Physical Geography最新文献

{"title":"Geomorphology and dynamics of a coastal transgressive dune system, central California","authors":"P. Barrineau, V. P. Tchakerian","doi":"10.1080/02723646.2021.1944462","DOIUrl":"https://doi.org/10.1080/02723646.2021.1944462","url":null,"abstract":"ABSTRACT The Callendar dunes are located within the Santa Maria dune complex in south-central California and have been studied repeatedly since the pioneering work of Bowen and Inman in the 1960's. Previous conceptual models of the system’s Holocene evolution relate variations in dune morphologies to changes in sediment supply and sea level. In the years since their studies, conceptual frameworks of coastal and continental transgressive dune systems provide useful avenues for re-visiting the morphodynamic history of the Callendar dunes. Our study presents grain size and dune spacing data collected by Tchakerian and Mulligan in 1981, while working under Orme as graduate assistants. These data, when considered in light of the more recent conceptual frameworks mentioned above, suggest that the Callendar dunes may exhibit some elements of self-organization. With this in mind, we apply a conceptual model of coastal transgressive dune systems to help elucidate some of the historical morphodynamics influencing the modern arrangement of morphologies at the Callendar dunes.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"122 - 144"},"PeriodicalIF":1.6,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1944462","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47933581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climatic implications of late Holocene loess and intervening paleosols, Southern Zanskar range, northwestern Himalaya","authors":"A. Lone, Shubhra Sharma, H. Achyuthan, A. Shukla, R. Shah, S. Sangode, F. A. A.","doi":"10.1080/02723646.2021.1938501","DOIUrl":"https://doi.org/10.1080/02723646.2021.1938501","url":null,"abstract":"ABSTRACT The loess-paleosol proxy records from mid-latitude Asia have been instrumental in the reconstruction of regional paleoclimate evolution and its relationship with global climatic changes. The present study explores the discrete occurrence of a loess and paleosol sequence (LPS) in the Southern Zanskar Range (SZR), NW Himalaya. Stratigraphic variations in sediment texture, supplemented with geochemical, organic and magnetic proxies, indicate two broad phases of loess accretion (L-1) and paleosol formation (PS-1). The older phase of loess accretion (L-1) is dated between 2.5 ± 0.3 ka and >2.0 ka, whereas the L-2, which fully transformed into the modern soil (MS) probably deposited during the Little Ice Age (LIA) phase. The textural attributes (high sand content) of loess indicate source proximal deposition, whereas the geochemical and magnetic proxies point towards the pre-depositional weathering (in the source area). The PS-1 dated to 2189 ± 296 cal yr BP indicates improved moisture conditions, whereas the MS is assigned to post LIA warm phase. These findings provide an important step towards better understanding the sensitivity of loess accretion and paleosol formation in the SZR linked to late Holocene climate variability.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"44 1","pages":"287 - 306"},"PeriodicalIF":1.6,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1938501","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44146356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution and management of Atlantic Canadian coastal dunes over the next century","authors":"J. Ollerhead, R. Davidson-Arnott","doi":"10.1080/02723646.2021.1936790","DOIUrl":"https://doi.org/10.1080/02723646.2021.1936790","url":null,"abstract":"ABSTRACT Dune systems in Atlantic Canada are relatively small given a relatively low sediment supply. The dunes are built primarily of reworked sediments as relative sea level (RSL) has risen. The foredune (at least) is reworked several times a decade by extreme weather events and many are transgressing on a decadal scale as a result of normal geomorphic processes. The key drivers shaping the dunes are, however, changing over time with climate change.The rate of RSL rise is accelerating, which will almost certainly mean an acceleration of dune transgression rates. As well, there is some evidence that storms are becoming more frequent and sea ice is diminishing, meaning more frequent reactivation. Predicting how dunes will respond to changes in the key controlling variables on an annual or decadal scale is challenging. Examination of how the dunes evolve on a decadal to century scale, however, suggests that the dunes in Atlantic Canada should continue to exist. Thus, we advocate using a dune management approach that focuses on minimizing human impacts and allowing natural processes to continue unimpeded. The highest priority for managing our coastal dunes should be to provide them with sufficient accommodation space into which they can transgress naturally.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"98 - 121"},"PeriodicalIF":1.6,"publicationDate":"2021-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1936790","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45440917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling seasonal sediment yields for a medium-scale temperate forest/agricultural watershed","authors":"C. Day, J. Liebman","doi":"10.1080/02723646.2021.1934957","DOIUrl":"https://doi.org/10.1080/02723646.2021.1934957","url":null,"abstract":"ABSTRACT As vegetation cover senesces across temperate watersheds, the potential for soil erosion and subsequent sediment yields increases. Despite the importance of vegetation dynamics and evapotranspiration towards influencing watershed-scale hydrological processes, limited research has fully included these variables in modeling sediment yields, relying on surface runoff records alone. Focusing on the Upper Floyds Fork watershed, Kentucky, we applied a multi-objective approach utilizing MODIS-derived estimations of vegetation and evapotranspiration (ET) to calibrate the Soil and Water Assessment Tool (SWAT) towards modeling seasonal sediment yields May 2019-April 2020. Results generated satisfactory error measures across all four variables (vegetation cover, ET, runoff, sediment). Above average precipitation and elevated erosive storm activity generated significant sediment yields even during months of greater vegetation coverage. Conversely, below average precipitation during Aug–Sep resulted in minimal sediment yields despite diminishing vegetation coverage. While precipitation acted as the dominant process controlling sediment yields, higher yields were also predicted in sub-watersheds as a function of steeper slopes, higher soil erodibilities and increased agricultural land cover during the dormant winter period. These findings may help identify when to expect increased sediment loads towards targeting specific sub-watersheds in managing future soil erosion, and defining and establishing best management practices in the future.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"829 - 852"},"PeriodicalIF":1.6,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1934957","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49534091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal variability and trends of drought episode in southeastern Ethiopia","authors":"Mekonnen Adnew Degefu, Yonas T. Tadesse, W. Bewket","doi":"10.1080/02723646.2021.1930654","DOIUrl":"https://doi.org/10.1080/02723646.2021.1930654","url":null,"abstract":"ABSTRACT There is a need for scientific knowledge on the spatiotemporal variability of drought episodes to establish robust drought mitigation and adaptation strategies. This study evaluates the spatiotemporal variability of drought episodes in southeastern Ethiopia at multiple time scales (3-, 6-, 12- and 24-month and three spatially different wet seasons; March–May, June–September and September–November). Drought indices were generated for 34 stations using the standardized precipitation index (SPI). The results show that the frequency and magnitude of drought episodes do not have a clear spatial pattern among nearby stations. The 12- and 24-month SPI confirm that there has not been a year without drought (SPI≤ −1) between 1970 and 2015 at some stations in the study area. The trend tests show that drought magnitude, duration and geographical coverage are increasing. The increasing trends in drought magnitude at the annual, 24-month and during the March–May season were statistically significant at 0.05 level. Drought duration at 3-month time scale also showed a statistically significant increase. The results of this study provide relevant drought information at multiple time scales that is useful for supporting drought management in the southeastern Ethiopia.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"534 - 561"},"PeriodicalIF":1.6,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1930654","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47217881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short communication: evidence for geologic control of rip channels along Prince Edward Island, Canada","authors":"P. Wernette, C. Houser","doi":"10.1080/02723646.2021.1923389","DOIUrl":"https://doi.org/10.1080/02723646.2021.1923389","url":null,"abstract":"ABSTRACT Rip currents can move unsuspecting swimmers offshore rapidly and represent a significant risk to beach users worldwide, including along the northern coast of Prince Edward Island (PEI), Canada. Although many rip currents are ephemeral and/or spatially variable in response to changes in the nearshore bar morphology and wave and tidal forcing, it is possible for rip channels to be geologically controlled and quasi-permanent in morphology, location, and flow. Several rip channels along the northern coast of PEI appear in the same location from year to year and correspond to elongated lakes, rivers, or swales behind the modern coastal dune system. Given their persistent location and alignment with back dune hydrology, ground-penetrating radar surveys were collected along Brackley and Cavendish Beaches in July 2019 to determine whether persistent rip channels are associated with now-buried river channels extending beneath the modern dunes and continuing offshore. Strong reflectors similar to V-shaped river valleys are present in alongshore transects at both beaches. These infilled valleys align with back-dune hydrology and persistent rip channels, suggesting modern rip channels are structurally controlled and maintained by antecedent geology. This link provides important guidance to beach access management and the distribution of lifesaving strategies along the affected beaches.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"145 - 162"},"PeriodicalIF":1.6,"publicationDate":"2021-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1923389","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46612955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated neural network identification of cirques","authors":"L. Scuderi, T. Nagle-McNaughton","doi":"10.1080/02723646.2021.1928871","DOIUrl":"https://doi.org/10.1080/02723646.2021.1928871","url":null,"abstract":"ABSTRACT Morphological characteristics of cirques have been studied for decades; however, no repeatable set of metrics has been derived that can consistently identify them. Perhaps more importantly, there is no consensus definition of the form that distinguishes cirques and clusters of cirques from non-cirques. In our approach, we use Shuttle Radar Topography Mission (SRTM) digital elevation models (DEMs) in a Convolutional Neural Network (CNN) framework to identify cirques in 20 mountain ranges globally. We extracted bounding boxes of cirques in 19 of these study areas and used them to develop a training set for a cirque identification model. The trained model was applied to the Sierra Nevada California to assess whether this algorithmic approach derived from a global dataset could produce consistent results in complex terrain with mutually interacting cirque forms. Using commonalities revealed using this approach, we find that there is a basic, recognizable and morphometrically quantifiable cirque form. This approach can be used to automate the identification of cirque locations and to guide the quantification of cirque form independent of the subjective definitions of individual workers. The approach can also be used to understand cirque form under different environmental conditions, including similar forms on Mars.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"24 - 51"},"PeriodicalIF":1.6,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1928871","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44339965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"It’s an Insect’s World, We Just Live on it: Exploring Entomogeomorphology as a Potential Subdiscipline of Geography","authors":"Kaelin M. Groom","doi":"10.1080/02723646.2021.1928872","DOIUrl":"https://doi.org/10.1080/02723646.2021.1928872","url":null,"abstract":"ABSTRACT There is little doubt insects and other “creepy crawlies” make up the bulk of life on Earth, and yet their immense influence on landscape change and development have not really garnered adequate attention in geomorphologic and zoogeographic research. What studies do exist focus almost exclusively on ants and termites. Unfortunately, this barely scratches the surface of the myriad of ways in which insects influence – and are influenced by – various landscape dynamics. There are so many more “earth movers” within the broad entomologic designation beyond the obvious anthills and burrows, and with them so much potential to discover new and exciting connections between Earth and its most abundant group of occupants. Honoring the chronically curious and exploratory legacy of the late Dr. Orme, this paper offers a review of extant research bridging geomorphology and entomology, supplemented by observational vignettes exploring “entomogeomorphology” as a potential branch of scientific exploration. Much like Dr. Orme’s diverse research foci, there are very few landscapes left untouched by some form of insect activity and it is time we start paying more attention.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"52 - 66"},"PeriodicalIF":1.6,"publicationDate":"2021-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1928872","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44314407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of NLDAS-2 and Downscaled Air Temperature data in Florida","authors":"Jihoon Jung, M. Al-Hamdan, W. Crosson, C. Uejio, C. DuClos, Kristina W. Kintziger, K. Reid, M. Jordan, D. Zierden, J. Spector, T. Insaf","doi":"10.1080/02723646.2021.1928878","DOIUrl":"https://doi.org/10.1080/02723646.2021.1928878","url":null,"abstract":"ABSTRACT A broad spectrum of model-derived weather datasets are available in the US. Because each product integrates atmospheric conditions with different model processes, each produces different statistical biases. This study validated air temperature from NLDAS-2 and a novel statistically downscaled NLDAS-2 against observational weather station data for the state of Florida. We statistically downscaled NLDAS-2 to a 1-km grid product using MODIS land surface temperature. We investigated mean biases and Pearson correlation coefficients between daily observational data and the two model-derived datasets. We then calculated multiple Climate Extremes Indices to further scrutinize differences in capturing extreme temperatures. Finally, we quantified potential causes of systematic NLDAS-2 biases related to distance from the coast, urban heat island, land cover, and type of observational stations. Two model-derived datasets showed similar mean biases and correspondence with observational data, underestimating maximum temperature by 1°C and overestimating minimum temperature by 2°C. Extreme temperatures were well simulated in both datasets. However, we still found overestimated extreme minimum temperatures and underestimated extreme maximum temperatures. Systematic biases tended to be higher for coastal stations and grids having a high fraction of water. Our study suggests that including physical processes covering land surface and ocean interactions may improve the model accuracy.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"562 - 588"},"PeriodicalIF":1.6,"publicationDate":"2021-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1928878","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45588086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coastal relict landforms and the legacy of Tony Orme","authors":"Casey D. Allen, T. Paradise","doi":"10.1080/02723646.2021.1919380","DOIUrl":"https://doi.org/10.1080/02723646.2021.1919380","url":null,"abstract":"While perhaps best be known by outsiders as a coastal geomorphology expert, Dr. Antony Orme was in fact a consummate example of a well-rounded field geomorphologist, as evinced by his wide-ranging publications which focused on topics from tectonism, beaches, and paleoecology to geomorphology history (of the discipline), Pleistocene research, and climatic geomorphology, among others. This field tradition was passed onto many of his students who, in turn, continue to pass on such traditions to their students. While we were fortunate to have many strong mentors along our paths, the encouragement and continued camaraderie by our PhD Advisor (Ron Dorn) nonetheless, and at least partially, stemmed from his advisor, Dr. Antony “Tony” Orme. Without Tony’s own desire to explore the world and nature – and coasts specifically – perhaps we (the authors) would not have had successes in our own field-based research endeavors (Allen, 2005, 2012, 2017, 2019; Dorn et al., 2013; Paradise, 2012, 1995, 2005, 2010). Although we both retain strong inclinations for empirical research and fieldwork, having enjoyed exploring since we were young, without proper guidance, that spirit can easily become extinguished. Had Tony not passed on his love of exploration and adventure to his students, maybe our advisor would not have done so either, leaving many landscapes and landforms undiscovered and unexplained. We feel fortunate to have benefited from his legacy that has allowed us to conduct geomorphic fieldwork in very interesting locations, on very intriguing landforms, and across landscapes at local, regional, and international scales. As we both continue to explore and guide our own academic children (and grandchildren) just as he did, we continue to perpetuate the legacy and indomitable nature of a great geographer and geomorphologist, Dr. Antony Orme. It is with this spirit of Tony’s intrepidness, we present this article examining two types of relict landforms, selected regionally due to our current respective locales, that highlight some of our recently undertaken field-based research in the US and Caribbean we believe would have intrigued our academic grandfather.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"1 - 23"},"PeriodicalIF":1.6,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1919380","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43241771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}