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:: 856662364

Title:: Remote sensing for resources development and environmental management

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

Scope:: VI, Seiten 959-1074

Year of publication:: 2016

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856662364

Signature of the source:: ZS 312(26,7,3)

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:: Invited papers

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Approaches to monitoring renewable resources using remote sensing and geographical information system. Lennart Olsson

Document type:: Multivolume work

Structure type:: Chapter

Symposium on Remote Sensing for Resources Development and Environmental Management/Enschede/August 1986 © 1987Balkema, Rotterdam. ISBN 90 6191 674 7 Approaches to monitoring renewable resources using remote sensing and geographical information system Lennart Olsson University of Lund, Sweden ABSTRACT: The report is aimed at introducing various remote sensing methodologies for the study of renewable resources. Different aspects of vegetation monitoring, including topics like supply/demand of natural resources and mapping of erosion hazards. The emphasis is put on applications of available satellite sensing systems on vegetation monitoring in developing countries. 1. INTRODUCTION "...we are nowhere near to achieving the ultimate capability of the space vantage point for delivering useful information to the user. The information which such systems can produce is of immense economic, sociological and humanitarian value" (Landgrebe 1983). This is very much true for the present sub ject, remote sensing of renewable resources. The term renewable resources is difficult to define explicitly. In this paper I have restricted the defi nition to cover different aspects of vegetation, but included some related fields, like land degradation (e.g. soil erosion and desertification). The emphasis will be put on applications of the most commonly used satellite systems, Landsat, NOAA and SPOT, on res ource monitoring in the tropics. A very important development of remote sensing is the geographical information system (GIS) and related technigues, which will be treated as well. 2. REMOTE SENSING OP VEGETATION, AN OVERVIEW Remote sensing uses radiation in different parts of the electromagnetic (EM) spectrum as carrier of information regarding various phenomena on the earth and in the atmosphere. The EM spectrum ranges from X- rays to radiowaves, but only fractions of the spectrum have so far been used for remote sensing applications. Visible and reflected IR radiation is the most freguently used part of the EM spectrum, see Figure 1. However, research aiming at widening the range of wavelengths used for remote sensing is important. 2.1 Visible and reflected infrared radiation Remote sensing by means of photographic technigues in the visible part of the electromagnetic spectrum (0.4 -0.7 microns) have been used for a long time, though primarily for other applications than vegetation studies. The development of IR-sensitive film was initiated in 1931 (Reeves 1975). Although it was originally developed for military purposes, the main use has been within the field of vegetation studies. Among the earliest civilian remote sensing applica tions, were studies of vegetation type and stress (Colwell 1956). The introduction of electro-optical imaging sensors opened up a wider part of the EM spectrum. The research and applications have, however, mainly been restricted to the visible and the near infrared part of spectrum, see Table 1. In the early days of multispectral analysis of vegetation, much research was aimed at determining spectral signatures of different vegetation species. It soon became obvious that the concept of unique spectral signatures did not hold. Hence, it is very unlikely that automatic classification on board the satellite suggested by Ewalt (1979), will be reali zed. But the assumption of spectrally unique signa tures is still considered acceptable by many authors, when applying multispectral classifications, see section 5.1. An important feature of the visible and near infrared radiation is the relationship between reflectance and green vegetation, see Table 2. The combination of strong negative correlation with vegetation amount in visible red and the strong positive correlation in near infrared can be used for quantifications of vegetation amounts. The introduction of new wavelength bands with the Thematic Mapper sensor of Landsat 4 & 5, made some interesting parts of the spectrum, in the near infra red part, available to satellite remote sensing, the bands 5 and 7 (Figure 1 and Table 1)\. The reflectance from vegetation in this part is mainly controlled by the water content./ In combination With the shorter NIR and visible bands, we cah expect new possibilities for assessing vegetation'' conditions. 2.2 Thermal infrared radiation All objects warmer than -273 C emit electromagnetic radiation, where the wavelength is dependent of the temperature of the object. The radiation emitted from the surface of the earth is typically in the range of 3-50 microns. Remote sensing devices recording this radiation can be used to measure the radiating temperature of objects. However, to determine the actual temperature of an object, we must know the emissivity of the surface we are sensing, and this is a major constraint to the use of thermal sensors in remote sensing. Natural surfaces have typical emissivity values between 0.90 and 0.99. To determine actual temperature to an accuracy of 1C, an accuracy of 0.02 of the emissivity is required (Slater 1980). Most important remote sensing platforms for thermal IR sensors have been, and still is, meteorological satellites e.g. NOAA, SMS/GOES, and Meteosat. Other platforms are HCMM (Heat Capacity Mapping Mission 1978-80), Seasat (1978) and the Landsat 4 & 5 band 6 of the Thematic Mapper sensing system. For a review of thermal infrared remote sensing from satellite see Lynn (1986). The literature on the use of thermal IR imagery for vegetation studies is, compared to visible and NIR, scanty. There are several reasons to this: 1041

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