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An Approach Toward a Physical Interpretation of Infiltration‐Capacity
Author(s) -
Horton Robert E.
Publication year - 1941
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/sssaj1941.036159950005000c0075x
Subject(s) - citation , interpretation (philosophy) , infiltration (hvac) , library science , computer science , sociology , geography , meteorology , programming language
INFILTRATION-CAPACITY was first defined 1 by the author as the maximum rate at which a given soil when in a given condition can absorb rain as it falls (6, 7). Infiltration-capacity is usually designated by f, and since f varies with time, especially during the early part of rain, it is to be understood that the condition of the soil and hence the infiltration-capacity, vary with time, until a certain minimum infiltration-capacity fc is reached. It would be better to use the term "terrain" rather than the term "soil" in discussing infiltration-capacity, for the reason that infiltration-capacity is governed not only by soil in the ordinary sense— comminuted mineral matter, with more or less organic matter—but in the broader sense of the soil as involving not only its mineral composition, texture and micro-structure or ordinary crumb-structure but also its macro-structures, including root systems, root perforations, sun-checks, earthworm perforations and other biologic structures, and its vegetal cover. Certain other factors, such as temperature of the air, and of rain and soil surface, rain intensity, initial soil-moisture, initial and residual rain occurring at intensities less than the infiltration-capacity, also require consideration. In a previous paper the author showed that f has an initial value fo at the beginning of rain and that if rain is continued at an intensity i> f, the infiltrationcapacity will decrease with rain duration in accordance with the equation (8) -K£t f = f.+ (fo-f c )e . i This was originally given as an empirical equation. It can, however, be derived from the simple assumption that the processes involved in the reduction of f as rain continues are of the nature of exhaustion processes. These processes include rain-packing, inwashing, breaking down of the crumb-structure of the soil, the swelling of colloids and, in cases where they occur, the closing of sun-checks. The graph of an inverse exponential equation can be represented over a considerable range by a hyper-