Subsurface Water Distribution in Surface Irrigation

Experimental data on subsurface water distribution from both level and graded irrigation furrows are presented. The data are reduced to dimensionless form for analysis and empirical equations are presented describing the subsurface wetting patterns. Finally, the uniformity of application along an irrigation run is shown to be dependent on both the infiltration equation of the soil and the speed at which the wetting front traverses the irrigation run. A chart is included relating the uniformity of water application to the infiltration characteristics and the ratio of the time needed for the water to traverse the run to the time needed for the average water application to infiltrate.