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

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Shuttle Imaging Radar (SIR-A) interpretation of the Kashgar region in western Xinjiang, China. Dirk Werle

Document type:: Multivolume work

Structure type:: Chapter

188 directions cause 'chinook' effects during the winter season. In the Tarim Basin, sand storms frequently occur during the spring and summer months (USSR Academy of Science 1969, Petrov 1976). The floral composition is controlled exclusively by xerophyte and halophyte species. Although the vegetation cover is very sparse in general, concentration and diversification occurs in the oases, e.g. various species of poplars, willows, tamarisk, saksaul and thickets of reed and camel thorn (USSR Academy of Science 1969). Geologically, the formation of the Tarim Basin dates back to the late Paleocene. Upper Cretaceous, Eocene and early Pliocene sedimentary rocks are largely covered by Quaternary aeolian sand dune fields and are only exposed as gently folded sequences along the margins of the basin. The boundary of the foothill zone towards the Pamirs is composed of a series of alluvial fans. The eastern Pamirs consist of a system of NNW-SSE as well as E-W striking chains and intermontane depressions. Ordovician, Silurian, Devonian, and Paleozoic rocks formations were subjected to faulting and uplift during Cenozoic times (Geological Map of China 1:2,500,000, 1976). A significant portion of the eastern Pamirs, i.e Mount Kongur (7,719 m), Mount Muztaghata (7,546 m), and the Kingata Range (6,700 m) are exposed to high altitude westerly winds and precipitation. Approximately 60 glacier fields cover an area of 596 km 2 (Wiens 1966) with firnlines being confined to elevations between 5,600 and 5,700 metres (Freeberne 1965, Field 1975, Shi and Yang 1985). The moisture accumulated in these snow fields and glaciers is partially released during the melting season. Since neither the annual nor the seasonal precipitation meet the water requirements for crop cultivation, the Kashgar oases have been and still are entirely dependent on the discharge of meltwater for irrigation purposes. The area is part of the cotton-sericulture and two year tripple cropping wheat and corn region of western Xinjiang, supporting a population of more than 2.3 million people within the administative district of Kashgar. KASHGAR 1306m, 11.6'C , 63r T X \ / \ / , / \ -40 ■20 n MM 1 MELT SEASON—} JFMRMjjflSOND WR in mm 1000-1200 450 - 525 CORN » — 375 - 450 COTTON - 600 - 750 Figure 2. Climatic diagram for Kashgar, Xinjiang. (T = Temperature, in °C; P = precipitation, in mm) and water requirements (WR, in mm) for cultivation. 3 THE SIR-A SYSTEM The system configuration and first results of the SIR-A experiment were presented by Cimino and Elachi (1982) and Ford et al. (1983). The space shuttle orbited the earth at an altitude of 259 km, at an inclination of 39°. During the mission the imaging radar directed a microwave beam at a wavelength of 23.5 cm (L-band) toward the earth surface at a depression angle of 40°. In flat terrain, this results in an incidence angle of 50° (Figure 3) and varies accordingly with different slope angles and slope orientation. The backscattered energy from the earth surface is received by means of an antenna. The capability of radar to penetrate cloud cover avoids dépendance on diurnal time and weather conditions. Following the mission the signal film which contained a record of the radar returns in holographic form was optically correlated to produce the actual image. The SIR-A swath width covers an area of 50 km on the ground. The spatial resolution is 38 metres in azimuth as well as in range direction. Figure 3. The SIR-A system and viewing geometry. 4 RADAR INTERACTION WITH TERRAIN The energy of the radar return signal from the terrain to the antenna is a function of the radar system configuration, its viewing geometry and the terrain properties such as dielectric constant, topography, surface roughness, and vegetation cover. The resulting backscatter coefficient is generally expressed on the image either in terms of magnitude, i.e. image tone, or spacial variability, i.e. image texture (Ulaby 1982, Evans et al. 1986). The complex dielectric constant is a measure of the electrical properties of natural material upon incidence of electromagnetic energy. Variations in the return of the radar signal may be determined by the actual moisture content of the rock, soil or vegetation. Under very arid conditions signal penetration of sand and soils may be considerable until refraction at a major dielectric discontinuity surface such as sand covered bedrock occurs. The influence of the dielectric constant, however, is often masked by the effects of topography and surface roughness. Expression of surface morphology is defined by the orientation of terrain and the illumination geometry of the radar. Slopes facing the radar look direction produce strong returns and bright image signatures. Slopes oriented away from the radar at an angle exceeding the depression angle result in radar shadow, i.e. no energy return. Apparent displacement or layover of mountain tops toward the radar antenna occurs where the curved front of the radar signal encounters the summit of a topographic feature first before reaching its base. Roughness refers to relative surface irregularities measured in dimensions of centimetres, and is dependent on the radar wavelength and incidence angle (Rayleigh Criterion). At L-band (SIR-A) a flat surface with less than 1.5 cm of surface roughness appears smooth and without appreciable scattering, since the signal is reflected at an angle equal and opposite to the angle of incidence. The resulting radar signature is dark. Surfaces with an intermediate roughness of 1.5 cm to 8.3 cm disperse the incident energy and produce a scattering response and intermediate grey signatures on the image. A surface is considered rough when local relief is greater than 8.3 cm. In this case, a relatively high amount of antenna image. Vegetat tone on extremely complex physionom propertie influence discontin the vol electric the targ dielectri 5 IMAGE The SIR-A 1) focuse regions, visual such imag context, scale overlays (A-7), re The ana made duri extracted (0NC, G-7 1:2,500, literatur Table 1. 1 SANDY DESERT 2 ALLUVIAL PLA Floodplains Sand Dunes 3 ALLUVIAL FAN Floodplains Old Terraces Snovfields Glaciers '^Boundary: + + ■ very sh, - - - transit 5.1 Physl On the SI various and grot regions I SW-NE d: moderate! and the ! A unifc part of 1 as a mai formatioi indicatii absorbed As a resi ragged 1 partially Medium

Access restriction

Copyright

fullscreen: Remote sensing for resources development and environmental management (Volume 1)

Multivolume work

Volume

Chapter

Chapter

Table of contents

Cite and reuse

Volume

Chapter

Image

Image fragment

Citation links

Citation recommendation