TITLE:
Spatial Distribution of Surface Soil Moisture in a Small Forested Catchment
AUTHORS:
Shoji Noguchi, Yoshio Tsuboyama, Roy C. Sidle, Tayoko Kubota
KEYWORDS:
ADR Sensor, Soil Water Content, Spatial Heterogeneity, Temperate Forest, Topographic Index
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.13,
September
29,
2014
ABSTRACT: Predicting
the spatial distribution of soil moisture is an important hydrological
question. We measured the spatial distribution of surface soil moisture (upper
6 cm) using an Amplitude Domain Reflectometry sensor at the plot scale (2 × 2
m) and small catchment scale (0.84 ha) in a temperate forest. The spatial
variation of soil water content was higher during dry conditions than that
during wet conditions. Results indicated 3.1 samples at the plot scale were
sufficient to estimate mean soil water content when the precision was 0.1. Soil
water content increased with increasing topographic index (TI) and soil-topographic index (STI)
at the small catchment scale. The correlation between soil water content and TI was higher than that between soil
water content and STI. This suggests
that topography is more important for estimating surface soil moisture than
soil depth as formation of surface soil moisture occurs at ≤6 cm.