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This 20-month study of a prairie hillslope seep system builds upon and extends the soil moisture record from a previous study conducted during the most extreme drought ever recorded in Texas. We seek to improve understanding of how prolonged drought impacts seep-headwater hydrology, and to determine how well dominant vegetation reflects changes in volumetric soil moisture (θv). Results show the entire hillslope saturates after storm events, but due to severe drought, no surface runoff or channel flow was recorded. We documented changes in soil moisture, with the highest θv occurring along the deeper footslope soils. We hypothesize hyperseasonal environments, or seasonal waterlogging/desiccation of upland vegetation in poorly drained soils, exist in the study area and are the first to quantify hyperseasonality, or % change in magnitude of θv throughout a hydrologic year. The seep and riparian plots aligned with lower hyperseasonality, indicating seasonal hypoxia, but not complete desiccation. High hyperseasonality occurred along the midslope barrens, indicative of a true hyperseasonal environment. We suggest a ≥ 90% threshold would likely indicate true hyperseasonal cyclicity of anaerobic and xeric regimes. Our results provide insight to how extreme drought impacts seep-headwater systems, and how predicted hotter, drier conditions may alter their hydrologic regime. [ABSTRACT FROM AUTHOR]

We consider finite groups with a given number of subgroups. With a carefully chosen definition of "similar," we find that for each positive integer k, the groups with exactly k subgroups fall into a finite list of similarity classes. [ABSTRACT FROM AUTHOR]

Presents the results of field measurements conducted in a small agricultural basin on the North Carolina coastal plain. Objective of the study; Role of storm runoff in sediment delivery; Results suggesting soil erosion in the region is more rapid and extensive than previously thought; Soil loss at the fields; Doubt expressed on assessments of the coastal plain as being a stable, non-eroding landscape; Discussion of the mobilized soil, which is redistributed and stored within the watershed with only a small portion of the soil eroded from slopes leaving the basin on an event time frame.