摘要:

ABSTRACT:Rainfall simulator studies were conducted during 1982 and 1983 on agricultural and native rangeland soils of the same soil series in northern Utah. Results indicate that the same soil series mapped at different locations on agricultural land will have similar 10, 20, and 30 minute infiltration rates and similar interrill erosion rates. Seasonal differences in infiltration and erosion rates were significant. Comparisons between agricultural and native soils were complicated by three‐way statistical interactions. Seasonal variations in both infiltration rates and erosion rates were greatest on agricultural soils. Of four soil series on native rangeland, only one showed significant seasonal variation in infiltration rates, while erosion rates were similar across all seasons for all soil series. Soil and cover factors important in predicting infiltration and erosion were identifie

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb00893.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:A hypothetical, although realistic, water pollution problem was studied from a property rights viewpoint. Theoretical and economic justifications were developed. A fully‐liable, private owner was found to be financially profitable while improving the water quality and providing recreational potential. The example confirmed that property rights provides an answer to stream pollution problems, but contradicted the view that water pollution control must be justified by recreational benefit

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb00894.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT:Southeast Asian nations with extensive water management systems have numerous candidate and ongoing programs and projects. They cannot possibly all be funded and implemented simultaneously in any serious way. Choices must be made. But how to select? What criteria can assist with the screening in an acceptable manner, particularly in the near absence of useful technical and economic information across them all. This paper suggests a methodology by which assessment criteria can be constructed which conforms to any given national information base and development needs. Criteria can be weighted one against the other in their relative importance. For each criterion a ranking scale puts the “best” (most, highest) at one end and the “worst” (least, lowest) at the other. Each candidate project is then subjected to these consistent assessment methods for a weighted “score.” Key criteria normally have surrogate measures depending on information available. Criteria are of three sorts: sheer volume, e.g., of a specific use, a benefit; ratios and relations, e.g., A as percent of B; and other more subjective criteria, e.g., regional or income distribution impacts. The basic criteria include, for example, time to full benefits (minimize), OM&R as percent of investment (minimize), and permanent rural jobs created

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb00895.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SUMMARYMontgomery and Loftis (1987) have listed several situations for which the t‐test does not accurately reproduce Type I errors, and should therefore be avoided. Characteristics common to water quality data (skewness or other non‐normality, presence of outliers and less‐thans) also reduce the power of the t‐test, in relation to nonparametric alternatives.Thus if one is interested in reaching correct decisions when trends or differences exist, and not just when they do not, the t‐test should not be considered “robust” (in the sense of being generally applicable) when its assumptions are violated. Further, t‐tests assume that differences in means are relevant (the mean is a good measure of central tendency), and that data groups differ by some additive amount. When all of these assumptions are recognized, and in light of the availability of truly robust and comparatively powerful non‐parametric alternatives, we believe there is little applicability of the t‐test for detecting trends or differences in wate

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb00896.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1988.tb00897.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY