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

lergy from the an antenna, t cloud cover and weather signal film r returns in :ed to produce ith covers an 'al resolution as in range geometry. lal from the of the radar netry and the ric constant, station cover, is generally of magnitude, f, i.e. image ). neasure of the naterial upon Variations in determined by rock, soil or itions signal considerable discontinuity occurs. The , however, is hy and surface defined by the ation geometry look direction ge signatures. at an angle ult in radar t displacement radar antenna radar signal feature first irregularities res, and is ncidence angle IR-A) a flat face roughness e scattering, ngle equal and The resulting :es with an 1.3 cm disperse :ering response the image. A ical relief is elatively high amount of radar backscatter is received by the radar antenna resulting in light grey signatures on the image. Vegetated areas appear rough and hence in bright tone on the SIR-A image. They are considered as extremely diffuse scattering surfaces due to their complex geometric characteristics, i.e. plant physionomy, but also because of their electrical properties. Geometrical characteristics which influence the radar backscatter include roughness and discontinuities at the plant canopy itself and within the volume, e.g. foliage and branches. The electrical properties of vegetation are a function of the target permittivity and conductivity, i.e. the dielectric constant of the biomass. 5 IMAGE INTERPRETATION The SIR-A image analysis of western Xinjiang (Plate 1) focused on the following features: physiographic regions, water supply, and land use patterns. A visual interpretation method was chosen to assess such image elements as tone, texture and geographical context. Thematic maps were produced at an original scale of 1:500,000 using various transparency overlays. Locations mentioned in the text, e.g. (A-7), refer to Plate 1, Figure 4 and Figure 5. The analysis was supported by ground observations made during a field trip in October 1984, by data extracted from topographical and geological maps (0NC, G-7, 1:1,000,000 and Geological Map of China, 1:2,500,000), and by material presented in the literature. Table 1. SIR-A image interpretation chart. PHYSIOGRAPHIC REGIONS & Terrain Categories IMAGE TONE IMAGE TEXTURE BOUNDARY " RELIEF 2 ' Impression DRAINAGE 3 ' TECTONIC pattern/density CONTROL 1 SANDY DESERT dark smooth +/- internal nona 2 ALLUVIAL PLAIN medium fine-grain +/- parallel (1) moderate Floodplains dark-grey smooth + braided (1) moderate Sand Dunes dark smooth + internal n.a. 3 ALLUVIAL FANS medium fine + distrib. (m) none Floodplains light-grey fine-grain + -- distrib. (h) none Old Terraces dark smooth + + + parallel (m) none 4 DENUD. MOUNTAIN & HILL REGION medium/ light-grey fine + + dendritic/ parallel (h) high 5 EROSIONAL HIGH MOUNTAIN REGION dark-grey/ light-grey coarse + + + sub-parallel/ dendritic (m) moderate 6 NIVAL-ALPINE REGION dark/light coarse + + + + sub-parallel/ dendritic (1) moderate Snovfields light fine-grain - - n.a. n.a. Glaciers med./light fine-grain + +/- n.a. n.a. ''Boundary: + + ■ very sharp ^Relief Impression: + + ■ very good ¿ \ ^Drainage density: h - high m “ medium — - ■ transitional - - - none n.a. - not applicable 5.1 Physiographic Regions On the SIR-A image a number of terrain categories and various sub-categories may be recognized (Table 1) and grouped into six major natural physiographic regions (Figure 4). These regions are oriented in a SW-NE direction. A distinct boundary divides the moderately to highly reliefed uplands of the Pamirs and the lowlands of the Tarim Basin. A uniform dark tone and a smooth texture in the SE part of the study area characterize the sandy desert as a marginal part of the Taklimakan Desert. Dune formation or drainage channels can not be identified, indicating that the incident radar energy is largely absorbed by a continuous cover of loose, dry sand. As a result the backscatter signal is very low. The ragged boundary towards the alluvial plain is partially transitional. Medium grey tones and a fine granular texture are the dominant image characteristics of the alluvial plain. Clay, silt and loess deposits which are in part deformed by wind erosion contribute to moderate radar backscattering. Low density and sub-parallel drainage channel sections appear as irregular dark and dark-grey bands (H-10). During the dry season most of the active river channels do not contain water. Their fine-grain sediments and smooth surface morphology produce low backscatter signals. Sporadic alignments of light grey tone and crescent shapes (F-6/7) delineate cliffs of fluvial terraces which act as corner reflectors when oriented towards the radar. The drainage network in the alluvial plain is generally oriented in a E to ESE direction. Small elongated streaks of dark-grey tone mark the present position of various groups of sand dunes (D-4). The dunes are almost exclusively oriented in a SE direction which corresponds well with the prevailing regional wind direction. The most outstanding features within this alluvial plain are linear and rectangualar outlines of the oases. These are dealt with in a seperate section. Along the base of the Pamirs various shades of grey tone as well as smooth and fine-grain image texture suggest different radar backscatter intensities within a zone of interlocked alluvial fans. Their individual delta-shaped outlines and the distributary pattern of the drainage channels are the principal recognition elements on the SIR-A image. Medium-grey, dark-grey and dark tones allow for further subdivision into active channels (G-14), Pleistocene fan deposits (E-13), and older eroded fluvial and/or fluvio-glacial sediments (1-21), respectively. The different grey tone levels probably account for progressive accumulation of aeolian sand or loess deposits on the geneally coarse gravel fans. At the funnel-shaped head of the fans, Quaternary fluvial and fluvio-glacial terraces are frequently undercut by stream erosion during the meltwater season (F-18). The two largest fans within the study area extend over an area of 360 km 2 (F-14) and 380 km 2 (H-16). Gravel bodies such as these have an excellent water storage capacity. The allocation of oases along the foot of the alluvial fans is a clear indicator of the present ground water horizon. The denudational mountain and hill region represents terrain which is highly dissected by a sub-parallel and sub-dendritic drainage pattern. Numerous small valley sections are oriented toward the radar and produce an overall light-grey tone and a fine image texture. Partial coverage of aeolian sediments and the low resistance of the underlying material result in intensive erosion and high density drainage (D-17/18). Tracts of elongated ridges represent more resistant lithologic units (F-17) or hint at folded sedimentary rock structures (B-15). Various linear and partly angular features between this upland area and the lowlands indicate a high degree of tectonic control by a major NW oriented boundary fault (A-14/ H-21) which suffered lateral displacement (G-19). In the erosional high mountain region, topographic relief is expressed in light grey tone where slopes are facing the radar look direction. Slopes oriented away from the sensor appear dark. The moderate to coarse image texture is a function of drainage density which in turn reflects a higher resistance of lithology to erosion compared to the previous region. Crestlines of ridges are irregular and sharp in the eastern portion of the mountain area (G-22/23), whereas higher uniformity charcterizes the Sarikol Mountains (D-28). Accumulation of Pleistocene fluvial and fluvio-glacial sediments occurs in a major NNW oriented intermontane basin (D-26). Its partly dissected terrain has low relief, giving smooth image texture and dark grey tone against which the dark outlines of a lake (D-26/27) barely contrast. Recent floodplains (C-26) appear in lighter tones and a fine granular texture. The NW extension of this tectonically controlled basin, or graben system, suffered lateral displacement in the

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