Calculation of lava effusion rates from Landsat TM data   总被引：1，自引：0，他引：1  

Andrew J. L. Harris  Luke P. Flynn  Laszlo Keszthelyi  Peter J. Mouginis-Mark  Scott K. Rowland  Joseph A. Resing 《Bulletin of Volcanology》1998,60(1):52-71

 We present a thermal model to calculate the total thermal flux for lava flowing in tubes, on the surface, or under shallow water. Once defined, we use the total thermal flux to estimate effusion rates for active flows at Kilauea, Hawaii, on two dates. Input parameters were derived from Landsat Thematic Mapper (TM), field and laboratory measurements. Using these parameters we obtain effusion rates of 1.76±0.57 and 0.78±0.27 m³ s^–1 on 23 July and 11 October 1991, respectively. These rates are corroborated by field measurements of 1.36±0.14 and 0.89±0.09 m³s^–1 for the same dates (Kauahikaua et al. 1996). Using weather satellite (AVHRR) data of lower spatial resolution, we obtain similar effusion rates for an additional 26 dates between the two TM-derived measurements. We assume that, although total effusion rates at the source declined over the period, the shut down of the ocean entry meant that effusion rates for the surface flows alone remained stable. Such synergetic use of remotely sensed data provides measurements that can (a) contribute to monitoring flow-field evolution, and (b) provide reliable numerical data for input into rheological and thermal models. We look forward to being able to produce estimates for effusion rates using data from high-spatial-resolution sensors in the earth observing system (EOS) era, such as Landsat 7, the hyperspectral imager, the advanced spaceborne thermal emission spectrometer, and the advanced land imager. Received: 25 July 1997 / Accepted: 26 February 1998  相似文献   

Declining towns in the former USSR     

Rowland RH 《Post-Soviet geography》1994,35(6):352-365

"The paper comprises an update of an earlier study...focused on towns with declining population during the 1959-1970 period. Based on recently published data on individual urban centers with 15,000 or more inhabitants reported in the 1979 and 1989 censuses, it identifies centers where population declined from 1970 to 1989. The study also assesses selected geographical aspects, economic functions, and size characteristics of such urban centers. Comparisons with data from the 1959-1970 period are made to arrive at a 30-year perspective."  相似文献   

Internal Migration Between Statistical Areas of New Zealand 1966–1971     

D. T. Rowland 《New Zealand geographer》1976,32(2):160-176

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Regional migration and ethnic Russian population change in the USSR (1959-79)     

Rowland RH 《Soviet geography》1982,23(8):557-583

"The related topics of regional net migration and ethnic Russian population redistribution and change in the USSR are investigated for the intercensal period 1970-79 in comparison to 1959-70 by economic regions and subdivisions. The results reveal that the main migration and Russian shifts continued to be from internal to peripheral regions. However, compared with the 1959-70 period, regional rates for 1970-79 were more equalized, and a south-to-north shift seemed to be occurring in both cases." The author notes that "aggregate measures...suggest that the traditional eastward movement of Russians is slowing. Correlation analysis indicates that migration and ethnic Russian change patterns are associated with selected indices of modernization. The south-to-north shift, in particular, has been fairly strong in relation to changes in capital investment. Prospects of a northward migration of Turkic Moslems from Central Asia are also discussed."  相似文献   

Superposed deformation in turbidites and syn-sedimentary slides of the tectonically active Miocene Waitemata Basin, northern New Zealand     

K. B. Spörli  J. V. Rowland 《Basin Research》2007,19(2):199-216

The Miocene Waitemata Basin was deposited on a moving base provided by the Northland Allochthon, which was emplaced in the Late Oligocene, as a new convergent plate boundary was established in northern New Zealand. The basin experienced complex interaction between tectonic and gravity‐driven shallow deformation. Spectacular examples of the resulting structures exposed on eastern Whangaparaoa Peninsula 50 km north of Auckland provide a world‐class example of weak rock deformation, the neglected domain between soft‐sediment and hard rock deformation. Quartz‐poor turbidite sequences display a protracted sequence of deformations: D1, synsedimentary slumping; D2, large scale deeper‐seated sliding and extensional low‐angle shearing, associated with generation of boudinage and broken formation; D3, thrusting and folding, indicating transport mostly to the SE; D4, thrusting and folding in the opposite direction; D5, further folding, including sinistral shear; D6, steep faults. The deformation sequence suggests continuous or intermittent southeastward transport of units with increasing sedimentary and structural burial. By phase D3, the rocks had passed from the soft‐sediment state to low levels of consolidation. However, with a compressive strength of ～5 MPa they are weak rocks even today. Such weak‐rock deformation must be important in other sedimentary basins, especially those associated with active convergent plate boundaries and with immature source areas for their sediments.  相似文献   

Lengths and hazards from channel-fed lava flows on Mauna Loa, Hawai‘i, determined from thermal and downslope modeling with FLOWGO     

Scott K. Rowland  Harold Garbeil  Andrew J. L. Harris 《Bulletin of Volcanology》2005,67(7):634-647

Using the FLOWGO thermo-rheological model we have determined cooling-limited lengths of channel-fed (i.e. a) lava flows from Mauna Loa. We set up the program to run autonomously, starting lava flows from every 4th line and sample in a 30-m spatial-resolution SRTM DEM within regions corresponding to the NE and SW rift zones and the N flank of the volcano. We consider that each model run represents an effective effusion rate, which for an actual flow coincides with it reaching 90% of its total length. We ran the model at effective effusion rates ranging from 1 to 1,000 m³ s^–1, and determined the cooling-limited channel length for each. Keeping in mind that most flows extend 1–2 km beyond the end of their well-developed channels and that our results are non-probabilistic in that they give all potential vent sites an equal likelihood to erupt, lava coverage results include the following: SW rift zone flows threaten almost all of Mauna Loas SW flanks, even at effective effusion rates as low as 50 m³ s^–1 (the average effective effusion rate for SW rift zone eruptions since 1843 is close to 400 m³ s^–1). N flank eruptions, although rare in the recent geologic record, have the potential to threaten much of the coastline S of Keauhou with effective effusion rates of 50–100 m³ s^–1, and the coast near Anaehoomalu if effective effusion rates are 400–500 m³ s^–1 (the 1859 a flow reached this coast with an effective effusion rate of 400 m³ s^–1). If the NE rift zone continues to be active only at elevations >2,500 m, in order for a channel-fed flow to reach Hilo the effective effusion rate needs to be 400 m³ s^–1 (the 1984 flow by comparison, had an effective effusion rate of 200 m³ s^–1). Hilo could be threatened by NE rift zone channel-fed flows with lower effective effusion rates but only if they issue from vents at 2,000 m or lower. Populated areas on Mauna Loas SE flanks (e.g. Phala), could be threatened by SW rift zone eruptions with effective effusion rates of 100 m³ s^–1.Editorial responsibility: J Donnelly-Nolan  相似文献   

Changes in the metropolitan and large city populations of the USSR: 1979-85     

Rowland RH 《Soviet geography》1986,27(9):638-658

"This paper investigates the post-census growth of metropolitan areas and large cities in the USSR from 1979 to 1985. The Soviet population continues to be increasingly concentrated in large metropolitan areas and large cities, and although suburbanization occurs within metropolitan areas, a striking feature is that all central cities continue to grow and typically contain the vast majority of the metropolitan population. This reflects the fact that individual large cities continue to loom large, despite policies to limit their growth. Although the growth rates of large cities have slowed, so have those of smaller towns, and a merging of growth rates by size class is occurring."  相似文献   

Professionalization and displacement in Greater London     

Rowland Atkinson 《Area》2000,32(3):287-295

Summary This article presents results from research that has looked at the process of displacement induced by gentrification. The approach uses census data to measure social change to examine the interaction between proxy indicators of gentrification and displacement. Data is presented indicating that links exist between these processes. The paper concludes that while these links do not conclusively demonstrate the existence of displacement it is unlikely that such a strongly observed effect is unrelated to processes of professionalization and that other approaches to the study of displacement are also needed to achieve a more rounded view of the process.  相似文献   

Temporal and spatial pattern of thermokarst lake area changes at Yukon Flats,Alaska          下载免费PDF全文

Min Chen  Joel C. Rowland  Cathy J. Wilson  Garrett L. Altmann  Steven P. Brumby 《水文研究》2014,28(3):837-852

To better understand the linkage between lake area change, permafrost conditions and intra‐annual and inter‐annual variability in climate, we explored the temporal and spatial patterns of lake area changes for a 422 382‐ha study area within Yukon Flats, Alaska using Landsat images of 17 dates between 1984 and 2009. Only closed basin lakes were used in this study. Among the 3529 lakes greater than 1 ha, closed basin lakes accounted for 65% by number and 50% by area. A multiple linear regression model was built to quantify the temporal change in total lake area with consideration of its intra‐annual and inter‐annual variability. The results showed that 80.7% of lake area variability was attributed to intra‐annual and inter‐annual variability in local water balance and mean temperature since snowmelt (interpreted as a proxy for seasonal thaw depth). Another 14.3% was associated with long‐term change. Among 2280 lakes, 350 lakes shrank, and 103 lakes expanded. The lakes with similar change trends formed distinct clusters, so did the lakes with similar short term intra‐annual and inter‐annual variability. By analysing potential factors driving lake area changes including evaporation, precipitation, indicators for regional permafrost change, and flooding, we found that ice‐jam flooding events were the most likely explanation for the observed temporal pattern. In addition to changes in the frequency of ice jam flooding events, the observed changes of individual lakes may be influenced by local variability in permafrost distributions and/or degradation. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Three decades of water quality measurements from the Upper Severn experimental catchments at Plynlimon,Wales: an openly accessible data resource for research,modelling, environmental management and education   总被引：1，自引：0，他引：1  

Colin Neal  Brian Reynolds  Dave Norris  James W. Kirchner  Margaret Neal  Phil Rowland  Heather Wickham  Sarah Harman  Linda Armstrong  Darren Sleep  Alan Lawlor  Clive Woods  Bronwen Williams  Matt Fry  Gwen Newton  Dan Wright 《水文研究》2011,25(24):3818-3830

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