Mapping Spatial Patterns of Soil Moisture Along a Non-Perennial Headwater Stream

Many headwater streams shift between surface and subsurface flow over the course of a year or season. The purposes of this study were to analyze soil moisture patterns to determine, first, when and where a non-perennial stream dries during a severe drought, and second, if characteristics such as vegetation greenness derived from a normalized difference vegetation index (NDVI) and topography of the surrounding landscape predict hydrologic connectivity to a stream. Within two weeks in June 2021, 424 volumetric water content (VWC) measurements were taken at 3-meter grids along a 150 m by 21 m area surrounding the North Fork of Gibson Jack Creek in Pocatello, ID, which included alternating wet and dry portions of the creek. VWC was high not only surrounding flowing reaches, but also in topography-predicted channels that had no visible depressions. Local NDVI was compared to relative soil moisture content, but there was no significant difference in NDVI between wetter and drier areas. Future work will include comparing soil moisture to NDVI from previous summers to determine the effects of the seasonal timing of stream drying and patterns that may have only emerged in the 2021 drought