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The effect of rainfall intensity on storm flow and peak discharge from forest land
Author(s) -
Hewlett J. D.,
Fortson J. C.,
Cunningham G. B.
Publication year - 1977
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr013i002p00259
Subject(s) - storm , intensity (physics) , environmental science , hydrology (agriculture) , watershed , flow (mathematics) , atmospheric sciences , climatology , meteorology , geology , geography , mathematics , physics , geotechnical engineering , quantum mechanics , geometry , machine learning , computer science
Analysis of an excellent 30‐year record of rainfall and storm flow (545 events) from a 3‐mi 2 forested watershed in the southern Appalachians was made to determine whether rainfall intensity influences storm flow volume or peak discharge per unit area. For all practical purposes, hourly and minutely rainfall intensities during storms had no effect on storm flow volumes delivered by the basin. Storm rainfall P , antecedent flow I , season (winter or summer), and duration of the rainstorm D accounted for 86.4% of the total variation in the log of storm flow. Addition of maximum 60‐, 30‐, 15‐, and 5‐min intensities raised this to 86.7% (the increase was not significant at the 0.05 level) but reduced the standard error (0.354 in logs) by less than ½%. The same four variables ( P , I , S , and D ) accounted for 72% of the variation in the log of peak flow. Addition of the intensity variables raised this to 76.7% (increase significant at the 0.01 level). Thus only 4.7% of the total variation in the log of peak flow was attributable to intensity. Analysis by eight storm rainfall classes reinforced the conclusion that intensity added nothing to storm rainfall as a predictor of storm flow regardless of storm magnitude. P , I , S , and D accounted for 25–65% of the total variation in the log peak flows within storm classes; addition of all intensity variables raised this to 36–85%, but the increases were nonsignificant at the 0.05 level in four of the eight classes. A strong inference is made that neither estimates nor measurements of hourly and minutely rainfall intensity are of practical value in predicting storm flow volume from this forested basin. Furthermore, intensity played a much smaller role in peak discharge generation on this basin than was expected. The hypothesis is offered that rainfall intensity variation is not a dominant variable controlling flood generation in humid region, wild land watersheds.