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Title: SCALE ISSUES

Author
item LOAGUE, KEITH - STANFORD UNIV. CA
item Corwin, Dennis

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 1/5/2006
Publication Date: 7/20/2006
Citation: Loague, K., Corwin, D.L. 2006. Scale issues. In: J. Delleur and J. Cushman (eds.) Groundwater Engineering Handbook. CRC Press, Boca Raton, FL. 25.1-25.21.

Interpretive Summary: Scale has a profound influence on earth scientists’ ability to develop models that describe systems related to hydrology, agriculture, and the environment. Whether one is engaged in laboratory or field experiments, modeling, or measuring parameters for models, scale is an important consideration. Currently, scale is one of the most challenging yet critical issues for hydrologists and soil scientist to understand in order to conceptualize hydrological processes. This chapter in The Handbook of Groundwater Engineering introduces the subject of scale as it relates to hydrology. The chapter contains a brief background with respect to the relationship of scale and hydrological processes, measurement and interpretation of scale, upscaling and downscaling, and finally two examples. From this chapter soil scientists and hydrologists who are less familiar with the influence of scale on hydrological process will gain an understanding of scale that will provide them with an awareness and appreciation of the difficulties in taking studies at the small scale of the laboratory and bringing them to practical applications at field scales and larger.

Technical Abstract: One of the many definitions for scale in Webster’s dictionary is a system of grouping or classifying in a series of steps or degrees according to a standard of relative size, amount, importance, perfection, etc. The jargon used to describe scales in earth science includes, for example, continuum, correlation, integral, microscopic, macroscopic, local spatial average, REA (representative elementary area), and REV (representative elementary volume). The objective of this chapter is to introduce the subject of scale as it relates to hydrology, the entirety of which could easily fill several volumes. The chapter contains a brief background with respect to the relationship of scale and hydrological processes, measurement and interpretation of scale, upscaling and downscaling, and finally two examples involving (i) alternative characterizations of spatial variability at the catchment scale and (ii) extrapolation from site to region. Though formidable, the vicissitudes of scale influences on hydrological processes is among the most challenging yet critical issues for hydrologist and soil scientists to address.