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:: 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:: 2 Microwave data. Chairman: N. Lannelongue, Liaison: L. Krul

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Detection by side-looking radar of geological structures under thin cover sands in arid areas. B. N. Koopmans

Document type:: Multivolume work

Structure type:: Chapter

Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 149 Detection by side-looking radar of geological structures under thin cover sands in arid areas B.N.Koopmans International Institute for Aerospace Survey and Earth Sciences (ITC), Enschede, Netherlands ABSTRACT: Images of SIR-A and SIR-B shuttle radar have been studied for penetration capability of the micro- waves in arid areas. In the Red Sea hills (Sudan), the radar information was compared with Landsat Images and Large Format Camera (LFC) photos. Particularly on the latter, much detail could be obtained through stereo analysis. A radar strip over the central Iranian desert was compared with hand-held shuttle photography. In both Sudan and Iran it appeared that the radar images revealed some information of the bedrock in the sandy areas otherwise not visible on the images obtained in the visible or near infrared part of the spectrum, indicating a certain penetration capability of microwaves through thin cover sands. The differences between "dike lineament" interpretation on radar image and LFC photos are not so much influenced by the penetration capability of microwaves, but much more by the influence radar look direction has on the enhancement or de preciation of lineaments. INTRODUCTION The proportion between the contribution of surface scattering and that of volume scattering towards the radar return signal in a side-looking radar survey is still much subject to study and discussion. It varies with radar variables (wavelength and polari zation) and flight configuration (incidence angle), but is also dependent on the target variables such as surface roughness and dielectric properties of the target material. The practical question is can we learn how much of the backscattered received energy comes from surface scattering and what part is contributed by volume scattering, and, if volume scattering is present, how deep will the energy penetrate to give a still detectable return signal of a subsurface interface between two different materials. Translated towards the field of application in geology, the question is will microwave remote sen sing give some information on geological structures or rock formations which are lightly covered, for example by windblown sands or superficial soil cover. This question may be of great importance to many geologists working in desert-like environments where a thin sheet of aeolien sand may cover vast tracks of rock formations and obscure the tectonic structures. Studies with microwave remote sensing in areas under hyperarid conditions have revealed that buried channels may be detected (Breed et al., 1983). McCauley et al. (1982) demonstrated that from the Shuttle Imaging Radar (SIR-A) images, buried valleys and geological structures could be detected under light sand cover of the Salima sand sheet in Egypt. The actual penetration depth was found to be in the order of 1 m for the sand sheet and about 2 m for the dry sand dune areas. On the basis of samples taken in the field and their dielectric parameters measured in the labora tory, a theoretical depth penetration of 6 m was derived. The discrepancies between the actual measured and the modeled depth penetration is principally a re sult of the difficulty defining parameters effecting volume scattering of the inhomogeneous medium between the surface and subsurface interface. The roughness and orientation of the subsurface inter face will affect further the angular backscattering pattern at depth. Rebillard and Ballais (1983) reported penetration of microwave energy through a thin sheet of drift sand 10-15 cm thick in the Algerian Bas-Sahara. To study empirically if sand-covered geological structures could be detected on side-looking radar images, a comparative study was made of SIR images with other remote sensing data such as Landsat, Large Format Camera (LFC) and space photos of arid areas in Iran (Dash-e-Lut) and Sudan/Egypt (Red Sea hills and eastern desert). CENTRAL IRAN A shuttle imaging radar strip (SIR-A) over central and eastern Iran was compared with Landsat images and shuttle hand-held space photography over the same zone. Particular attention was paid to possi ble differences in the desert-like sandy areas, where geological structures may be covered by thin aeolian sand sheets or colluvial bahada material. The area under consideration is classified as arid. The meteorological data of the Nehbandan station (32°20'N, 57°35'E), situated about 150 km south of the radar strip, give a mean annual preci pitation of 100 mm/year. The dry period is from June to November when precipitation is negligible. December and especially January are the wetter months, when local heavy showers give an irregular rainfall distribution. The SIR-A images were ob tained towards the end of the dry period on 14 November 1981, making penetration in the dry areas more likely. The Shuttle Imaging Radar had a frequency of 1.28 GHz (L band 23.5 cm), HH polarised. The depression angle of the radar was 43 degrees, ± 3°. By carefully scrutinizing data take 35-36, an E-W strip which runs over the Dash-e-Kavir and Dash-e- Lut, it was noticed that in an area south of the village of Esfideh (33°36'N, 59°40'E) in the pro vince of Horasan (east Iran), two strike ridges appear over much longer distances on the radar image than on the hand-held space photo (fig. 1A and 1B between a and b). According to the geological map of Iran (National Iranian Oil Company, 1959) the age of the outcrop ping rocks is Eocene to Oligocene. In the Dash-e- Lut area, rocks of this age are principally of a terrestric nature. The two strike ridges appear as well-defined horizons with a white color on the

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