Effect of macropores on infiltration and percolation: An experimental investigation.

Abstract

The purpose of this laboratory investigation was to study the effect of soil macropores (large non-capillary pores) on infiltration and percolation. This was done by measuring runoff, infiltration and tile flow rates for different macropore populations. The increase in percolation occurring as a result of increased number of macropores is associated with an increased bypass of the soil matrix by percolating water. The basic infiltration capacity increased with increasing number of macropores. This observation was used to develop the concept of macropore index (M-index). In situations where soil M-index changes seasonally, it becomes difficult for appropriate equation parameters to be determined accurately. To enable Horton equation to calculate infiltration in macroporous conditions, an improved form has been suggested. The influence of increasing the population of macropores on surface runoff and tile flow has been investigated. Results indicate that hydrologic models should consider the influence of macropores where populations are likely to change significantly over time. (Abstract shortened by UMI.)