STUDY OF INFILTRATION REGIME ON SOILS USING A PORTABLE RAINFALL SIMULATOR, A CASE STUDY IN COLOMBIA

A study of infiltration regime using simulated rainfall over in situ samples documents variations in infiltration pattern with time, slope gradient and intrinsic properties of the soil.  Previous soil erosion studies use laboratory rainfall simulator on disturbed samples removed from their natural conditions.  This study uses a portable rainfall simulator to make measurements of infiltration on in situ samples.  The investigation consisted of four stages: construction of rainfall simulator, development of method for measuring infiltration, field tests and analysis of results.  Tests were performed on soils at a constant slope angles (0^o and 15^o), at different slope angles and soils exposed to a simulated five day raining period.  Resistivity measurements taken in conjunction with the rainfall simulation enabled the detection of water movement throughout the soil and how it changes with time.  Data collected indicate that infiltration is reduced by water retained by the soil increasing runoff, soil is disaggregated and eroded by material drag, effective porosity decreases with increasing retention of infiltrated water, increased slope gradient causes less water to be retained by the soil and to penetrate to a shallower depth.