flow performance and application efficiency for border irrigation

Field experiments were conducted in a sandy soil in the arid region to investigate the influences of border dimensions and irrigation variables on the performance of water advance and recession, application efficiency and distribution uniformity (DU). In the experiments, all the borders studied had an approximately equal slope and constant length of 60 m, while the width of the border strips was varied from 1 to 4 m and the inflow rate was varied from 3.8 to 15.2 L/(s·m). Results showed that the relationship between advance distance and time could be represented by a power function. Of the borders studied, 1 m-wide borders gave the lowest application efficiency, whiley borders with 2 and 3 m in width gave an approximate similar efficiency. Application efficiency showed a decreasing tendency as the border width increased from 3 m to 4 m. All the borders produced relatively low application efficiency, with an average value of about 0.5 for the whole irrigation season. Infiltration parameters (K and α) for Kostiakov's equation were estimated by a volume balance approach and distribution uniformity (DU) for infiltrated depth was calculated. It was found that DU varied with border width in a similar pattern to application efficiency. A high DU of greater than 0.75 was observed for most of the borders. The results suggest that a high DU value does not necessarily mean a high application efficiency for surface irrigation.