Mapping Submerged Aquatic Vegetation with GIS in the Caloosahatchee Estuary: Evaluation of Different Interpolation Methods     

WEIHE GUAN  ROBERT H. CHAMBERLAIN  BRUCE M. SABOL  PETER H. DOERING 《Marine Geodesy》2013,36(2):69-91

This article evaluates different spatial interpolation methods for mapping submerged aquatic vegetation (SAV) in the Caloosahatchee Estuary, Florida. Data used for interpolation were collected by the Submersed Aquatic Vegetation Early Warning System (SAVEWS). The system consists of hydro-acoustic equipment, which operates from a slow-moving boat and records bottom depth, seagrass height, and seagrass density. This information is coupled with geographic location coordinates from a Global Positioning System (GPS) and stored together in digital files, representing SAV status at points along transect lines. Adequate spatial interpolation is needed to present the SAV information, including density, height, and water depth, as spatially continuous data for mapping and for comparison between seasons and years. Interpolation methods examined in this study include ordinary kriging with five different semivariance models combined with a variable number of neighboring points, the inverse distance weighted (IDW) method with different parameters, and the triangulated irregular network (TIN) method with linear and quintic options. Interpolation results were compared with survey data at selected calibration transects to examine the suitability of different interpolation methods. Suitability was quantified by the determination coefficient (R2) and the root-mean-square error (RMSE) between interpolated and observed values. The most suitable interpolation method was identified as the one yielding the highest R2 value and/or the lowest RMSE value. For different geographic conditions, seasons, and SAV parameters, different interpolation methods were recommended. This study identified that kriging was more suitable than the IDW or TIN method for spatial interpolation of all SAV parameters measured. It also suggested that transect data with irregular spatial distribution patterns such as SAV parameters are sensitive to interpolation methods. An inappropriate interpolation method such as TIN can lead to erroneous spatial representation of the SAV status. With a functional geographic system and adequate computing power, the evaluation and selection of interpolation methods can be automated and quantitative, leading to a more efficient and accurate decision.  相似文献   

Evidence for carbonate platform failure during rapid sea‐level rise; ca 14 000 year old bioclastic flow deposits in the Lesser Antilles     

JESSICA TROFIMOVS  JODIE K. FISHER  HEATHER A. MACDONALD  PETER J. TALLING  R. STEPHEN J. SPARKS  MALCOLM B. HART  CHRISTOPHER W. SMART  GEORGES BOUDON  CHRISTINE DEPLUS  JEAN‐CHRISTOPHE KOMOROWSKI  ANNE LE FRIANT  STEVEN G. MORETON  MELANIE J. LENG 《Sedimentology》2010,57(3):735-759

Bioclastic flow deposits offshore from the Soufrière Hills volcano on Montserrat in the Lesser Antilles were deposited by the largest volume sediment flows near this active volcano in the last 26 kyr. The volume of these deposits exceeds that of the largest historic volcanic dome collapse in the world, which occurred on Montserrat in 2003. These flows were most probably generated by a large submarine slope failure of the carbonate shelf comprising the south‐west flank of Antigua or the east flank of Redonda; adjacent islands that are not volcanically active. The bioclastic flow deposits are relatively coarse‐grained and either ungraded or poorly graded, and were deposited by non‐cohesive debris flow and high density turbidity currents. The bioclastic deposit often comprises multiple sub‐units that cannot be correlated between core sites; some located just 2 km apart. Multiple sub‐units in the bioclastic deposit result from either flow reflection, stacking of multiple debris flow lobes, and/or multi‐stage collapse of the initial landslide. This study provides unusually precise constraints on the age of this mass flow event that occurred at ca 14 ka. Few large submarine landslides have been well dated, but the slope failures that have been dated are commonly associated with periods of rapid sea‐level change.  相似文献   

A direct way of specifying flow-dependent background error correlations for meteorological analysis systems   总被引：1，自引：0，他引：1  

LARS PETER RIISHØJGAARD 《地球，A辑:动力气象学与海洋学》1998,50(1):42-57

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EFFECTS OF CLIMATE CHANGE ON FRESHWATER ECOSYSTEMS OF THE SOUTH-EASTERN UNITED STATES AND THE GULF COAST OF MEXICO     

PATRICK J. MULHOLLAND  G. RONNIE BEST  CHARLES C. COUTANT  GEORGE M. HORNBERGER  JUDY L. MEYER  PETER J. ROBINSON  JOHN R. STENBERG  R. EUGENE TURNER  FRANCISCO VERA-HERRERA  ROBERT G. WETZEL 《水文研究》1997,11(8):949-970

The south-eastern United States and Gulf Coast of Mexico is physiographically diverse, although dominated by a broad coastal plain. Much of the region has a humid, warm temperate climate with little seasonality in precipitation but strong seasonality in runoff owing to high rates of summer evapotranspiration. The climate of southern Florida and eastern Mexico is subtropical with a distinct summer wet season and winter dry season. Regional climate models suggest that climate change resulting from a doubling of the pre-industrial levels of atmospheric CO₂ may increase annual air temperatures by 3–4°C. Changes in precipitation are highly uncertain, but the most probable scenario shows higher levels over all but the northern, interior portions of the region, with increases primarily occurring in summer and occurring as more intense or clustered storms. Despite the increases in precipitation, runoff is likely to decline over much of the region owing to increases in evapotranspiration exceeding increases in precipitation. Only in Florida and the Gulf Coast areas of the US and Mexico are precipitation increases likely to exceed evapotranspiration increases, producing an increase in runoff. However, increases in storm intensity and clustering are likely to result in more extreme hydrographs, with larger peaks in flow but lower baseflows and longer periods of drought. The ecological effects of climate change on freshwaters of the region include: (1) a general increase in rates of primary production, organic matter decomposition and nutrient cycling as a result of higher temperatures and longer growing seasons: (2) reduction in habitat for cool water species, particularly fish and macroinvertebrates in Appalachian streams; (3) reduction in water quality and in suitable habitat in summer owing to lower baseflows and intensification of the temperature–dissolved oxygen squeeze in many rivers and reservoirs; (4) reduction in organic matter storage and loss of organisms during more intense flushing events in some streams and wetlands; (5) shorter periods of inundation of riparian wetlands and greater drying of wetland soils, particularly in northern and inland areas; (6) expansion of subtropical species northwards, including several non-native nuisance species currently confined to southern Florida; (7) expansion of wetlands in Florida and coastal Mexico, but increase in eutrophication of Florida lakes as a result of greater runoff from urban and agricultural areas; and (8) changes in the flushing rate of estuaries that would alter their salinity regimes, stratification and water quality as well as influence productivity in the Gulf of Mexico. Many of the expected climate change effects will exacerbate current anthropogenic stresses on the region's freshwater systems, including increasing demands for water, increasing waste heat loadings and land use changes that alter the quantity and quality of runoff to streams and reservoirs. Research is needed especially in several critical areas: long-term monitoring of key hydrological, chemical and biological properties (particularly water balances in small, forested catchments and temperature-sensitive species); experimental studies of the effects of warming on organisms and ecosystem processes under realistic conditions (e.g. in situ heating experiments); studies of the effects of natural hydrological variation on biological communities; and assessment of the effects of water management activities on organisms and ecosystem processes, including development and testing of management and restoration strategies designed to counteract changes in climate. © 1997 John Wiley & Sons, Ltd.  相似文献   

Variations in the discharge and organic matter content of stalagmite drip waters in Lower Cave,Bristol     

ANDY BAKER  WILLIAM L. BARNES  PETER L. SMART 《水文研究》1997,11(11):1541-1555

Six drip waters, which were actively depositing stalagmites in Lower Cave, Bristol, were analysed both for discharge and luminescence properties. Drip discharges were determined for two different years, and show a complex response to surface precipitation variations. Inter annual variability in drip discharge is demonstrated to be significantly higher than intra-annual variability, and discharge was demonstrated both to increase and decrease non-linearly with increased precipitation. Drip waters demonstrate a correlation between their luminescence intensity and drip discharge, with increased luminescence in winter as more organic matter is flushed through the aquifer. The strength of the relationship between luminescence intensity and discharge increases with increased discharge. The results presented here have implications for the palaeoenvironmental interpretation of annual growth laminae and the growth rates of stalagmite samples. © 1997 John Wiley & Sons, Ltd.  相似文献   

Book Review: SOILS AND ENVIRONMENT by S. Ellis and A. Mellor. Routledge, 1995. 364 pp. £55.00 ($82.50) (hbk), £16.99 ($25.50) (pbk). ISBN 0 415 06887 8 (hbk); 415 06888 8 (pbk)     

PETER JAMES 《Geological Journal》1997,32(2):194-194

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A Late Quaternary catastrophic flood in the Lahul Himalayas     

PETER COXON  LEWIS A. OWEN  WISHART A. MITCHELL 《第四纪科学杂志》1996,11(6):495-510

Impressive flood deposits are described resulting from a catastrophic lake outburst in the Upper Chandra valley in the Lahul Himalaya, northern India. Reconstructions of the former glacial lake, Glacial Lake Batal, and the discharges were undertaken using landforms and sediment data. The glacial dam burst released 1.496 km³ of water in 0.72 days, with peak discharges of between 21000 and 27000 m³ s⁻¹ at Batal. Dating by OSL suggests the flood occurred ca. 36.9 ± 8.4 to 43.4 ± 10.3 ka ago. This cataclysmic flood was responsible for major resedimentation and landscape modification within the Chandra valley.  相似文献   

AN INTEGRATED APPROACH TO MODELLING HYDROLOGY AND WATER QUALITY IN GLACIERIZED CATCHMENTS     

KEITH RICHARDS  MARTIN SHARP  NEIL ARNOLD  ANGELA GURNELL  MICHAEL CLARK  MARTIN TRANTER  PETER NIENOW  GILES BROWN  IAN WILLIS  WENDY LAWSON 《水文研究》1996,10(4):479-508

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