The Effect of surface head on infiltration rates based on the performance of ring infiltrometers and ponds

Abstract

Studies with infiltrometers and small ponds indicate that the normal relatively low infiltration rates of certain soils may be increased by providing sufficient depth of water or surface head on the soil surface. Infiltration rates increased directly proportional to head motivating flow in infiltrometers and ponds on untreated soil under water‐spreading conditions. Hydraulic head loss and length of saturated soil column explain why greater increases in infiltration rates occurred with increases in surface head on untreated soil than on a soil rendered more permeable by treatment. Hydraulic head losses were obtained with infiltrometers equipped with manometers located 1 ½ 4 ½, and 7 ½ inches below the soil surface. The resistance of untreated soil to flow reduced the total head motivating flow to a negligible amount at a depth of 7 ½ inches below the soil surface. Where hydraulic head exists at the bottom end of an infiltrometer extending into the soil, the need for a “balanced buffer” rather than a “partial buffer” or an “excessive buffer” to prevent lateral flow is discussed. Piezometric heads in relatively pervious soil horizons below the soil surface within and outside of a pond are reported.