Verification of flow processes in soils with combined sprinkling and dye trace experiments

Washington D.C.

2001

11 S.

9 Abb., 1 Tab., 23 Lit. Ang.

Bandaufführung

153712

Water flow in soils is influenced by macropores, by the heterogeneity of the soil matrix, and by the exchange of water between macropores and the soil matrix (interaction). The degree of interaction influences the runoff generation process in soils with macropores during extreme rainfall events. Despite a well developed macropore network, rapid overland flow can be generated due to low interaction in combination with low permeability in the subsoil. Low interaction in combination with permeable lateral flow pathways in the subsoil, however, results in bypassing of the topsoil and the generation of rapid subsurface flow. The water movement during Infiltration and the resulting flow paths were studied with sprinkling experiments and dye tracing under different rainfall intensities and soil moisture conditions. The dye tracer was continuously applied with the sprinkling water on 1 m2 plots. After the sprinkling, cross-sections of the soil were prepared for surveying horizontal and vertical dye patterns, thus displaying the cumulated flow path in the soils. These experiments were carried out on sites, where different runoff generation processes were expected. The experimental results illustrate the influence of the water exchange between macropores and the soil matrix on runoff generation. The observed flow processes in macroporous soils depended on the water content of the soil matrix, the soil structure, the rainfall intensity and the water repellence near the soil surface. The verification of flow processes in the field was improved with combined sprinkling and dye tracer experiments.