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Wind‐erosion Direction Factors as Influenced by Field Shape and Wind Preponderance
Author(s) -
Skidmore E. L.
Publication year - 1987
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1987.03615995005100010041x
Subject(s) - ellipse , shape factor , orientation (vector space) , geometry , wind direction , wind speed , field (mathematics) , erosion , traverse , aeolian processes , geodesy , physics , geology , mathematics , meteorology , geomorphology , pure mathematics
This investigation expands and improves the procedure for determining median travel distance of wind in traversing a field, information used in solving the wind‐erosion equation. Wind‐erosion roses were simulated by the equation of an ellipse in polar coordinates. The ratio of semimajor axis to semiminor axis was varied to give preponderance values from 1.0 to 4.0. The axis was rotated to simulate field orientation from 0 to 90° relative to prevailing winderosion direction. Length/width ratio for rectangular fields was varied from 1 to 10. The wind‐erosion direction factor, a number that when multiplied by field width gives median travel distance, was calculated for many combinations of variables. When preponderance was 1.0, the wind‐erosion direction factor was 1.03, 1.42, 1.48, and 1.48 for rectangular fields with length/width ratios of 1, 2, 4, and 10, respectively; the factor was not influenced by field orientation. As preponderance increased, the wind‐erosion direction factor approached unity for small angles of deviation and approached the length/width ratio for large angles of deviation. For circular fields surrounded by a nonerodible surface, the wind‐erosion direction factor was 0.91, regardless of wind direction and preponderance.