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Runoff responses to soil heterogeneity: Experimental and simulation comparisons for two contrasting watersheds
Author(s) -
Luxmoore R. J.,
Sharma M. L.
Publication year - 1980
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/wr016i004p00675
Subject(s) - surface runoff , evapotranspiration , environmental science , hydrology (agriculture) , soil water , hydraulic conductivity , watershed , drainage , runoff curve number , soil science , geology , ecology , biology , geotechnical engineering , machine learning , computer science
Simulated annual water budgets and daily streamflows for a well‐managed (R5) and an overgrazed grassland (R7) watershed at Chickasha, Oklahoma, were computed with the one‐dimensional terrestrial ecosystem hydrology model (TEHM, Huff et al. (1977 a )) in which the soil hydraulic properties were scaled according to similar media criteria. The scaling factors and the area contributions for seven scaled soils were represented by a log normal frequency distribution based on measurements from an earlier study. Drainage and runoff were greatly influenced by change in scaled soil properties, and there were increases in evapotranspiration at smaller scaling values (finer soils). More runoff was generated from the overgrazed watershed which had lower evapotranspiration and lower hydraulic conductivity. Despite consideration of spatial variability in soil hydraulic properties, surface runoff generated from the scaled soil frequency distributions proportionally accounted for only 29 and 55% of simulated streamflows from the R5 and R7 watersheds, respectively. An algorithm that represented lateral subsurface flow to the streambed as a function of soil drainage rate was used in the one‐dimensional model to derive agreement between the observed and measured streamflows. For both watersheds the simulated runoff from the log normal distribution of soils was closer to the measured value than the runoff from the mode, median, or mean soils. The comparisons between measured and simulated soil water contents showed significant differences even though the streamflows showed agreement.