Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

Bibliographic data

Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: 3 Spectral signatures of objects. Chairman: G. Guyot, Liaison: N. J. J. Bunnik

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Theoretic reflection modelling of soil surface properties. B. P. J. van den Bergh & B. A. M. Bouman

Document type:: Multivolume work

Structure type:: Chapter

331 itification of ea by the use Season. CSIR ,0-6. ng of winter Advances in m analysis of c Engineering matrix theo- emote mapping in of the pro- 8th Interna- ' Environment, estigation of multispectral Distinguish- information. note Sensing. D.W. Deering in the great nposium, NASA F.E. Guertin, ladian LANDSAT natible tape, search Report ntures derived ation. Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 Theoretic reflection modelling of soil surface properties B.P.J.van den Bergh & B.A.M.Bouman Agricultural University, Wageningen, Netherlands ABSTRACT: For a theoretical approach to surface reflection modelling,soil surface properties are divided on two levels of distinct influence on reflection. On the first level, an attempt is made to formulate the influence of particle size, mineralogical composition and moisture content and reflection. The developed equations are ba sed on the Lambert attenuation law of radiation in diffusing media. INTRODUCTION A natural soil surface is a heterogeneous combination of various elements of different composition, size, shape and spatial distribution. The combination of the se elements can be described in terms of soil proper ties such as textural class, mineralogical composition, organic matter and moisture content. Further, a soil surface has a certain roughness. There may be the presence of aggregates, rills, crusts and/or the ef fects of human influence like ploughing or harrowing. Soil surfaces may also contain stones, boulders, plant debris and other materials. Plant life in various forms between algae and trees may be present, while animal activity can have an important impact on the structure of the surface. Finally, this whole com plex of surface elements has a certain spatial orien tation viz: slope and exposition. For a theoretical approach of reflection from a natu ral land surface, a division in two levels of surface properties is suggested. The first will be called "the intrinsic soil surface" and the second the "bare land surface" (the presence of vegetation will not be considered in this study). Modelling reflectance from bare land surfaces The intrinsic soil surface is defined in terms of optical parameters:"a heterogeneous combination of reflective and absorptive elements in a solid, liquid or gaseous state, arranged in a specific spatial dis tribution and orientation. The dimension of these ele ments is such that the reflective process at this intrinsic level is governed by multiple reflections and re-reflections from these elements. The reflec tion from this intrinsic surface is thus the result of multiple internal reflections (mutually influen cing each other) and hence the theory of diffuse re flection should serve as a basis for further theore tical model building. On this level grain size and grain size distribution, shape and frosting of the grains, mineralogy, content and nature of organic mat ter and moisture content should be included as para meters in a model. The bare land surface is defined as a combination of intrinsic soil and non-soil surface segments, arran ged in acertain spatial distribution and orientation. Here, following Cooper and Smith, 1985, only varia tions in reflection arising from macroscopic features of a soil (large enough that diffraction by the irre gularities of the surface may be neglected) are consi dered. A bare soil surface has a certain roughness of many geometrically different intrinsic soil surface segments. Also, non-soil elements like stones and boul ders are included here, as well as slope and exposition of the surface as a whole. Above division in two surface levels is based on the dimensions of the surface elements relative to the re flective processes invoved. By this division, a hier archical ordening in the reflection influencing surfa ce properties is achieved. Modelling of the bare land surface reflection is super imposed on modelling of the intrinsic soil surface reflection. The approach is gra dual in which, started from the skeleton of the soil, different parameters are introduced in the model. In this paper, attention will be paid to modelling at the intrinsic soil surface level only; more specifically to the parameters particle size, mineralogy and moistu re content. THE INTRINSIC SOIL SURFACE At this level, the equation of Lambert-Beer serves as a basis for further elaboration. This equation descri bes reflectance r from diffusing media in the optical range: r = i/l = exp(-kd) eq.l and hence: Ln(r) = -kd eq.2 in which: r = reflectance I = intensity of incident radiation (W/sr/u) I = intensity of reflected radiation (W/sr/ju) k = coefficient of absorption d = mean penetrated layer thickness The coefficient of absorption k is a characteristic of the absorbing components of the medium, while mean pe netrated layer thickness d depends on the geometrical structure and texture of the medium. Both properties are a function of the wavelength of incident radiation. By calculating Ln(r), whereby r is measured for soil samples of different variables, attempts can be made to relate the coefficients k and d to these variables. Since only limited laboratory measurements of reflec tance could be performed, use has been made of measu rements presented in literature. Own laboratory mea surements have been carried out with a NIWARS-spectro- fotometer, measuring bidirectional reflectance in the range of 0.3 to 2.4 ^om. (Bunnik, 1978). The influence of particle size The mean penetrated layer thickness was studied in re lation to particle diameter of sorted soil samples. In 1965, Bowers and Hanks (B&H) published the results of a study to the effect of particle size on reflectance at different wavelengths in the optical range. These reflectance measurements of samples of kaolinite and bentonite clays are used here for further investiga tion, thereby introducing the following two hypotheses 1) d is dependent on wavelength and on particle size 2) k is dependent on wavelength but not on particle size

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