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

damen, m. c. j.

Bibliografische Daten

Mehrbändiges Werk

Persistenter Identifier:: 856342815

Titel:: Remote sensing for resources development and environmental management

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

Erscheinungsjahr:: 1986

Erscheinungsort des Originals:: Rotterdam; Boston

Verlag des Originals:: A. A. Balkema

Identifier (digital):: 856342815

Sprache:: Englisch

Sonstige Anmerkungen:: Volume 1-3 erschienen von 1986-1988

Herausgeber:: Damen, M. C. J.

Dokumenttyp:: Mehrbändiges Werk

Band

Persistenter Identifier:: 856641294

Titel:: Remote sensing for resources development and environmental management

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

Umfang:: IX Seiten, Seiten 551-956

Erscheinungsjahr:: 1986

Erscheinungsort des Originals:: Rotterdam; Boston

Verlag des Originals:: A,. A. Balkema

Identifier (digital):: 856641294

Illustrationsangabe:: Illustrationen, Diagramme

Signatur der Quelle:: ZS 312(26,7,2)

Sprache:: Englisch

Nutzungslizenz:: Attribution 4.0 International (CC BY 4.0)

Herausgeber:: Damen, M. C. J.

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

Verlag des Digitalisats:: Technische Informationsbibliothek Hannover

Erscheinungsort des Digitalisats:: Hannover

Erscheinungsjahr des Digitalisats:: 2016

Dokumenttyp:: Band

Sammlung:: Geowissenschaften

Kapitel

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

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

Dokumenttyp:: Mehrbändiges Werk

Strukturtyp:: Kapitel

Kapitel

Titel:: A study with NOAA-7 AVHRR-imagery in monitoring ephemeral streams in the lower catchment area of the Tana River, Kenya. J. W. van den Brink

Dokumenttyp:: Mehrbändiges Werk

Strukturtyp:: Kapitel

784 3 METHODS. Table 1. Band width of the NOAA-7 AVHRR system 5 CONCLUS 3.1 Outlines The contribution in waterflow of 90 smaller and larger Laga's is an unknown factor, which is difficult to analyse given the vastness and inacessibility of the lower catchment area (55,000 km 2) and the ephemeral character of the outflow. To measure and monitor the flow in these Laga's in the field or even from the air in a systematic way is an operation which involves huge means in terms of logistics and manpower, and is therefore outside the scope of this study. A study methodology principally based on the use of satellite remote sensing techniques offers in fact the only way to obtain data of the area in a systematic way. Because of the dynamic nature of the Laga system a satellite monitoring program during the two rainy seasons in may-june and october-december in 1984 seems to meet best the objectives. 3.2 Selection of satellite imagery The satellite systems available for civilian use and capable of imaging the area whith regular intervals are the Landsat system and the systems based on meteorological satellites. The current Landsat satellite passes over the area whith an interval of 16 days. Only on few occasions Landsat data of the area are being collected, while there also is a great chance that the area is hidden for the satellite behind the clouds during the time of observations. Since Landsat data do not offer a reasonable possibility for the collection of a satisfactory amount of data during the cloudy seasons, the study relies on imagery provided by the meteorological satellites. Among the remote sensing instruments on board of the various meteorological satellites the Advanced Very High Radiometer (AVHRR) on board of the American satellite NOAA-7 offers the best possibi lities given its characteristics in spatial and temporal resolution (described in detail in section 3.3.). Use is made of of the Local Area Coverage programme (LAC) for the acquisition of the NOAA satellite data. In this programme user request NOAA-7 AVHRR data is recorded onboard the satellite for subsequent playback as Local Areal Coverage (LAC) data. 3.3 The AVHRR system on board NOAA-7 The American NOAA-series of polar orbiting envi ronmental satellites became a more interesting source for studying vegetation since the launch of the NOAA-6 satellite in june 1979. An improved sensor, the Advanced High Resolution Radiometer (AVHRR) was since then added to the basic confi guration of the NOAA-satellites. The main features of interest for studying vegetation with the AVHRR system are the high temporal, near daily revisit of any given place on earth, associated with an increased spatial resolution of 1.1 km at nadir, a +/- 56 csan angle and a swath width of 2700 km. The AVHRR system on board of NOAA-7, from which the imagery for this study was obtained, records in 5 channels. The band width of these channels are presented in table 1. 3.4 Ordering of N0AA-AVHRR imagery DHV requested NOAA/NESDIS to collect NOAA-7 AVHRR imagery through the Local Area Coverage(LAC) program during two periods of two months (May-June) and three months (October-December) in 1984. Quick-looks of the best two images of each week were produced by NESDIS. From these hard copies Channel Bandwidth (urn) 1 .58 - .68 2 .725 - 1.10 3 3.55 - 3.93 4 10.5 11.3 5 11.5 12.5 DHV selected the images suitable for digital processing. Unfortunately clouds were always present over the study area during the first period of observation. Only two images of May 3 and June 20, with a relatively low cloud cover were worth digital processing. The digital tapes of these two dates were ordered for further inves tigation. During the second period of observation, data of only four heavily clouded days were archieved despite NOAA's adequate mission planning. So no suitable images for digital processing were made available during this second period of obser vation. 3.5 Image processing The image processing facility at the Research Institute for Nature Management (RIN) was used for the processing of the NOAA tapes. The digital image processing routines that were used consist merely of image enhancements in order to obtain an optimal visual representation. Also the normalized difference images : (c2-cl)/(c2+cl) of the near- infrared and red channel resp. channel 2 and 1, (according to C.J.Tucker,1984) were calculated for both days. According to this author this so-called biomass index was presented as a succesful variable which correlate well with the green leaf biomass of vegetation. Consequently no atmospheric corrections were deemed necessary. 4 RESULTS. Due to the presence of severe cloud cover especially above the catchment area only parts of this area could be observed satisfactorily on the imagery of both days. Therefore no systematic analysis on the hydrologic influence of the Laga's on the Tana River could be made. However, despite this severe obstruction the image ry shows that a considerable vegetation growth took place along the upper reaches, especially in the swamp areas, of the larger Laga's. No significant vegetation growth along the lower reaches of the larger Laga's and the other Laga's could be observed. Given the morphology of the Laga's as visible on Landsat-imagery, this indicates that no significant outflow from the Laga's took place during the period of observation. The biomass image of May 3 shows consistently higher values of the biomass index in comparison with the biomass image of June 20. These observa tions are in accordance with the field observa tions and are caused by the fact that the only rains of this first rainy season of May-June fell in the period prior to May 3. Although the N0AA-AVHRR system is especially suited for inventory of large areas, it can be concluded from the imagery that it offers suffi cient detail in spatial and radiometric resolution to observe and monitor vegetation growth of small regions, like the area along the Laga's. During a sible to the N0AA- revisit c cover, wh River reg optical s practices like rada as the ti world. Despite t indicate monitorir regions. sufficier no atmosj imagery t the fielc REFERENCE Blyth, K. Report Walling Colwell,E vol. 1 grammet Deutsch, Satelll Associa DHV Const microli photogi DHV Const measure aerial DHV Const Tana Ri morpho] DHV Const riments ephemei DHV Const Study 1 Nether] Donker, I process ITC, tl Lillesanc and im< NOAA p< Depart« mental Tucker, ( Engine« tation imager]

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