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Research on vegetation change, rangeland assessment or desertification modelling in drylands using remotely sensed image acquisition normally ignores long-term rainfall as a key criterion in image acquisition. This article will present a novel procedure for image acquisition to investigate vegetation change in a degraded rangeland located in Western New South Wales (Western NSW) Australia. Western NSW experienced an unusually prolonged period of rainfall deficit during the 2000s compared to the 1970, 1980 and 1990s. For this purpose, vegetation changes were assessed using Landsat images supported by field survey. The long-term rainfall variability (42-year) was regarded as a key element in image acquisition. Within the timeframe of the 2000s, 2 years with 25 % lower than the 42-year mean annual rainfall were selected. These images were then compared to an image captured in a year (1988) with rainfall closer to the 42-year mean annual rainfall. Two change detection techniques were used, namely univariate image differencing and GIS approaches. Classification of the produced images was pursued based on the digital numbers (supervised) of ground-checked points within the reference image whilst considering the histogram (unsupervised) of each digital number of the produced image. This research emphasized rainfall as a key variable in image acquisition for vegetation change analysis in rangelands. Image acquisition based on long-term rainfall data allowed for the assessment of changes in perennial plant cover by eliminating the effects of extreme rainfall variation on annual grass dynamics and removing extreme reflections caused by their temporary high photosynthetic activity. 相似文献
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During the recent United States foreclosure crisis, investors purchased and leased thousands of homes nationwide, opening up formerly owner-occupied neighborhoods to renters. Yet, little is known about how this process affected regional patterns of residential segregation and inequality. In this study, we combine property-level data on real estate transactions and subsidized housing vouchers from 2004 to 2014 to assess whether the conversion of foreclosures to rentals enabled low-income renters to live in more advantaged neighborhoods in Phoenix, Arizona. Renters with vouchers living in investor-purchased foreclosures were in lower-poverty neighborhoods compared with those not living in investor-purchased foreclosures. This suggests that foreclosure sales may have widened the geography of opportunity for low-income renters with subsidized housing. 相似文献
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Abstract: Coastal research and monitoring on New Zealand beaches have typically examined seasonal and event-driven (storms) changes in the coast. However, historical records are now of sufficient length to indicate that change occurs at longer timescales. This paper presents examples of multi-decadal change at three case-study locations around New Zealand. Results show that morphological adjustment of the coast occurs at multi-decadal scales and is much larger than short-term dynamics. Physical mechanisms driving changes are ill defined but may be associated with El Niños and La Niña episodes which modulate waves and sea level, as well as changes in sediment supply. 相似文献
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Abstract: Understanding coastal boundaries, connections and drivers of landscape change is integral to effective coastal planning and management. This concept is explored here through case studies representing two very different New Zealand systems: embayed sand beaches in eastern and western open-coast settings; and mixed sand and gravel coast river-mouth lagoons. When framed within a resource and environmental management context these studies indicate that national recognition of the dynamic and interactive nature of coastal environments is a relatively new and amorphous phenomenon in New Zealand and, as such, has been ineffective in driving integrated regional management practices and sustainable coastal outcomes. 相似文献
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D. Dragovich 《Environmental Geology》1987,9(3):139-141
The purpose of this study was to establish whether measurements of stone weathering recorded by different observers could
be aggregated into a single data base for evaluating pollution effects on calcareous building stone. Apparent differences
in recorded weathering rates on marble tombstones were here found to be partly a result of lettering size measured, measuring
devices used, and individual observers. 相似文献
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David R. Young George V. Alexander Deirdre McDermott-Ehrlich 《Marine pollution bulletin》1979,10(2):50-56
A number of trace contaminants appear to be introduced to nearshore marine waters as a result of vessel-related activities. Such inputs are clearly reflected by elevated concentrations of these constituents in several tissues of the bay mussel Mytilus edulis. Comparative studies using this bioindicator suggest that harbour-related activities can be as important a source as coastal wastewater discharges in the contamination of nearshore marine ecosystems. 相似文献
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D. Dragovich 《Geoforum》1980,11(2):147-156
An important proportion of Australian dairy production has been destined for export markets, where prices are below those received on the home market. This degree of dependence on international prices has adversely affected dairy farm incomes and thereby influenced both Government responses to the industry's problems and dairymen's decisions about levels of production and farm viability. Examination of the spatial impact on the now declining Australian dairy industry of Government-funded subsidies and of schemes for reconstruction of non-viable dairy farms, has indicated that withdrawal of farmers from the industry has not been areally uniform at the national level; but study of a major dairying region whose industry has undergone substantial decline suggests that this uneven pattern reflects industry and regional characteristics more than the deliberate or inadvertent results of Government intervention. Although Government policy has been broadly directed towards reducing the numbers of dairymen, and hence dependence on overseas prices for production surpluses, industry change has been greatest in regions where viable economic alternatives have been available for low-income dairymen. 相似文献
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