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As mountain tourism rapidly expands in remote landscapes, there is a critical need for improved disaster risk management to ensure the safety of tourists and industry workers, safeguard infrastruct...

We here investigate the geometry, age, and history of several enigmatic northern Thailand earthwork entrenchments that are mostly located on hills and could not have held water to form moats. The earthworks are either oval or rectangular in plan view and typically encircle 0.3 to 1 sq km areas with no potsherd debris that would indicate former towns. Most trenches are 3–5 m deep with inner walls 4.5–8 m high. Some encircling earthworks are concentric double trenches spaced approximately 10 m apart. Historians have suggested these earthworks enclosed defensible areas where people in outlying villages sought refuge when under attack by neighboring rulers, the Chinese Ho, or the Burmese. We argue that some encircling entrenchments may have been for the capture or containment of elephants. Nearly all of the once near-vertical original walls have degraded to slopes of 32–47°. Fitting calculated curves of the diffusion-based scarp-degradation model to our height-slope data, and assuming most scarps have degrade...

The primary purpose of soil conditioner application is to enhance a soil's resistance to erosion processes by increasing the water stability of aggregates. In this study, a wrist‐action shaker was used to assess the aggregate stability of three Hawaiian soils treated with an anionic surfactant soil conditioner (AGRI‐SC). Aggregates of 2.00 to 4.00 mm in size were treated with Agri‐SC at rates of 1 to 100,000 times the manufacturer‐recommended rate of 0.30 L ha‐1. The manufacturer‐recommended application rate of Agri‐SC was effective for only the most stable soil tested (Kaneloa Oxisol), ineffective for the Lualualei Vertisol, and adversely effective for the Molokai Oxisol. For higher application rates ranging from 10 to 10,000 times recommended, stability of large aggregate fractions increased for the Kaneloa Oxisol. In sharp contrast, the same application rates decreased aggregate stability of the Molokai Oxisol. For the third, least stable soil (Lualualei Vertisol), Agri‐SC was relatively ineff...

A new method is introduced to measure water stability of soil aggregates. The wrist‐action shaker is a simple, inexpensive tool that provides highly accurate data for the assessment of soil erodibility. Three soils from Hawaii (two Oxisols and one Vertisol) with different mineralogies, management histories, and potassium (K)‐factors were examined in this study. Six indices of water stable aggregation were determined after rapid immersion of air‐dry aggregates, followed by gentle wet‐sieving. Single‐sieve indices of percent water stable aggregates (WSA) 0.25 mm, and > 1.00 mm, were highly correlated. Additionally, these indices were highly correlated with three multiple sieve indices, namely geometric mean aggregate diameter (GMAD), arithmetic mean aggregate mass diameter (MAMD), and the coarse‐to‐fine index (CFI = % WSA > 1.00 mm / % WSA Molokai Ox...