WRRCTR No.148 Soil and Sampling Scheme for Characterizing Soil Hydraulic Properties of a Watershed

dc.contributor.author Bresler, Eshel
dc.contributor.author Green, Richard E.
dc.date.accessioned 2008-07-17T22:36:55Z
dc.date.available 2008-07-17T22:36:55Z
dc.date.issued 1982-12
dc.description.abstract Watershed modeling, which incorporates the stochastic nature of the hydraulic properties of the land surface and rainfall, requires a mathematical description of watershed variability, including the frequency distribution of key hydrologic parameters and the spatial structure of variances. Heterogenous watersheds require extensive sampling to characterize the spatial distribution of a property, such as hydraulic conductivity, which is frequently required as input to model calculations of infiltration and runoff. Since hydraulic conductivity, K, varies with water content, Ө, and soil water pressure, h, the K(Ө) and X(h) relationships can be conveniently represented by parameters in mathematical expressions relating these variables. The parameters of three different equations are examined as indices of the hydraulic properties of Oxisol soils in Hawaii's Pearl Harbor watershed. When what to measure and how to mathematically express the results is decided, the number and location of field measurement sites in a particular watershed are determined. Geostatistical concepts are applied to design a sampling scheme for a specific watershed in which the measured value of a hydrologic property or index at a given point is correlated with other measured values of the property that is dependent on the distance between sampling points. Required statistical parameters for the geostatistical approach are the mean, variance, and autocorrelation function or variogram. Criteria are specified for selecting the location and smallest possible number of observation points to best estimate the statistical parameters. The results suggest that 30 measurement sites are the minimum sample size for estimating the parameters required for stochastic modeling. The proposed sampling procedure is illustrated with a sampling strategy for a portion of the Pearl Harbor watershed.
dc.description.sponsorship U.S. Department of the Interior Office of Water Policy Grant/Contract No. 14-34-0001-2113 (A-094-HI)
dc.format.extent vii + 42 pages
dc.identifier.citation Bresler E, Green RE. 1982. Soil parameters and sampling scheme for characterizing soil hydraulic properties of a watershed. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC technical report, 148.
dc.identifier.uri http://hdl.handle.net/10125/1983
dc.language.iso en-US
dc.publisher Water Resources Research Center, University of Hawaii at Manoa
dc.relation.ispartofseries WRRC Technical Report
dc.relation.ispartofseries 148
dc.subject hydraulic conductivity
dc.subject hydrologic models
dc.subject sampling statistics
dc.subject surface-groundwater relationships
dc.subject soil water
dc.subject watershed (basins)
dc.subject Monte Carlo method
dc.subject Hawaii
dc.subject soil hydraulic indices
dc.subject geostatistics
dc.subject saturated conductivity
dc.subject drainage-flux method
dc.subject kriging
dc.subject autocorrelation
dc.subject variogram
dc.subject spatial variability
dc.subject oxisols
dc.subject Pearl Harbor
dc.subject Oahu
dc.subject.lcsh Hydrologic cycle -- Mathematical models.
dc.subject.lcsh Hydrologic models -- Hawaii -- Oahu.
dc.subject.lcsh Oxisols -- Hawaii -- Oahu.
dc.subject.lcsh Pearl Harbor (Hawaii)
dc.subject.lcsh Watersheds -- Hawaii -- Oahu -- Mathematical models.
dc.title WRRCTR No.148 Soil and Sampling Scheme for Characterizing Soil Hydraulic Properties of a Watershed
dc.type Report
dc.type.dcmi Text
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