Effects of Deforestation on Water Flow in the Vadose Zone

The effects of land use change on the occurrence and frequency of preferential flow (fast water flow through a small fraction of the pore space) and piston flow (slower water flow through a large fraction of the pore space) are still not fully understood. In this study, we used a five year high resolution soil moisture monitoring dataset in combination with a response time analysis to identify factors that control preferential and piston flow before and after partial deforestation in a small headwater catchment. The sensor response times at 5, 20 and 50 cm depths were classified into one of four classes: (1) non-sequential preferential flow, (2) velocity based preferential flow, (3) sequential (piston) flow, and (4) no response. The results of this analysis showed that partial deforestation increased sequential flow occurrence and decreased the occurrence of no flow in the deforested area. Similar precipitation conditions (total precipitation) after deforestation caused more sequential flow in the deforested area, which was attributed to higher antecedent moisture conditions and the lack of interception. At the same time, an increase in preferential flow occurrence was also observed for events with identical total precipitation. However, as the events in the treatment period (after deforestation) generally had lower total, maximum, and mean precipitation, this effect was not observed in the overall occurrence of preferential flow. The results of this analysis demonstrate that the combination of a sensor response time analysis and a soil moisture dataset that includes pre- and post-deforestation conditions can offer new insights in preferential and sequential flow conditions after land use change.

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ARMA sensor response time analysis. Final report. [PWR; BWR]

10.2172/5446029 ◽

1980 ◽

Author(s):

R. L. Currie ◽

C. W. Mayo ◽

D. M. Stevens

Keyword(s):

Response Time ◽

Sensor Response ◽

Final Report ◽

Response Time Analysis ◽

Time Analysis

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Ponded infiltration into soil with biopores — field experiment and modeling

Biologia ◽

10.2478/s11756-009-0078-7 ◽

2009 ◽

Vol 64 (3) ◽

Cited By ~ 8

Author(s):

Michal Dohnal ◽

Jaromír Dušek ◽

Tomáš Vogel ◽

Milena Císlerová ◽

Ľubomír Lichner ◽

...

Keyword(s):

Water Flow ◽

Preferential Flow ◽

Water Pressure ◽

Three Dimensional ◽

Detailed Knowledge ◽

Dye Tracer ◽

Simulation Based ◽

Flow Through ◽

Flow Effects ◽

Infiltration Experiment

AbstractPreferential movement of water in macropores plays an important role when the process of ponded infiltration in natural porous systems is studied. For example, the detailed knowledge of water flow through macropores is of a major importance when predicting runoff responses to rainfall events. The main objectives of this study are to detect preferential movement of water in Chernozem soil and to employ numerical modeling to describe the variably saturated flow during a field ponded infiltration experiment. The infiltration experiment was performed at the Macov experimental station (Calcari-Haplic Chernozem in Danubian Lowland, Slovakia). The experiment involved single ring ponded infiltration. At the quasi steady state phase of the experiment dye tracer was added to the infiltrating water. Then the soil profile was excavated and the penetration pattern of the applied tracer was recorded. The abundance of biopores as a product of fauna and flora was found. To quantify the preferential flow effects during the infiltration experiment, three-dimensional axisymmetric simulations were carried out by a two-dimensional dual-continuum numerical model. The water flow simulations based on measured hydraulic characteristics without consideration of preferential flow effects failed to describe the infiltration experiment adequately. The 3D axisymmetric simulation based on dual-permeability approach provided relatively realistic space-time distribution of soil water pressure below the infiltration ring.

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