Influence of wind and bed slope on water and soil moisture distribution in solid-set sprinkler systems

摘要

The present study was carried out to investigate the effects of wind and bed slope on uniformity of water and soil moisture distribution in solid-set sprinkler systems. For that, six plots of 25 x 30 m with bed slopes varying from 1.3 to 13.4% were selected in the Bileh-Savar Sprinkler Irrigation Network in Iran. For each plot, uniformity of water distribution and soil moisture monitoring tests were performed with three replications under different climates and operating pressures. In each of the tests, water application depth and soil moisture were measured at 164 and 143 spots in each plot, respectively. Based on computations and with regard to the ranges of environmental and systemic variations, uniformity coefficients of water application varied from 45 to 84%. In order to investigate the variations among different parameters, a number of relations were obtained to hold among different assessment indices. The results showed that proper management of the operating pressure during irrigation could largely cancel out the negative effects of high wind speed and also its variations on water application uniformity. The sensitivity analysis of the relations obtained also revealed that the uniformity coefficient of soil moisture is more sensitive to the uniformity coefficient of water application than to plot bed slope. Also, the fields with milder bed slopes are more suitable for improving uniformity of soil moisture distribution. The findings indicate a more uniform distribution of soil moisture compared to that of water depth across the plots. Hence, it seems that in arid and semi-arid areas where water resources are scarce, there will be no need for higher water consumption to increase uniformity of water application beyond 75%. Copyright pb 2008 John Wiley & Sons, Ltd.