Wednesday, November 15, 2006

Correlating Soil-Texture, -Moisture and –Infiltration Capacity to Bulk Electrical Conductivity Measurements using Electromagnetic Induction Mapping in Small Watersheds.

David A. Robinson1, Mark Seyfried2, Hiruy Abdu3, and Scott Jones3. (1) Stanford Univ, Dept of Geophysics, 397 Panama Mall, Stanford, CA 94305-2215, (2) USDA-ARS, 800 Park Blvd, Plaza IV, Boise, ID 83712-7716, (3) Utah State Univ, 4820 Old Main Hill Ags 160, Logan, UT 84322-4820

The development of an integrated approach to characterizing small watersheds is crucial to understanding the complex links and feedback mechanisms within them. We present preliminary work from a small watershed study at the USDA’s research watershed at Reynolds Mountain, ID. This work combines the use of GIS and digital elevation models with soil mapping using electromagnetic induction sensors. Our long term aim is to provide quantitative soils information, including soil-hydraulic conductivity, -moisture, -depth and -texture that can be incorporated into physically based models for prediction of hydrological responses. As a first approximation soil moisture storage is linked to soil depth, and infiltration capacity to texture via hydraulic conductivity. We have used the Dualem EM sensor to generate an apparent electrical conductivity (ECa) survey map of a small catchment at Reynolds Mountain. Current work is looking at methods of developing the best calibration methodology to interpret the ECa response. This approach provides higher resolution and more accurate hydrological model soil characteristics compared to conventional approaches using estimates taken from soil surveys within a watershed.