Pub Date : 2021-05-11DOI: 10.1080/02723646.2021.1923368
Santiago Cataño-Álvarez
ABSTRACT Incising gravel channels respond with a robust critical transition to the lateral alluvial supply. Previous experiments have studied how supply affects bedload transport, but I studied a setup with converging banks, where the supply–transport relation implies feedback. While increasing flows, a short range of transitional flows showed sharp increase of bedload, accompanied by channel response via longitudinal homogenization (connectivity) and maximum sediment storage. To slightly vary initial bed mixing (channel history), I repeated the experiments three times, which validated the robustness of the transition. This transition synchronized hydraulics and transport along the channel, leading to a wetted width consistent with downstream hydraulic geometry that allowed a critical sediment evacuation with minimum energy and bed alteration. For flows higher than the transitional, longitudinal connectivity persisted, as most of the landslide material was redistributed by fluvial action. Finally, the largest flows dissipated energy excess via coarsening and channel migration, akin to non-incising rivers with floodplain. A conceptual model of the geomorphic cycle of gravel river reaches might contain the proposed critical transition, but only if this transition proves to be robust to bank cohesion and to spatial and temporal size of the experimental setup.
{"title":"Critical transition of incising gravel channel to evacuate alluvial lateral supply","authors":"Santiago Cataño-Álvarez","doi":"10.1080/02723646.2021.1923368","DOIUrl":"https://doi.org/10.1080/02723646.2021.1923368","url":null,"abstract":"ABSTRACT Incising gravel channels respond with a robust critical transition to the lateral alluvial supply. Previous experiments have studied how supply affects bedload transport, but I studied a setup with converging banks, where the supply–transport relation implies feedback. While increasing flows, a short range of transitional flows showed sharp increase of bedload, accompanied by channel response via longitudinal homogenization (connectivity) and maximum sediment storage. To slightly vary initial bed mixing (channel history), I repeated the experiments three times, which validated the robustness of the transition. This transition synchronized hydraulics and transport along the channel, leading to a wetted width consistent with downstream hydraulic geometry that allowed a critical sediment evacuation with minimum energy and bed alteration. For flows higher than the transitional, longitudinal connectivity persisted, as most of the landslide material was redistributed by fluvial action. Finally, the largest flows dissipated energy excess via coarsening and channel migration, akin to non-incising rivers with floodplain. A conceptual model of the geomorphic cycle of gravel river reaches might contain the proposed critical transition, but only if this transition proves to be robust to bank cohesion and to spatial and temporal size of the experimental setup.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"44 1","pages":"1 - 30"},"PeriodicalIF":1.6,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1923368","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43222193","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 : 2021-05-04DOI: 10.1080/02723646.2021.1919379
R. Dorn
ABSTRACT Biological soil crusts (BSCs) monitored over a 25-year period enhance the dissolution of the Ca-silicate plagioclase and the Mg-silicate olivine at Sonoran Desert and Colorado Plateau, USA, study sites. This first measured biological enhancement of weathering (BEW) for plagioclase is a mean of 2.3±0.4 and 3.0±0.4 for the Organic Pipe, Arizona and Moab, Utah study sites; and it is 4.9±0.8 and 3.9±0.3 for olivine at these respective sites. These BEWs are low compared to other biological agents such as lichens, tree roots, termites and especially ants. If these modern BEW for BCSs reflect the magnitude of BEW in Archean soil crusts, then the presence of abundant BSCs covering an Archean Earth surface would not contradict available evidence for no substantial atmospheric CO2 decline in Earth’s early atmosphere. The relatively low BEW value for BCSs indicates that BSCs would not be a useful geoengineering solution to high levels of atmospheric carbon dioxide.
{"title":"Assessing biological soil crusts as agents of Ca–Mg silicate dissolution and CO2 sequestration","authors":"R. Dorn","doi":"10.1080/02723646.2021.1919379","DOIUrl":"https://doi.org/10.1080/02723646.2021.1919379","url":null,"abstract":"ABSTRACT Biological soil crusts (BSCs) monitored over a 25-year period enhance the dissolution of the Ca-silicate plagioclase and the Mg-silicate olivine at Sonoran Desert and Colorado Plateau, USA, study sites. This first measured biological enhancement of weathering (BEW) for plagioclase is a mean of 2.3±0.4 and 3.0±0.4 for the Organic Pipe, Arizona and Moab, Utah study sites; and it is 4.9±0.8 and 3.9±0.3 for olivine at these respective sites. These BEWs are low compared to other biological agents such as lichens, tree roots, termites and especially ants. If these modern BEW for BCSs reflect the magnitude of BEW in Archean soil crusts, then the presence of abundant BSCs covering an Archean Earth surface would not contradict available evidence for no substantial atmospheric CO2 decline in Earth’s early atmosphere. The relatively low BEW value for BCSs indicates that BSCs would not be a useful geoengineering solution to high levels of atmospheric carbon dioxide.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"42 1","pages":"529 - 541"},"PeriodicalIF":1.6,"publicationDate":"2021-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1919379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49206840","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 : 2021-04-14DOI: 10.1080/02723646.2021.1899478
S. Yadav, Sudhir Kumar Singh
ABSTRACT The morpho-tectonic characteristics of the study area were evaluated due to paleo-tectonic significance. The Upper Tons Basin is associated with the Ganga river system, originated over the fracture zones produced after the collision of Indian and Eurasian plates; hence, the study region has its tectonic importance with small-scale tectonic deformation. The relief, drainage and tectonic characteristics are analyzed by using digital elevation model and topographical maps, geomorphic indices, lineaments and transverse profiles. Result reveals that two-third areas are in declining from mature stage (H I < 0.50) or monadnock phase (H I < 0.40). The value of basin asymmetry factor is suggesting right-side tilting of the trunk stream due to the tributaries of the Tons river originating over the Bhander uplands being longer. Further, the comparison of the stream length gradient with normalized stream length gradient shows delineating tectonically anomalous regions, and the anomalous points are addressed in the longitudinal profiles. The scarps fronts of the plateau are more sinuous and highly eroded, while the straight Kaimur fronts indicate relatively sensitive fronts. The relative tectonic activity index helps to evaluate the potential tectonic activity of a drainage basin and drainage network developed over the tectonically pre-designed valley.
从古构造意义出发，评价了研究区形态构造特征。上顿盆地与恒河水系有关，起源于印度板块与欧亚板块碰撞后形成的断裂带;因此，研究区具有小尺度构造变形的重要意义。利用数字高程模型、地形图、地貌指数、地貌线和横向剖面图，分析了该地区的地形、水系和构造特征。结果表明，三分之二的地区从成熟期(H I < 0.50)或单峰期(H I < 0.40)开始呈下降趋势。流域不对称因子的值表明，由于发源于班德勒高地的顿斯河支流较长，干流向右侧倾斜。通过与归一化长度梯度的对比，圈定了构造异常区域，并在纵剖面上对异常点进行了定位。高原的陡坡锋面较为曲折，侵蚀程度较高，而直线型的凯木尔锋面较为敏感。相对构造活动指数有助于评价在构造预先设计的河谷上发育的流域盆地和流域网络的潜在构造活动。
{"title":"Morpho-tectonic assessment of Central Northern escarpment of Peninsular India, based on tectonically sensitive geomorphic indices","authors":"S. Yadav, Sudhir Kumar Singh","doi":"10.1080/02723646.2021.1899478","DOIUrl":"https://doi.org/10.1080/02723646.2021.1899478","url":null,"abstract":"ABSTRACT The morpho-tectonic characteristics of the study area were evaluated due to paleo-tectonic significance. The Upper Tons Basin is associated with the Ganga river system, originated over the fracture zones produced after the collision of Indian and Eurasian plates; hence, the study region has its tectonic importance with small-scale tectonic deformation. The relief, drainage and tectonic characteristics are analyzed by using digital elevation model and topographical maps, geomorphic indices, lineaments and transverse profiles. Result reveals that two-third areas are in declining from mature stage (H I < 0.50) or monadnock phase (H I < 0.40). The value of basin asymmetry factor is suggesting right-side tilting of the trunk stream due to the tributaries of the Tons river originating over the Bhander uplands being longer. Further, the comparison of the stream length gradient with normalized stream length gradient shows delineating tectonically anomalous regions, and the anomalous points are addressed in the longitudinal profiles. The scarps fronts of the plateau are more sinuous and highly eroded, while the straight Kaimur fronts indicate relatively sensitive fronts. The relative tectonic activity index helps to evaluate the potential tectonic activity of a drainage basin and drainage network developed over the tectonically pre-designed valley.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"753 - 783"},"PeriodicalIF":1.6,"publicationDate":"2021-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1899478","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49005433","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 : 2021-04-02DOI: 10.1080/02723646.2021.1904698
S. Burak, A. Bilge, Duygu Ülker
ABSTRACT The population of Istanbul increased from three to fifteen million from 1970 to 2018. The city, which has no perennial fresh water resources within its metropolitan boundaries, has long imported water from other basins. In this study, the performance of a reservoir system fed by surface runoff and inter-basin water transfer is investigated and applied. Simulations are run for water demand estimates and with Gamma-distributed realizations of monthly precipitation, based on 105-year temperature and precipitation data. The research shows that after 2060, existing and transferred water alone will not be sufficient to meet demand and it is expected that the megacity Istanbul will be on a path towards water crisis after this date, if not before. It is concluded that it is vital to adopt a more diversified water supply and demand management portfolio with extensive Integrated Water Resources Management (IWRM) measures for “Water Sensitive Cities”. Strategies for reliable system operation that take foreseeable environmental problems into account are proposed.
{"title":"Assessment and simulation of water transfer for the megacity Istanbul","authors":"S. Burak, A. Bilge, Duygu Ülker","doi":"10.1080/02723646.2021.1904698","DOIUrl":"https://doi.org/10.1080/02723646.2021.1904698","url":null,"abstract":"ABSTRACT The population of Istanbul increased from three to fifteen million from 1970 to 2018. The city, which has no perennial fresh water resources within its metropolitan boundaries, has long imported water from other basins. In this study, the performance of a reservoir system fed by surface runoff and inter-basin water transfer is investigated and applied. Simulations are run for water demand estimates and with Gamma-distributed realizations of monthly precipitation, based on 105-year temperature and precipitation data. The research shows that after 2060, existing and transferred water alone will not be sufficient to meet demand and it is expected that the megacity Istanbul will be on a path towards water crisis after this date, if not before. It is concluded that it is vital to adopt a more diversified water supply and demand management portfolio with extensive Integrated Water Resources Management (IWRM) measures for “Water Sensitive Cities”. Strategies for reliable system operation that take foreseeable environmental problems into account are proposed.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"784 - 808"},"PeriodicalIF":1.6,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1904698","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45385918","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 : 2021-03-31DOI: 10.1080/02723646.2021.1905594
N. Mohseni, S. Hosseinzadeh
ABSTRACT We evaluated the impacts of the interactions among hydro-aeolian processes and micro-geomorphology on mechanisms controlling the sediment carbon source and sink within a coppice dune. The sediment sampling process was performed within different positions of each dune. Sediment grain size distribution, geometric mean diameter, mean weight diameter, labile SOC, CO2 flux, and C mineralization ratio were measured. The finest sediments were observed on the dune edge. The labile SOC and CO2 flux rate showed an increasing trend in the edge, windward, and top positions. However, the C mineralization ratio decreased only in the dune edge. A significant increase of clay fractions at the dune edge can result from the horizontal sediment transport by runoff from the interdune area to the dune. The SOC could bond with clay fractions to contribute toward the formation of soil aggregation, causing less vulnerability of SOC to microbial respiration. A significant increase of sand fractions, transported by the aeolian process, on the top and windward positions could not protect SOC against decomposition. The interactions among hydro-aeolian processes and micro-geomorphology could encourage the hot spots of sediment carbon reservoirs within the dryland landforms that have a significant proportion in the exchange of carbon to the atmosphere.
{"title":"Interactions among hydro-aeolian processes and micro-geomorphology stimulate hot spots of sediment carbon source and sink within a coppice dune system","authors":"N. Mohseni, S. Hosseinzadeh","doi":"10.1080/02723646.2021.1905594","DOIUrl":"https://doi.org/10.1080/02723646.2021.1905594","url":null,"abstract":"ABSTRACT We evaluated the impacts of the interactions among hydro-aeolian processes and micro-geomorphology on mechanisms controlling the sediment carbon source and sink within a coppice dune. The sediment sampling process was performed within different positions of each dune. Sediment grain size distribution, geometric mean diameter, mean weight diameter, labile SOC, CO2 flux, and C mineralization ratio were measured. The finest sediments were observed on the dune edge. The labile SOC and CO2 flux rate showed an increasing trend in the edge, windward, and top positions. However, the C mineralization ratio decreased only in the dune edge. A significant increase of clay fractions at the dune edge can result from the horizontal sediment transport by runoff from the interdune area to the dune. The SOC could bond with clay fractions to contribute toward the formation of soil aggregation, causing less vulnerability of SOC to microbial respiration. A significant increase of sand fractions, transported by the aeolian process, on the top and windward positions could not protect SOC against decomposition. The interactions among hydro-aeolian processes and micro-geomorphology could encourage the hot spots of sediment carbon reservoirs within the dryland landforms that have a significant proportion in the exchange of carbon to the atmosphere.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"487 - 502"},"PeriodicalIF":1.6,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1905594","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42688932","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 : 2021-03-31DOI: 10.1080/02723646.2021.1907883
Amit Shoshta, B. S. Marh
ABSTRACT Pin valley is an ideal area for alluvial fans’ development. Being least disturbed and devoid of vegetation, fans of this area provide exquisite information and extraordinary opportunity to understand different factors that affect their morphology. Despite aforesaid advantages these fans are hitherto not studied. Thus, the present study is an attempt to understand the morphology of these fans and explore factors affecting fan morphology, primarily through morphometry. Data were derived from various satellite imageries, topographical sheets, DEM and field observations. Various parameters of 51 fans and of their basins were measured and relationships among different parameters were examined. The results of the study are generally comparable to literature though these fans are much steeper than their counterparts in similar environmental settings. Multi-proxy approach was used to explore controlling factors. Fan Conicality Index (FCI) and sweep angle of fan (SA ) suggest confinement imposed by surrounding environment has considerably reduced the size of these fans. Further, valley-floor width to height ratio (Vf ), feeder channel and geological group-wise analyses reveal that active tectonic attitude, order of feeder channel, lithology and characteristics of contributing basin along with associated depositional processes exercise significant control on morphology of these fans.
{"title":"Alluvial fans of Trans-Himalayan cold desert (Pin valley, India): quantitative morphology and controlling factors","authors":"Amit Shoshta, B. S. Marh","doi":"10.1080/02723646.2021.1907883","DOIUrl":"https://doi.org/10.1080/02723646.2021.1907883","url":null,"abstract":"ABSTRACT Pin valley is an ideal area for alluvial fans’ development. Being least disturbed and devoid of vegetation, fans of this area provide exquisite information and extraordinary opportunity to understand different factors that affect their morphology. Despite aforesaid advantages these fans are hitherto not studied. Thus, the present study is an attempt to understand the morphology of these fans and explore factors affecting fan morphology, primarily through morphometry. Data were derived from various satellite imageries, topographical sheets, DEM and field observations. Various parameters of 51 fans and of their basins were measured and relationships among different parameters were examined. The results of the study are generally comparable to literature though these fans are much steeper than their counterparts in similar environmental settings. Multi-proxy approach was used to explore controlling factors. Fan Conicality Index (FCI) and sweep angle of fan (SA ) suggest confinement imposed by surrounding environment has considerably reduced the size of these fans. Further, valley-floor width to height ratio (Vf ), feeder channel and geological group-wise analyses reveal that active tectonic attitude, order of feeder channel, lithology and characteristics of contributing basin along with associated depositional processes exercise significant control on morphology of these fans.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"44 1","pages":"136 - 161"},"PeriodicalIF":1.6,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1907883","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43625190","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 : 2021-03-23DOI: 10.1080/02723646.2021.1899477
Altanbold Enkhbold, U. Khukhuudei, T. Kusky, B. Tsermaa, Dash Doljin
ABSTRACT Data on the origin and morphology of lake depressions in Mongolia are relatively poor. Bayan Lake in Zavkhan Province, Western Mongolia, has freshwater, supplied by groundwater emanating from a tectonic fault-oriented northeast to southwest, defining the southeastern side of the Bayan Lake. The depression of Bayan Lake has a tectonic origin, related with the fault which on its southern side, which is covered by sand dunes. The results of morphometric analysis, satellite mapping, geomagnetic anomaly assessment, and other relevant methods all support that the southern margin of the lake is defined by a large fault. The depression morphology of Bayan Lake shows that it was formed by subsidence accommodated by the fault along the southwestern side of the lake. Bayan Lake depression has the origin tectonic, but the recent barrier in the south is the dunefield on the bedrock.
{"title":"Depression morphology of Bayan Lake, Zavkhan province, Western Mongolia: implications for the origin of lake depression in Mongolia","authors":"Altanbold Enkhbold, U. Khukhuudei, T. Kusky, B. Tsermaa, Dash Doljin","doi":"10.1080/02723646.2021.1899477","DOIUrl":"https://doi.org/10.1080/02723646.2021.1899477","url":null,"abstract":"ABSTRACT Data on the origin and morphology of lake depressions in Mongolia are relatively poor. Bayan Lake in Zavkhan Province, Western Mongolia, has freshwater, supplied by groundwater emanating from a tectonic fault-oriented northeast to southwest, defining the southeastern side of the Bayan Lake. The depression of Bayan Lake has a tectonic origin, related with the fault which on its southern side, which is covered by sand dunes. The results of morphometric analysis, satellite mapping, geomagnetic anomaly assessment, and other relevant methods all support that the southern margin of the lake is defined by a large fault. The depression morphology of Bayan Lake shows that it was formed by subsidence accommodated by the fault along the southwestern side of the lake. Bayan Lake depression has the origin tectonic, but the recent barrier in the south is the dunefield on the bedrock.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"727 - 752"},"PeriodicalIF":1.6,"publicationDate":"2021-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1899477","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49185146","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 : 2021-03-23DOI: 10.1080/02723646.2021.1899476
Karla Aurora De La Peña Guillen, M. Mendoza, J. L. Macías, Berenice Solís‐Castillo
ABSTRACT Landslides are one of the most common and destructive natural hazards in the world. The Sierra-Costa region in the southwestern part of the Michoacán state, Mexico, is prone to landslides because of its physiography, geology, and climate. In particular, the area is prone to shallow landslides in the weathered rock that is triggered by heavy rainfall. Here, we present a susceptibility model for this hazard that is based on an analytical hierarchy process (AHP). To assess landslide susceptibility, we designed maps of different parameters (lithology, distance to faults, slope gradient, slope aspect, geoforms, soil type, distance to rivers, and land cover). The landslide susceptibility map includes five classes: nullnull, low, moderate, high, and very high susceptibility. About 5% of the area is categorized as having null landslide susceptibility class; 18% is low susceptibility, 28% moderate susceptibility, 29% high susceptibility, and 20% very high susceptibility. The very high susceptibility areas are dominantly underlain by limestone and weathered granite and are near faults. We evaluated the precision of the model using the receiver operating characteristic (ROC) curve method. The susceptibility model represents the first step in understanding the distribution of landslides in the Sierra-Costa region.
{"title":"Landslide susceptibility analysis based on a semiquantitative method in the sierra-costa region, michoacán, mexico","authors":"Karla Aurora De La Peña Guillen, M. Mendoza, J. L. Macías, Berenice Solís‐Castillo","doi":"10.1080/02723646.2021.1899476","DOIUrl":"https://doi.org/10.1080/02723646.2021.1899476","url":null,"abstract":"ABSTRACT Landslides are one of the most common and destructive natural hazards in the world. The Sierra-Costa region in the southwestern part of the Michoacán state, Mexico, is prone to landslides because of its physiography, geology, and climate. In particular, the area is prone to shallow landslides in the weathered rock that is triggered by heavy rainfall. Here, we present a susceptibility model for this hazard that is based on an analytical hierarchy process (AHP). To assess landslide susceptibility, we designed maps of different parameters (lithology, distance to faults, slope gradient, slope aspect, geoforms, soil type, distance to rivers, and land cover). The landslide susceptibility map includes five classes: nullnull, low, moderate, high, and very high susceptibility. About 5% of the area is categorized as having null landslide susceptibility class; 18% is low susceptibility, 28% moderate susceptibility, 29% high susceptibility, and 20% very high susceptibility. The very high susceptibility areas are dominantly underlain by limestone and weathered granite and are near faults. We evaluated the precision of the model using the receiver operating characteristic (ROC) curve method. The susceptibility model represents the first step in understanding the distribution of landslides in the Sierra-Costa region.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"43 1","pages":"463 - 486"},"PeriodicalIF":1.6,"publicationDate":"2021-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1899476","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48358470","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 : 2021-03-19DOI: 10.1080/02723646.2021.1893142
Raven J. Mitchell, F. Nelson, K. Nyland
ABSTRACT Nivation, the suite of weathering and transportation processes attributed to late-lying snowpatches, is linked to the formation of cryoplanation terraces (CTs). CTs resemble giant staircases arranged in repeating sequences of low-gradient treads and steep scarps that extend over hundreds of meters. The nivation hypothesis of CT development has been supported in recent literature examining weathering and erosion trends, but the mechanisms involved in transporting sediment across CT treads remain underinvestigated. Sorted stripes, a type of patterned ground encountered on CT treads, have been linked to efficient snow meltwater flow across low gradients, indicating that these features could be an important component of CT formation. In this study, we use short-term soil thermal and moisture records, particle-size analysis, and apparent thermal diffusivity calculations to examine periglacial processes operating on two incipient CTs. Initial results indicate that: (1) the coarse (boulder and cobble size) portions of sorted stripes function as subsurface channels for sediment transportation across gently sloping CT treads (generally < 12°) by flowing water; (2) hillslope hydrology is an important component of the erosion processes sculpting upland periglacial environments; and (3) late-lying snowbank environments are highly dynamic during warm weather, with large amounts of sediment transported over short periods.
{"title":"Preliminary observations of nivation processes, Cathedral Massif, Northwestern British Columbia, Canada","authors":"Raven J. Mitchell, F. Nelson, K. Nyland","doi":"10.1080/02723646.2021.1893142","DOIUrl":"https://doi.org/10.1080/02723646.2021.1893142","url":null,"abstract":"ABSTRACT Nivation, the suite of weathering and transportation processes attributed to late-lying snowpatches, is linked to the formation of cryoplanation terraces (CTs). CTs resemble giant staircases arranged in repeating sequences of low-gradient treads and steep scarps that extend over hundreds of meters. The nivation hypothesis of CT development has been supported in recent literature examining weathering and erosion trends, but the mechanisms involved in transporting sediment across CT treads remain underinvestigated. Sorted stripes, a type of patterned ground encountered on CT treads, have been linked to efficient snow meltwater flow across low gradients, indicating that these features could be an important component of CT formation. In this study, we use short-term soil thermal and moisture records, particle-size analysis, and apparent thermal diffusivity calculations to examine periglacial processes operating on two incipient CTs. Initial results indicate that: (1) the coarse (boulder and cobble size) portions of sorted stripes function as subsurface channels for sediment transportation across gently sloping CT treads (generally < 12°) by flowing water; (2) hillslope hydrology is an important component of the erosion processes sculpting upland periglacial environments; and (3) late-lying snowbank environments are highly dynamic during warm weather, with large amounts of sediment transported over short periods.","PeriodicalId":54618,"journal":{"name":"Physical Geography","volume":"42 1","pages":"513 - 528"},"PeriodicalIF":1.6,"publicationDate":"2021-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02723646.2021.1893142","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49563690","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 : 2021-02-25DOI: 10.1080/02723646.2021.1890894
Rachel Lombardi, L. Davis, M. Therrell
ABSTRACT Heavy precipitation events increased over the last century in response to higher atmospheric temperature and associated increases in water vapor content, but little evidence shows that increased heavy precipitation changed flood trends. Short records, containing few extreme flood observations, limit statistical examination of relationships between global temperature, heavy precipitation, and extreme floods. We synthesized European and North American sediment-based paleoflood records extending through at least 900 CE. These records captured flood variability during the warmer Medieval Climate Anomaly (MCA) and cooler Little Ice Age (LIA). Twelve paleoflood chronologies chosen for the analysis suggest an increase in flood frequency since 1000 CE. The largest magnitude floods mostly occurred between 1000 and 1300 CE after peak MCA temperature during a relatively drier overall climate regime. The association found between large magnitude floods during a drier climate may be explained by increased atmospheric water vapor capacity from warmer temperatures that intensified precipitation events. Despite limitations in the number of studies available, extreme flood observations reveal a pattern of large magnitude floods in the late MCA and frequent floods in the LIA. Therefore, temperature–precipitation relationships may influence flood variability, and flood magnitude will likely become more extreme as global temperatures rise.
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