Snowmelt Infiltration Determination using Heat Pulse Probe and Snow Lysimeter Techniques compared with an Energy Balance Model.

Snowmelt Infiltration Determination using Heat Pulse Probe and Snow Lysimeter Techniques compared with an Energy Balance Model

Changbing Yang - Dept. Plants, Soils and Climate, Utah State University, Logan, UT

Scott B. Jones - Dept. Plants, Soils and Climate, Utah State University, Logan, UT

The fate of precipitation and snowmelt are important inputs to hydrological modeling. Higher soil moisture content in springtime often results in increased runoff due to limited storage capacity and reduced infiltration rate (i.e., near long term rates) of the soil. Accurate measurements of subsurface water flux are difficult to make and in fact are virtually non-existent compared to water content measurements. The major difficulty stems from the impact a measurement apparatus has on both the gradient and flow path, which are dynamic both temporally and spatially. The objective of this study was to evaluate the heat-pulse probe as a snowmelt infiltration measurement tool. A forest test site was instrumented with sensors under 4 native vegetation regimes. A snow lysimeter was also installed for comparison and snow depth sensors recorded snowpack ablation rates. The heat pulse probes with one heater needle surrounding four thermistor needles were installed at 5 cm depths in soil under snow pack. Air temperature, relative humidity, snow depth, albedo, and snow water equivalent were measured at each vegetation site and used as input for an energy balance model, UEB to simulate snowmelt outflow from snow pack. The heat pulse probe may prove valuable for recording the timing and rate of snow pack melt water in the near surface and deeper subsurface where interflow occurs.