Pub Date : 2021-09-14DOI: 10.1080/02723646.2021.1966981
B. Abad, B. Salahi, K. Raispour, M. de Luis, R. Serrano, M. Moradi
ABSTRACT Land surface temperature (LST) is an atmosphere-land interaction, which represents the first thermal reaction of the environmental changes occurring in the earth surface, being one of the most important factors used in the earth sciences. Jazmourian basin, in the southeast of Iran, is a fertile agricultural land with diverse topography and unique climatic conditions. Due to its significance as one of the most important agricultural poles of Iran, the LST variations are of great interest due to their high impact on the environmental processes, especially in the land cover. In recent years, Moderate Resolution Imaging Spectroradiometer images have been extensively used to estimate the LST due to their spatial and temporal homogeneity and freely available showing improved capabilities of climate analysis in the areas with scarce observation networks. We used a combination of MOD11C3 and MYD11C3 products of daytime and nighttime LST, covering the complete circadian cycle over Jazmourian basin, from 2003 to 2019. Results showed varied trends by months with a significantly positive increase in January. The spatial distribution revealed a generalized positive anomaly in the whole study area, with the highest values in central lowlands and lowest at eastern high elevations of the basin. The temporal and spatial analyses indicated high temperature differences between months and seasons as well as a wide range from −10°C to 65°C.
{"title":"Assessment of LST spatial and temporal changes in Jazmourian basin, southeast Iran","authors":"B. Abad, B. Salahi, K. Raispour, M. de Luis, R. Serrano, M. Moradi","doi":"10.1080/02723646.2021.1966981","DOIUrl":"https://doi.org/10.1080/02723646.2021.1966981","url":null,"abstract":"ABSTRACT Land surface temperature (LST) is an atmosphere-land interaction, which represents the first thermal reaction of the environmental changes occurring in the earth surface, being one of the most important factors used in the earth sciences. Jazmourian basin, in the southeast of Iran, is a fertile agricultural land with diverse topography and unique climatic conditions. Due to its significance as one of the most important agricultural poles of Iran, the LST variations are of great interest due to their high impact on the environmental processes, especially in the land cover. In recent years, Moderate Resolution Imaging Spectroradiometer images have been extensively used to estimate the LST due to their spatial and temporal homogeneity and freely available showing improved capabilities of climate analysis in the areas with scarce observation networks. We used a combination of MOD11C3 and MYD11C3 products of daytime and nighttime LST, covering the complete circadian cycle over Jazmourian basin, from 2003 to 2019. Results showed varied trends by months with a significantly positive increase in January. The spatial distribution revealed a generalized positive anomaly in the whole study area, with the highest values in central lowlands and lowest at eastern high elevations of the basin. The temporal and spatial analyses indicated high temperature differences between months and seasons as well as a wide range from −10°C to 65°C.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43642555","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}
Pub Date : 2021-08-04DOI: 10.1080/02723646.2021.1961361
T. Dindaroglu, V. Tunguz, E. Babur, O. Menshov, M. Battaglia
ABSTRACT Topography is a key factor that affects edaphic, climatic, and biotic factors directly or indirectly. Relationships between Compound Topographic Index (CTI) model and soil properties were investigated in order to determine the ecological potential of the area in order to plan the sustainability of the fertile lands and the rehabilitation of the degraded areas in the study area. Totally 84 soil samples (0–20 cm) collected from different land use types (forest, cropland, rangeland) in Karst Mountain, Andırın-Kahramanmaras, Turkey. The CTI distributions are generated from digital elevation data of 12 m resolution obtained from AlosPalsar Satellite images. Although CTI values changed to Forest> Cropland> Rangeland, the highest correlation was found between CTI and soil moisture content in rangeland (R2 = 0.81). Lower correlations were found with other land uses (R2 = 0.63 in Cropland and R2 = 0.31 in Forest). CEC and Clay content were found to have a significant (p < 0.01) positive correlation with Curvature. Despite a distinctive topographic structure of karst ecosystems, these correlations verified the influence of topography on soil properties. CTI, which has strong correlations with soil moisture content can be used in planning reclamation processes of degraded karst ecosystems.
{"title":"Determination of the relationship among compound Topographic Index (CTI), soil properties and land-use in karst ecosystems","authors":"T. Dindaroglu, V. Tunguz, E. Babur, O. Menshov, M. Battaglia","doi":"10.1080/02723646.2021.1961361","DOIUrl":"https://doi.org/10.1080/02723646.2021.1961361","url":null,"abstract":"ABSTRACT Topography is a key factor that affects edaphic, climatic, and biotic factors directly or indirectly. Relationships between Compound Topographic Index (CTI) model and soil properties were investigated in order to determine the ecological potential of the area in order to plan the sustainability of the fertile lands and the rehabilitation of the degraded areas in the study area. Totally 84 soil samples (0–20 cm) collected from different land use types (forest, cropland, rangeland) in Karst Mountain, Andırın-Kahramanmaras, Turkey. The CTI distributions are generated from digital elevation data of 12 m resolution obtained from AlosPalsar Satellite images. Although CTI values changed to Forest> Cropland> Rangeland, the highest correlation was found between CTI and soil moisture content in rangeland (R2 = 0.81). Lower correlations were found with other land uses (R2 = 0.63 in Cropland and R2 = 0.31 in Forest). CEC and Clay content were found to have a significant (p < 0.01) positive correlation with Curvature. Despite a distinctive topographic structure of karst ecosystems, these correlations verified the influence of topography on soil properties. CTI, which has strong correlations with soil moisture content can be used in planning reclamation processes of degraded karst ecosystems.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1961361","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48241326","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}
Pub Date : 2021-07-29DOI: 10.1080/02723646.2021.1934964
Christian González, M. Kelley, M. Marvin, Norma López-Castañeda, R. Dorn, M. Schmeeckle
ABSTRACT Ephemeral channels incise into the piedmonts (both alluvial fans and pediments) of the northeastern Sonoran Desert, USA. Located around metropolitan Phoenix, this tectonically quiescent region experienced only aggradation in endorheic structural basins throughout the Pliocene. A wave of aggradation then followed Salt and Gila river integration at the start of the Pleistocene. Aggradation of piedmont base levels continued throughout the rest of the Quaternary. This paper explores two hypotheses to explain piedmont incision despite rising base levels. The classic explanation is that incision is part of the evolution of desert mountain ranges as they decrease in size. A new alternative we propose here involves a lateral shift in base level from Pliocene endorheic basin playas to positions kilometers closer to range fronts in response to river integration. We present a thought exercise of modeling a pediment longitudinal profile as a 1D diffusive system, and we also analyze incision into alluvial fans of the Sierra Estrella range. While our 1D modeling results for pediments are consistent with both explanations for range-front incision, Sierra Estrella bajada incision is best explained by the sudden relocation of the base level to the toe of desert piedmonts.
{"title":"Regional piedmont incision during base-level rise in the northeastern Sonoran Desert, Arizona, USA","authors":"Christian González, M. Kelley, M. Marvin, Norma López-Castañeda, R. Dorn, M. Schmeeckle","doi":"10.1080/02723646.2021.1934964","DOIUrl":"https://doi.org/10.1080/02723646.2021.1934964","url":null,"abstract":"ABSTRACT Ephemeral channels incise into the piedmonts (both alluvial fans and pediments) of the northeastern Sonoran Desert, USA. Located around metropolitan Phoenix, this tectonically quiescent region experienced only aggradation in endorheic structural basins throughout the Pliocene. A wave of aggradation then followed Salt and Gila river integration at the start of the Pleistocene. Aggradation of piedmont base levels continued throughout the rest of the Quaternary. This paper explores two hypotheses to explain piedmont incision despite rising base levels. The classic explanation is that incision is part of the evolution of desert mountain ranges as they decrease in size. A new alternative we propose here involves a lateral shift in base level from Pliocene endorheic basin playas to positions kilometers closer to range fronts in response to river integration. We present a thought exercise of modeling a pediment longitudinal profile as a 1D diffusive system, and we also analyze incision into alluvial fans of the Sierra Estrella range. While our 1D modeling results for pediments are consistent with both explanations for range-front incision, Sierra Estrella bajada incision is best explained by the sudden relocation of the base level to the toe of desert piedmonts.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1934964","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45985184","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}
Pub Date : 2021-07-27DOI: 10.1080/02723646.2021.1943126
Mousaab Zakhrouf, B. Hamid, Sungwon Kim, Stamboul Madani
ABSTRACT Various hybrid approaches combined the different deep learning and machine learning models with evolutionary optimization algorithms and have improved the accuracy of streamflow forecasting problem. In this article, three deep learning models were investigated for streamflow forecasting with various lag times at both stations (i.e. Sidi Aich and Ponteba Defluent), Algeria. Also, a machine learning [i.e. feedforward neural network (FFNN)] model was implemented to compare the forecasting accuracy of deep learning models. The particle swarm optimization algorithm was combined to determine the hyperparameters (i.e. model structure) automatically based on adaptive moment estimation algorithm. The addressed two-stage hybrid models were assessed and evaluated by root mean square error (RMSE), signal-to-noise ratio (SNR), and Nash–Sutcliffe efficiency (NSE) statistical indices. Evaluating all models explained that the GRU II two-stage hybrid model (RMSE = 35.241 m3/s, SNR = 0.5159, and NSE = 0.7337 at Sidi Aich and RMSE = 11.074 m3/s, SNR = 0.3600, and NSE = 0.8703 at Ponteba Defluent) was found to produce more accurate results compared to the Elman recurrent neural network, long short-term memory, and FFNN two-stage hybrid models during testing phase for forecasting streamflow.
{"title":"Novel insights for streamflow forecasting based on deep learning models combined the evolutionary optimization algorithm","authors":"Mousaab Zakhrouf, B. Hamid, Sungwon Kim, Stamboul Madani","doi":"10.1080/02723646.2021.1943126","DOIUrl":"https://doi.org/10.1080/02723646.2021.1943126","url":null,"abstract":"ABSTRACT Various hybrid approaches combined the different deep learning and machine learning models with evolutionary optimization algorithms and have improved the accuracy of streamflow forecasting problem. In this article, three deep learning models were investigated for streamflow forecasting with various lag times at both stations (i.e. Sidi Aich and Ponteba Defluent), Algeria. Also, a machine learning [i.e. feedforward neural network (FFNN)] model was implemented to compare the forecasting accuracy of deep learning models. The particle swarm optimization algorithm was combined to determine the hyperparameters (i.e. model structure) automatically based on adaptive moment estimation algorithm. The addressed two-stage hybrid models were assessed and evaluated by root mean square error (RMSE), signal-to-noise ratio (SNR), and Nash–Sutcliffe efficiency (NSE) statistical indices. Evaluating all models explained that the GRU II two-stage hybrid model (RMSE = 35.241 m3/s, SNR = 0.5159, and NSE = 0.7337 at Sidi Aich and RMSE = 11.074 m3/s, SNR = 0.3600, and NSE = 0.8703 at Ponteba Defluent) was found to produce more accurate results compared to the Elman recurrent neural network, long short-term memory, and FFNN two-stage hybrid models during testing phase for forecasting streamflow.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1943126","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46758114","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}
Pub Date : 2021-07-08DOI: 10.1080/02723646.2021.1938923
Chad W. Hecht, Neil F Laird
ABSTRACT This study investigates the influence of synoptic-scale cold fronts on microclimatic conditions within the complex terrain of Watkins Glen gorge, New York. Temperature and dewpoint temperature measurements were collected by three microclimate stations both within (two stations) and just outside (one station) of the gorge during the months of September and November. A total of nine cold fronts passed over the gorge at different times of day (i.e., daytime, nighttime, and transitional) during the eight-week measurement period. During the prefrontal time periods, the two sites within the gorge were similar in both temperature and moisture content: colder and greater moisture content compared to the outside-gorge site. A stable inversion layer was present at the rim height of the gorge a large percentage of time resulting in limited mixing and a separation of the outside-gorge and inside-gorge atmospheres. Following the passage of cold fronts, there was a robust transition to a large-scale colder atmospheric air mass across the central New York region and introduction of less stable conditions that allowed intrusion and mixing of outside-gorge air within the complex terrain of Watkins Glen gorge, especially during nighttime and transitional cold fronts.
{"title":"Influence of cold fronts on microscale atmospheric conditions within the complex terrain of Watkins Glen Gorge, New York","authors":"Chad W. Hecht, Neil F Laird","doi":"10.1080/02723646.2021.1938923","DOIUrl":"https://doi.org/10.1080/02723646.2021.1938923","url":null,"abstract":"ABSTRACT This study investigates the influence of synoptic-scale cold fronts on microclimatic conditions within the complex terrain of Watkins Glen gorge, New York. Temperature and dewpoint temperature measurements were collected by three microclimate stations both within (two stations) and just outside (one station) of the gorge during the months of September and November. A total of nine cold fronts passed over the gorge at different times of day (i.e., daytime, nighttime, and transitional) during the eight-week measurement period. During the prefrontal time periods, the two sites within the gorge were similar in both temperature and moisture content: colder and greater moisture content compared to the outside-gorge site. A stable inversion layer was present at the rim height of the gorge a large percentage of time resulting in limited mixing and a separation of the outside-gorge and inside-gorge atmospheres. Following the passage of cold fronts, there was a robust transition to a large-scale colder atmospheric air mass across the central New York region and introduction of less stable conditions that allowed intrusion and mixing of outside-gorge air within the complex terrain of Watkins Glen gorge, especially during nighttime and transitional cold fronts.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1938923","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45828340","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}
Pub Date : 2021-07-01DOI: 10.1080/02723646.2021.1944462
P. Barrineau, V. P. Tchakerian
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.
{"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":null,"pages":null},"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}
Pub Date : 2021-06-30DOI: 10.1080/02723646.2021.1938501
A. Lone, Shubhra Sharma, H. Achyuthan, A. Shukla, R. Shah, S. Sangode, F. A. A.
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.
亚洲中纬度地区的黄土-古土壤代用记录有助于重建区域古气候演变及其与全球气候变化的关系。本研究探讨了西北喜马拉雅赞斯卡尔山脉南部黄土-古土壤序列(LPS)的离散产状。沉积物结构的地层变化，加上地球化学、有机和磁性指标，表明黄土增生(L-1)和古土壤形成(PS-1)两大阶段。古黄土(L-1)沉积期在2.5±0.3 ka ~ >2.0 ka之间，而完全转变为现代土壤(MS)的黄土(L-2)沉积期可能在小冰期(LIA)。黄土的结构特征(含砂量高)表明其源近端沉积，而地球化学和磁性指标则表明其沉积前风化作用(在源区)。PS-1测定值为2189±296 calyr BP，表明水汽条件有所改善，而MS测定值为LIA后暖相。这些发现为更好地理解SZR黄土增生和古土壤形成与晚全新世气候变率的敏感性提供了重要的一步。
{"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":null,"pages":null},"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}
Pub Date : 2021-06-20DOI: 10.1080/02723646.2021.1936790
J. Ollerhead, R. Davidson-Arnott
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.
{"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":null,"pages":null},"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}
Pub Date : 2021-06-07DOI: 10.1080/02723646.2021.1934957
C. Day, J. Liebman
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.
{"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":null,"pages":null},"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}
Pub Date : 2021-06-07DOI: 10.1080/02723646.2021.1930654
Mekonnen Adnew Degefu, Yonas T. Tadesse, W. Bewket
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.
{"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":null,"pages":null},"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}
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