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

damen, m. c. j.

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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:: 856641294

Title:: Remote sensing for resources development and environmental management

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

Scope:: IX Seiten, Seiten 551-956

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A,. A. Balkema

Identifier (digital):: 856641294

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,2)

Language:: English

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

Editor:: Damen, M. C. J.

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

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:: 6 Hydrology: Surface water, oceanography, coastal zone, ice and snow. Chairman: K. A. Ulbricht, Co-chairman: Mikio Takagi, Liaison: R. Spanhoff

Write comment:: Wegen zu enger Bindung kommt es teilweise im Original zu Textverlust.

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Classification of bottom composition and bathymetry of shallow waters by passive remote sensing. D. Spitzer & R. W. J. Dirks

Document type:: Multivolume work

Structure type:: Chapter

Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 775 Classification of bottom composition and bathymetry of shallow waters by passive remote sensing D.Spitzer & R.W.J.Dirks Netherlands Institute for Sea Research, Den Burg, Texel ABSTRACT: Reflectance of solar radiation contains information about the composition of the watercolumn as well as about the bottom in areas where the visible light penetration depth exceeds the bottom depth. When the mapping .of the bottom depth and composition is pursued, specific algorithms must be developed in order to remove the influence of the watercolumn on the upwelling optical signals. Calculations were performed relating the reflectance spectra to the parameters of the watercolumn and of the diverse bottom types. Measurements of the underwater reflection coefficient of sandy, mud and vegetation-type seabottom were performed. Two-flow radiative transfer model was employed, where the spectral signatures of suspended and dissolved materials and of the bottom were introduced as the input parameters. Several algorithms are proposed with respect to the application of Landsat MSS, TM and SPOT HRV scanners. Bottom depth and features appear to be observable down to 3-20 m, dependently on the water composition and bottom type. RESUME: La reflexion diffuse du rayonnement solaire détient des informations sur la composition de la colonne d'eau ainsi que sur le fond de la mer dans des zones où la profondeur de pénétration de la lumière visible excède la profondeur du fond. Pour dresser la carte de la profondeur du fond et de sa composition il nous faut des algorithmes capables d'éliminer l'influence de la colonne d'eau sur les signaux optiques ascendents. Des calculs ont été faits pour estimer le rapport entre les spectres de réflexion diffuse avec les paramètres de la colonne d'eau et des catégories diverses du fond. Des mesures de la réflexion diffuse dans l'eau ont été effectuées sur des fonds de catégorie sableuse, boueuse et végétative. Le modèle de transfert radiatif des deux flux a été utilisé, dans lequel les signatures spectrales des substances dissoutes, des matières en suspension et du fond ont été introduit. Plusieurs algorithmes ont été proposés en rapport avec l'application de Landsat MSS, TM et SPOT HRV scanners. La profondeur et composition du fond se trouve détectable jusqu'à 3-20 m, selon la composition de l'eau et de la catégorie du fond. 1 INTRODUCTION In shallow waters and tidal areas solar radiation transmitted by the water layer and reflected by the bottom can substantially contribute to the upwelling -optical signals. When appropriate absorption and backscattering signatures (coefficients) of both, the waterlayer and of the bottom, are introduced into a rigorous radiative transfer model, the contribution of the bottom reflectance can be evaluated and used for the remote determination of the bottom depth and type. Spectral despendence of all the optical coefficients must be accounted with respect to the spectral characteristics of the remote (satellite or air borne) sensors. Recent investigations on the optical properties of the watermasses and on the radiative transfer in natural waters, generally initiated by the development of modern remote sensing techniques, allow calculation of the up welling spectral radiance and hence establishment of useful algor ithms for bottom depth and bottom and watercolumn composition mapping. Two-flow radiative transfer model in its reflectance form is used in this paper, with as boundary condition the (wavelength dependent) bottom reflectance. Variable concentrations of chlorophyllous and non-chlorophyllous particulate and organic dissolved materials are accounted as well as various types of the sea bottom. Reflectances within the spectral bands of the Landsat Multi- Spectral Scanner (MSS), Landsat Thematic Mapper (TM), SPOT High Resolution Visible (HRV) and the TIROS-N series Advanced Very High Resolution Radiometer (AVHRR) were computed in order to develop appropriate algorithms suitable for the bottom depth and type mapping. Ground resolution (20-80m) of the Landsat and SPOT instruments is more suitable for the coastal mapping purposes than the resolution of the Coastal Zone Color Scaner (CZCS, 800 m) and of the AVHRR (1100 m). However, the wide accessibility of the AVHRR data makes also this sensor attractive when large scale mapping is pursued. The orbital repeat cycles of Landsat and SPOT (16-26 days) are sufficient for observation of long term bottom depth and composition variability. Linearity and high sensitivity of the algorithms for the quantities to be detected is desired along with low sensitivity of the other parameters. 2. TWO-FLOW RADIATIVE TRANSFER MODEL Upwelling radiance measured by the remote optical sensors is proportional to the reflectance R. The reflectance dependence on the depth z and wavelength X can be described by the radiative transfer equation dR(z, - X j- = - b (X) + (a (z)+b (z)+a,(z)+b,(z)) R(z,X) dz d u u d d -b 2 (z)R 2 (z,X) u where a , a^ are the absorption coefficients for the upwelling and downwelling irradiance res pectively, and analogously b u , b^ are the back- scattering coefficients. For shallow waters, where the light penetration depth exceeds the bottom depth, the boundary condition R(h,X) = r(X),

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