ARS | Publication request: SPATIAL VARIABILITY CONSTRAINTS TO MODELING SOIL WATER AT DIFFERENT SCALES

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 1997
Publication Date: N/A

Technical Abstract: Physically-based soil water models are based largely on the results of point or small plot experimental work. Many applications are for much larger scales, however. Changing scale (or area of interest) may result in a change in the nature of spatial variability, from deterministic to stochastic, for example, which may simplify modeling by reducing the need for distributed data. We measured soil-water content at scales of 10 m2, 130,000 m2, 260,000 m2, and 240,000,000 m2 at different dates represent- ing different seasons. Depths of samples ranged from 10 to 30cm. Our results have three important implications to modeling over large scales. First, the amount of spatial variability changes considerably with sampling date, being lower when the soil was dry at all scales. This indicates that soil-water content may be accurately characterized over large areas under some conditions. Second, the amount of varia-bility e 130,000 m2 watershed was similar to that in the 10 m2 plot, indicating that it is reasonable to aggregate soil-water content within soil series. And third, introduction of additional soil series at the 260,000 m2 scale added significant variability of soil-water content. This further supports the soil series level of aggregation.