Effect of Soil Surface Slope on Water Distribution Uniformity for Stationary Sprinkler Systems

Abstract

The research included studying the effect of the slope of soil surface on water distribution uniformity of stationary sprinkler systems. 30 tests were conducted to obtain the pattern of water distribution along the radius of the wetting circle, where the sprinkler at the center, using 6 different sprinklers heads. In addition, different slopes of the surface were considered to study the wetting pattern, obtained by calculating the vertical deflection from the sprinkler head riser. 420 patterns of field water distribution were found for five slopes of the ground surface at seven different spacing, using rectangular and triangular arrangement of six sprinkler heads. It has been concluded that both of the uniformity coefficient CU and the distribution coefficient DU decrease with the increase of the soil surface slope, (87.5% and 89% of the cases respectively). In addition, The mean percentages of maximum decrease in UC and DU due to the gradient increase from 0% to 20% for all sprinkler heads was 3.17% and 6%, respectively.and the pattern of the water distribution does not change with the change of the soil surface slope, but rather the depth of water decreases and the range of the spraying increases as the negative slope decreases, and vice versa, the rate of water depth increases and the range of spraying decreases as the positive slope increases. Two equations were concluded to calculate the uniformity coefficient CU (or the distribution coefficient DU) for the distribution of water spray over lands with different slopes as a function of the slope and the uniformity coefficient CU (or the distribution coefficient DU) for the distribution of the water spray on flat surfaces with coefficients of determination of 0.98 and 0.977, respectively.