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SK Pathan VK Shukla RG Patel BR Patel KS Mehta 《Journal of the Indian Society of Remote Sensing》1991,19(2):95-112
Proper urban planning and effective implementation requires reliable urban land use statistics. In this context, satellite remote sensing data has been studied using both visual and digital techniques. A portable eight-band radiometer has been used to collect spectral signatures of surface features present in Ahmedabad city and its environs. Using these signatures a suitable approach employing visual and digital techniques has been developed for urban land use/sprawl mapping. Urban land-use maps of Ahmedabad city and its environs were prepared on 1:25,000 scale and for Ahmedabad Urban Development Authority Area on 1:50,000 scale using this methodology. It has been found that edge-enhancement techniques are useful to enhance the contrast among different urban land uses. Classification techniques such as MXL and Bayes classifiers are not successful in discriminating urban land uses. Tonal characteristics alongwith other elements of interpretation are required to classify urban land uses such as residential, industrial etc. Spatial distribution of various urban and uses and the space devoted to each urban land use has been brought out. 相似文献
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To understand the nature of land degradation and factors responsible for it, investigations were carried out in Etah district with an area of 4.45 lakh hectares. For identification of soil/land degradation problems, multidate Landsat, TM spectral bands and FCC were used. It is observed that salt-affected soils are sharply depicted by light and dark gray mixed tone on band 3, while they are not clear on band 4. Flood plain and waterlogged soils are clearly observed on band 4. Band 6 (10.3 – 12.5 µm) helps in separation of broad zones of coarse and fine-textured soils, active flood plain of rivers, and eroded and gullied lands. The confusion between coarse-textured droughty soils and salt-affected areas in TM FCC (2, 3, 4) could be eliminated by use of band-6 data in combination with FCC. For delineation of problematic areas, two approaches were followed viz. (i) physiographic approach, and (ii) direct approach. In the physiographic approach landscape map associated with image characteristics was prepared. Further the image interpretation units were interpreted for land degradation hazards. With this approach physiography and soil relationship and the degradation problems vis-a-vis soil units could be established and ameliorative measures as per soil condition can be suggested. In direct approach, the problematic areas as per predetermined key were demarcated. Out of 4.45 lakh ha of the area, 1.99 lakh ha is affected by various soil degradation problems, like droughty soils, flooding hazard and salinity and alkalinity which cover 22.1%, 50.0% and 27.9%, respectively. To study the distribution of a salt-affected lands, major physiographic boundaries were superimposed over the land degradation map prepared by direct approach. It is observed that 81.5% of the salt-affected areas lie in the old alluvial plain while 18.5% is in recent flood plain. 相似文献
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Estimation of sediment sources using selected chemical tracers in the Perry lake basin,Kansas,USA 总被引：1，自引：0，他引：1
The ability to achieve meaningful decreases in sediment loads to reservoirs requires a determination of the relative importance of sediment sources within the contributing basins. In an investigation of sources of fine-grained sediment （clay and silt） within the Perry Lake Basin in northeast Kansas, representative samples of channel-bank sources, surface-soil sources （cropland and grassland）, and reservoir bottom sediment were collected, chemically analyzed, and compared. The samples were sieved to isolate the 〈63μt m fraction and analyzed for selected nutrients （total nitrogen and total phosphorus）, organic and total carbon, 25 trace elements, and the radionuclide cesium-137 （^137Cs）. On the basis of substantial and consistent compositional differences among the source types, total nitrogen （TN）, total phosphorus （TP）, total organic carbon （TOC）, and ^137Cs were selected for use in the estimation of sediment sources. To further account for differences in particle-size composition between the sources and the reservoir bottom sediment, constituent ratio and clay-normalization techniques were used. Computed ratios included TOC to TN, TOC to TP, and TN to TP. Constituent concentrations （TN, TP, TOC） and activities （^137Cs） were normalized by dividing by the percentage of clay. Thus, the sediment-source estimations involved the use of seven sediment-source indicators. Within the Perry Lake Basin, the consensus of the seven indicators was that both channel-bank and surface-soil sources were important in the Atchison County Lake and Banner Creek Reservoir subbasins, whereas channel-bank sources were dominant in the Mission Lake subbasin. On the sole basis of ^137Cs activity, surface-soil sources contributed the most free-grained sediment to Atchison County Lake, and channel-bank sources contributed the most fine-grained sediment to Banner Creek Reservoir and Mission Lake. Both the seven-indicator consensus and ^137Cs indicated that channelbank sources were dominant for Perry Lake and that channel-bank sources increased in importance with distance downstream in the basin. 相似文献
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