Assessing regional‐scale spatio‐temporal patterns of groundwater–surface water interactions using a coupled SWAT‐MODFLOW model          下载免费PDF全文

Ryan T. Bailey  Tyler C. Wible  Mazdak Arabi  Rosemary M. Records  Jeffrey Ditty 《水文研究》2016,30(23):4420-4433

Interaction between groundwater and surface water in watersheds has significant impacts on water management and water rights, nutrient loading from aquifers to streams, and in‐stream flow requirements for aquatic species. Of particular importance are the spatial patterns of these interactions. This study explores the spatio‐temporal patterns of groundwater discharge to a river system in a semi‐arid region, with methods applied to the Sprague River Watershed (4100 km²) within the Upper Klamath Basin in Oregon, USA. Patterns of groundwater–surface water interaction are explored throughout the watershed during the 1970–2003 time period using a coupled SWAT‐MODFLOW model tested against streamflow, groundwater level and field‐estimated reach‐specific groundwater discharge rates. Daily time steps and coupling are used, with groundwater discharge rates calculated for each model computational point along the stream. Model results also are averaged by month and by year to determine seasonal and decadal trends in groundwater discharge rates. Results show high spatial variability in groundwater discharge, with several locations showing no groundwater/surface water interaction. Average annual groundwater discharge is 20.5 m³/s, with maximum and minimum rates occurring in September–October and March–April, respectively. Annual average rates increase by approximately 0.02 m³/s per year over the 34‐year period, negligible compared with the average annual rate, although 70% of the stream network experiences an increase in groundwater discharge rate between 1970 and 2003. Results can assist with water management, identifying potential locations of heavy nutrient mass loading from the aquifer to streams and ecological assessment and planning focused on locations of high groundwater discharge. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Devon's desert ‘worms’     

Robert A. Coram  Jonathan D. Radley 《Geology Today》2016,32(2):65-69

Worm‐like trace fossils, sometimes of large size, have regularly been reported from the otherwise generally poorly‐fossiliferous Permo‐Triassic continental red beds of the East Devon coast, southwest England. Selected examples are discussed here to outline the difficulties involved in elucidating the true producers of these burrows and interpreting their significance in the local palaeoenvironment.  相似文献   

Characterizing and classifying urban watersheds with compositional and structural attributes     

Joseph M. Delesantro  Jonathan M. Duncan  Diego Riveros-Iregui  Joanna R. Blaszczak  Emily S. Bernhardt  Dean L. Urban  Lawrence E. Band 《水文研究》2021,35(9):e14339

Current land-use classifications used to assess urbanization effects on stream water quality date back to the 1980s when limited information was available to characterize watershed attributes that mediate non-point source pollution. With high resolution remote sensing and widely used GIS tools, there has been a vast increase in the availability and precision of geospatial data of built environments. In this study, we leverage geospatial data to expand the characterization of developed landscapes and create a typology that allows us to better understand the impact of complex developed landscapes across the rural to urban gradient. We assess the ability of the developed landscape typology to reveal patterns in stream water chemistry previously undetected by traditional land-cover based classification. We examine the distribution of land-cover, infrastructure, topography and geology across 3876 National Hydrography Dataset Plus catchments in the Piedmont region of North Carolina, USA. From this dataset, we generate metrics to evaluate the abundance, density and position of landscape features relative to streams, catchment outlets and topographic wetness metrics. While impervious surfaces are a key distinguishing feature of the urban landscape, sanitary infrastructure, population density and geology are better predictors of baseflow stream water chemistry. Unsupervised clustering was used to generate a distinct developed landscape typology based on the expanded, high-resolution landscape feature information. Using stream chemistry data from 37 developed headwater catchments, we compared the baseflow water chemistry grouped by traditional land-cover based classes of urbanization (rural, low, medium and high density) to our composition and structure-based classification (a nine-class typology). The typology based on 22 metrics of developed landscape composition and structure explained over 50% of the variation in NO₃⁻-N, TDN, DOC, Cl⁻, and Br⁻ concentration, while the ISC-based classification only significantly explained 23% of the variation in TDN. These results demonstrate the importance of infrastructure, population and geology in defining developed landscapes and improving discrete classes for water management.  相似文献   

Uncertainty analysis of a model of wind-blown volcanic plumes     

Mark J. Woodhouse  Andrew J. Hogg  Jeremy C. Phillips  Jonathan C. Rougier 《Bulletin of Volcanology》2015,77(10):1-28

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Intensification of Southern Hemisphere westerly winds 2000–1000 years ago: evidence from the subantarctic Campbell and Auckland Islands (52–50°S)          下载免费PDF全文

Chris S. M. Turney  Matt McGlone  Jonathan Palmer  Christopher Fogwill  Alan Hogg  Zoë A. Thomas  Mathew Lipson  Janet M. Wilmshurst  Pavla Fenwick  Richard T. Jones  Ben Hines  Graeme F. Clark 《第四纪科学杂志》2016,31(1):12-19

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Incorporating climate change and morphological uncertainty into coastal change hazard assessments     

Heather M. Baron  Peter Ruggiero  Nathan J. Wood  Erica L. Harris  Jonathan Allan  Paul D. Komar  Patrick Corcoran 《Natural Hazards》2015,75(3):2081-2102

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Evaluation of regional ocean circulation models for the Mediterranean Sea at the Strait of Gibraltar: volume transport and thermohaline properties of the outflow     

Javier Soto-Navarro  Samuel Somot  Florence Sevault  Jonathan Beuvier  Francisco Criado-Aldeanueva  Jesús García-Lafuente  Karine Béranger 《Climate Dynamics》2015,44(5-6):1277-1292

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English Jurassic Limestone Country: Stroud,Central Cotswolds          下载免费PDF全文

Jonathan Paul 《Geology Today》2015,31(1):28-32

The area around Stroud, a small English market town perched on the steep west‐facing Cotswold escarpment, offers some of the most dramatic outcrops of Jurassic limestone in the UK. From sweeping vistas of the Severn Vale, to the deeply wooded river valleys that indent the escarpment, its landscape is undeniably one of the area's greatest assets. Recently, the geology and physiography of the landscape has been drawn into close focus by several notable UK media stories: protests against hydraulic fracturing (fracking) in the underlying Lias clays; landslides causing weeks of repeated disruption across the Cotswold road and railway networks; and the recent death of a local engineer in a pit collapse of Fuller's Earth. In order to understand these stories in greater depth, it is useful to consider the story of Stroud's unique physical setting.  相似文献   

Geoarchaeological Investigations in Mesoamerica Move into the 21st Century: A Review     

Nicholas P. Dunning  Carmen McCane  Tyler Swinney  Matthew Purtill  Jani Sparks  Ashley Mann  Jon‐Paul McCool  Chantal Ivenso 《Geoarchaeology》2015,30(3):167-199

Over the past thirty years, geoarchaeology has moved from the fringe to mainstream status within Mesoamerican archaeological investigations. This review focuses on works published since the year 2000. Five themes are identified as central to recent studies: (1) the correlation of environmental change and cultural history; (2) anthropogenic environmental impacts; (3) ancient land cover, land use, and diet; (4) archaeological prospection; and (5) provenance studies. These themes are often interwoven in the application of complex systems approaches that allow scientists to more accurately model the intricacies of ancient human–environment interactions.  相似文献   

A diatom‐inferred record of lake variability during the last 900 years in Lützow–Holm Bay,East Antarctica          下载免费PDF全文

Rachel C. Rudd  Jonathan J. Tyler  John Tibby  Yusuke Yokoyama  Ines Tavernier  Elie Verleyen  Manabu Fukui  Yoshinori Takano 《第四纪科学杂志》2016,31(2):114-125

Decadal–centennial‐scale climate variability in coastal Antarctica remains poorly understood due to the limited number of highly resolved, well‐dated records. We present a 900‐year, decadal‐scale reconstruction based on sedimentary diatoms from Lake Abi in Lützow–Holm Bay, East Antarctica. Hydrological change is inferred from diatom ecological preferences in conjunction with an existing regional training set and implies that lake water specific conductivity, depth and nitrogen availability are the key drivers of diatom assemblage change. Lake Abi underwent a series of subtle environmental changes related to these environmental variables, possibly driven by changes in catchment snow melt and the duration of seasonal ice cover. Ordination is used to trace the major patterns of change in the diatom community, with notable shifts identified between 470 and 400 and at ～350 cal a BP (where present = CE 1950). The frequency of environmental variability at Lake Abi is broadly consistent with a record of the Interdecadal Pacific Oscillation during the last millennium, but contrasts with the apparent climate stability elsewhere in eastern Antarctica. Further research is required to constrain the limnological and ecological responses of lakes in coastal Antarctica to obtain more rigorous palaeoclimate reconstructions from these sites of immense potential.  相似文献