Estimation of soil loss at a regional scale based on plot measurements—some critical considerations

Roels, J. M.

doi:10.1002/esp.3290100606

Cited by 37 publications

(13 citation statements)

References 2 publications

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“…The most common sampling design used in reference areas is what Gilbert (1987) calls haphazard sampling, also known as convenience sampling. Roels (1985) noted similar problems when examining published erosion plot studies, Non-probability sampling was commonly used, and this invariably produced biased estimates, for bias is always present in human judgment. Non-probability sampling may suffice for a homogeneous population; however, this cannot be established a priori, and research has shown that many soil physical and chemical properties are highly variable in space (Dahiya et al.…”

Section: Introductionmentioning

confidence: 93%

Caesium-137 soil sampling and inventory variability in reference locations: A literature survey

Sutherland

1996

Hydrol. Process.

143

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Soil sampling design, the number of samples collected and the lateral variation of caesium-137 (I3'Cs) in uneroded reference locations were extracted from previously published work. The focus was on published work which used 137Cs reference inventory (Bq m-*) for qualitative or quantitative estimation of sediment redistribution SRD within the landscape. The objective of this study was to address one of the methodological concerns facing the Cs technique -that is. the lack of a rigorous statistical treatment of reference locations. The limited attention paid to the reference location is not justified as 'true' estimates of SRD are based on the assumption of an unbiased, independent, random probability sample estimate, commonly the arithmetic mean. Results from the literature survey indicated that only 1 1 % of the reference locations sampled for 137Cs expressly stated that a probability sampling design was used (transect or systematic-aligned grid). The remaining locations were generally sampled using a non-probability based design, more commonly known as haphazard sampling. Of the 75 reference study areas identified only 40 provided enough information to determine the dispersion around the mean, and from this the coefficient of variation (CV) was calculated for all available data. The median CV was 19.3%, with 95% confidence limits of 13.0-23.4%, indicating that a proximately 1 1 random, independent samples would generally be necessary to adequately quantify the reference ''Cs area activity with an allowable error of 10% at 90% confidence. Further analysis indicated that only one-third of the studies sampled a sufficient number of I3'Cs reference locations. This value would actually be lower as sampling frameworks were based on non-probability sampling procedures. For '37Cs reference locations it is recommended that a probability sampling design be utilized, preferably the systematic-aligned grid method, and as a minimum first-order estimate about 1 1 samples should be collected for inventory estimates. '. '

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Section: Introductionmentioning

confidence: 93%

Caesium-137 soil sampling and inventory variability in reference locations: A literature survey

Sutherland

1996

Hydrol. Process.

143

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“…Long-standing efforts to determine average erosion rates across agricultural landscapes involve the construction of small-scale runoff plots (Roels, 1985), monitoring of suspended sediment concentrations in streams draining the landscapes (Steegen et al, 2001), and, with recent analytical breakthroughs, through the use of sediment tracers (Matisoff et al, 2001) or short-lived isotopes (Matisoff et al, 2002a,b). Collection and analyses of soil from runoff plots or suspended sediment analyses remains problematic primarily because of the difficulties with ensuring a closed system, while injection of tracers onto agricultural lands immediately imparts a short-term measurement bias.…”

Section: Introductionmentioning

confidence: 99%

Quantifying sediment transport across an undisturbed prairie landscape using cesium-137 and high resolution topography

2006

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“…Plot erosion rates were very variable, both spatially and temporally. The data in Table 2 highlight the variability of erosion rates and the difficulty in quantifying meaningful averages (Roels, 1985;Walling & Quine, 1991). Much of the variability is explained by the changeable nature of rainfall erosivity and by plot characteristics (soil organic content and slope angle).…”

Section: Methodsmentioning

confidence: 99%

Erosion rates on bare loamy sand soils in east Shropshire, UK

Fullen

1992

Soil Use and Management

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Abstract. Results from over seven years of monitoring of erosion rates on bare arable loamy sand soils at the Hilton experimental site, Shropshire, UK, are reported. On bare plots, rates are very variable; erosion during one summer convectional storm exceeded that recorded during six individual years of plot measurement. Exposure of erodible arable soils to convectional storms puts them at risk of excessive erosion. Plot erosion rates were frequently high, with rates up to 67.4 t/ha occurring during an individual storm. Rates were influenced by rainfall erosivity, slope steepness and soil organic content. Mean soil organic content on the bare plots decreased over five years by 0.08%/yr.

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Estimation of soil loss at a regional scale based on plot measurements—some critical considerations

Cited by 37 publications

References 2 publications

Caesium-137 soil sampling and inventory variability in reference locations: A literature survey

Caesium-137 soil sampling and inventory variability in reference locations: A literature survey

Quantifying sediment transport across an undisturbed prairie landscape using cesium-137 and high resolution topography

Erosion rates on bare loamy sand soils in east Shropshire, UK

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