N. Evelpidou, T. Gournelos, A. Karkani, Eirini Kardara
In this paper we attempt to classify drainage sub-basins according to their erosion risk. We have adopted a multistep procedure to face this problem. The input variables were introduced into a GIS – platform. These variables were the vulnerability of the surface rocks to erosion, topographic variations, vegetation cover, land use and drainage basin characteristics. We constructed a fuzzy inference mechanism to pre-process the input variables. Next we used neural–network technology to process the input variables. The system was trained to ‘learn’ and classify the input data. The output of this procedure was a classification of the sub-drainage basins related to their risk of erosion. This neuro–fuzzy system was applied to the island of Lefkas (Greece).
{"title":"Developing a neuro–fuzzy system to classify drainage sub-basins according to erosion processes on the Island of Lefkas, Greece","authors":"N. Evelpidou, T. Gournelos, A. Karkani, Eirini Kardara","doi":"10.21094/RG.2018.025","DOIUrl":"https://doi.org/10.21094/RG.2018.025","url":null,"abstract":"In this paper we attempt to classify drainage sub-basins according to their erosion risk. We have adopted a multistep procedure to face this problem. The input variables were introduced into a GIS – platform. These variables were the vulnerability of the surface rocks to erosion, topographic variations, vegetation cover, land use and drainage basin characteristics. We constructed a fuzzy inference mechanism to pre-process the input variables. Next we used neural–network technology to process the input variables. The system was trained to ‘learn’ and classify the input data. The output of this procedure was a classification of the sub-drainage basins related to their risk of erosion. This neuro–fuzzy system was applied to the island of Lefkas (Greece).","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41333545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study was performed in order to quantify soil erosion in the arid lands of central Tunisia. To do this we used geographic information systems, remote sensing and the RUSLE prediction model. While the study area is characterized by reduced rainfall quantities and therefore a low R factor, other factors such as high soil erodibility, low vegetation cover and steep slopes resulted in locally high erosion rates. Indeed, the calculation of RUSLE factors revealed values between 0 and 731 tones×ha-1×year-1 with an average of 3.84 tones×ha-1×year-1. Whereas most catchment lands have low levels, the relief surrounding the catchment has relatively high rates due to the high value of slopes, the skeletal soils that compose them, but also due to the absence of protection, reforestation or crop management. This study also showed that despite their small extension compared to the watershed, main streams sectors, and especially their banks, record the highest erosion rates mainly due to the flow accumulation in the downstream sectors. Relative protection of the piedmont, which has saved them from higher erosion, can only be considered efficient and sustainable if the upstream hillsides are also protected. The comparison with previous studies carried out in Tunisia shows similarities in the results of some of them, considering the natural geographical variation of the R factor.
{"title":"Quantifying water erosion hazard in central Tunisia A case study: the Leben watershed","authors":"Chokri Bedoui","doi":"10.21094/RG.2018.041","DOIUrl":"https://doi.org/10.21094/RG.2018.041","url":null,"abstract":"This study was performed in order to quantify soil erosion in the arid lands of central Tunisia. To do this we used geographic information systems, remote sensing and the RUSLE prediction model. While the study area is characterized by reduced rainfall quantities and therefore a low R factor, other factors such as high soil erodibility, low vegetation cover and steep slopes resulted in locally high erosion rates. Indeed, the calculation of RUSLE factors revealed values between 0 and 731 tones×ha-1×year-1 with an average of 3.84 tones×ha-1×year-1. Whereas most catchment lands have low levels, the relief surrounding the catchment has relatively high rates due to the high value of slopes, the skeletal soils that compose them, but also due to the absence of protection, reforestation or crop management. This study also showed that despite their small extension compared to the watershed, main streams sectors, and especially their banks, record the highest erosion rates mainly due to the flow accumulation in the downstream sectors. Relative protection of the piedmont, which has saved them from higher erosion, can only be considered efficient and sustainable if the upstream hillsides are also protected. The comparison with previous studies carried out in Tunisia shows similarities in the results of some of them, considering the natural geographical variation of the R factor.","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42858675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper assesses the possibility of permafrost occurrence in Iezer Mountains using field observations, GIS analysis and thermal investigations in the field. Rock glaciers as the main mountain permafrost footprint in the landscape are mapped using cross validation from two independent inventories, analysed and classified in terms of size, altitude, morphology, air temperature and vegetation cover. Measurements of spring temperatures, bottom temperature of snow (BTS) and continuous (near) ground surface temperature (GST) were applied to check for permafrost presence. Autumn temperature of 20 alpine springs are analysed and grouped by their source, temperature and apparent discharges. BTS was applied on 3 sites from the upper part of Colților Valley in 2012 and 2018 along GST in Tambura scree in 2012–2018 period. 16 rock glaciers are considered to exist in Iezer Massif, a much smaller number than previously assumed. We argue that several other landforms are rock–ice features and should be inventoried and analysed in corresponding with minimal past permafrost creep. Rock glaciers are poorly developed and have a faded morphology because of low debris availability, short periods of time with favourable climates and less supportive mountain morphometry. Alpine springs indicate possible permafrost occurrence in one rock glacier and one talus slope and BTS reveal sporadic patches of permafrost down to 1900 m asl in Colților Valley. GST supports the multiannual stability of permafrost indicating BTS on a multiannual scale and suggests the great importance of autumn–early winter temperatures and snow interplay for ground cooling and permafrost maintenance. We argue that 11 rock glaciers from Iezer Mountains are probably inactive. MAGST of 1.1 – 3.2 °C suggest a strong thermal gradient in the blocky layer if permafrost is truly present. Alpine screes possibly underlain by permafrost seem not to be disturbed by any modern climate changes.
{"title":"Permafrost investigations in Iezer Mountains, Southern Carpathians","authors":"R. Popescu","doi":"10.21094/RG.2018.033","DOIUrl":"https://doi.org/10.21094/RG.2018.033","url":null,"abstract":"This paper assesses the possibility of permafrost occurrence in Iezer Mountains using field observations, GIS analysis and thermal investigations in the field. Rock glaciers as the main mountain permafrost footprint in the landscape are mapped using cross validation from two independent inventories, analysed and classified in terms of size, altitude, morphology, air temperature and vegetation cover. Measurements of spring temperatures, bottom temperature of snow (BTS) and continuous (near) ground surface temperature (GST) were applied to check for permafrost presence. Autumn temperature of 20 alpine springs are analysed and grouped by their source, temperature and apparent discharges. BTS was applied on 3 sites from the upper part of Colților Valley in 2012 and 2018 along GST in Tambura scree in 2012–2018 period. 16 rock glaciers are considered to exist in Iezer Massif, a much smaller number than previously assumed. We argue that several other landforms are rock–ice features and should be inventoried and analysed in corresponding with minimal past permafrost creep. Rock glaciers are poorly developed and have a faded morphology because of low debris availability, short periods of time with favourable climates and less supportive mountain morphometry. Alpine springs indicate possible permafrost occurrence in one rock glacier and one talus slope and BTS reveal sporadic patches of permafrost down to 1900 m asl in Colților Valley. GST supports the multiannual stability of permafrost indicating BTS on a multiannual scale and suggests the great importance of autumn–early winter temperatures and snow interplay for ground cooling and permafrost maintenance. We argue that 11 rock glaciers from Iezer Mountains are probably inactive. MAGST of 1.1 – 3.2 °C suggest a strong thermal gradient in the blocky layer if permafrost is truly present. Alpine screes possibly underlain by permafrost seem not to be disturbed by any modern climate changes.","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43585411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mihai Niculiță, Valeriu Stoilov-Linu, Nicușor Necula
The creation and analysis of landslide inventories is the basic approach for starting the landslide hazard to risk analysis chain analysis. In order to perform this kind of analysis for the Iași Municipality (North–eastern Romania) we created based on aerial imagery and LiDAR data a landslide inventory of the landslide events that happened in the last 100 years. In total, we identified and delineated 518 landslide events: 51.5% translational slides, 19.7% slumps (rotational slides), 17% flowslides and 11.8% flows. The majority (74%) of the landslides events happened between 1956 and 1984, those before 1956 representing 16%, while those triggered after 1984 representing 10%. This situation reflects the very humid period between 1960 and 1990, when the majority of the landslide events were triggered. Beside the typology we have also identified the triggering factors and we can conclude that rainstorms coupled with previous rainy years were the main triggering factors, especially for Holocene old and relict landslides in areas with land use and anthropic disturbances created by the built up area expansion. The analysis of the landslide area frequency density is showing that the shape of the distribution curve is similar with what was reported in the literature, which is signaling that this inventory can be used further in landslide susceptibility modelling and validation. Further analysis of these events can also pinpoint scenarios for vulnerability and riskanalysis.
{"title":"Recent landslides from Iași Metropolitan Area","authors":"Mihai Niculiță, Valeriu Stoilov-Linu, Nicușor Necula","doi":"10.21094/RG.2018.030","DOIUrl":"https://doi.org/10.21094/RG.2018.030","url":null,"abstract":"The creation and analysis of landslide inventories is the basic approach for starting the landslide hazard to risk analysis chain analysis. In order to perform this kind of analysis for the Iași Municipality (North–eastern Romania) we created based on aerial imagery and LiDAR data a landslide inventory of the landslide events that happened in the last 100 years. In total, we identified and delineated 518 landslide events: 51.5% translational slides, 19.7% slumps (rotational slides), 17% flowslides and 11.8% flows. The majority (74%) of the landslides events happened between 1956 and 1984, those before 1956 representing 16%, while those triggered after 1984 representing 10%. This situation reflects the very humid period between 1960 and 1990, when the majority of the landslide events were triggered. Beside the typology we have also identified the triggering factors and we can conclude that rainstorms coupled with previous rainy years were the main triggering factors, especially for Holocene old and relict landslides in areas with land use and anthropic disturbances created by the built up area expansion. The analysis of the landslide area frequency density is showing that the shape of the distribution curve is similar with what was reported in the literature, which is signaling that this inventory can be used further in landslide susceptibility modelling and validation. Further analysis of these events can also pinpoint scenarios for vulnerability and riskanalysis.","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46661377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The administrative territory of Cluj–Napoca, due to its specific geological and geomorphological characteristics and anthropic activities, has been affected for a long time by landslides. Thus, it becomes necessary to analyse affected areas with different spatial methods, with the aim of generating landslide susceptibility maps. In this research, we studied the most prone area of the city, the Becaș stream watershed, situated in the Southern part of the municipality. The aim of this paper is to generate a valid susceptibility map, to be able to raise awareness about the existing situation: due to human induced activities and rapid urban growth, the peripheral part of Cluj–Napoca becomes more and more prone to mass–movements. We used the maximum entropy (MaxEnt) model, which was fed with accurate information on the existing landslides and seven landslide–causing factors: slope, aspect, land–use, depth of fragmentation, geology and plan– and profile curvature. The results confirm that the most influential factors are the land use and slope–angle, affected in a large degree by human activities. The accuracy of the generated map was verified using the AUC method, proving a very good performance (0.844) of the applied model.
{"title":"Landslide susceptibility assessment using the maximum entropy model in a sector of the Cluj–Napoca Municipality, Romania","authors":"A. Kerekes, S. Poszet, A. Gál","doi":"10.21094/rg.2018.039","DOIUrl":"https://doi.org/10.21094/rg.2018.039","url":null,"abstract":"The administrative territory of Cluj–Napoca, due to its specific geological and geomorphological characteristics and anthropic activities, has been affected for a long time by landslides. Thus, it becomes necessary to analyse affected areas with different spatial methods, with the aim of generating landslide susceptibility maps. In this research, we studied the most prone area of the city, the Becaș stream watershed, situated in the Southern part of the municipality. The aim of this paper is to generate a valid susceptibility map, to be able to raise awareness about the existing situation: due to human induced activities and rapid urban growth, the peripheral part of Cluj–Napoca becomes more and more prone to mass–movements. We used the maximum entropy (MaxEnt) model, which was fed with accurate information on the existing landslides and seven landslide–causing factors: slope, aspect, land–use, depth of fragmentation, geology and plan– and profile curvature. The results confirm that the most influential factors are the land use and slope–angle, affected in a large degree by human activities. The accuracy of the generated map was verified using the AUC method, proving a very good performance (0.844) of the applied model.","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48286745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Evelpidou, Niki Polykreti, A. Karkani, Eirini Kardara, S. Seferli, Theofilos Valsamidis
Flash floods are one of the most significant natural hazards in the Mediterranean, affecting most basins in the region. Flash floods usually occur in ephemeral streams after particularly heavy rainfall. Although the average annual rainfall in the Cycladic islands (Greece) does not exceed 400 mm, flash floods are frequent, since most of that rainfall is often concentrated in few but very intense events. The case study is the drainage basin of Paratrechos or Peritsi stream in Naxos Island. This particular basin was selected due to the recorded flood events, the stream's proximity to the city that intensifies the flood impact, the slopes' gradient abrupt changes and the diverse infiltration rate of the geological formations. Furthermore, some parts of the basin are intact by human activities, while others are severely affected. This study investigates the relationship between rain and runoff through Unitary Hydrographs, in order to estimate and evaluate the flood potential of the aforementioned hydrologic basin and to determine the causes of the hazard and vulnerability. The Clark method was implemented and its results were further evaluated by field measurements.
{"title":"Modelling flood hazard at Paratrechos/Peritsi stream, Naxos Island (Cyclades, Greece)","authors":"N. Evelpidou, Niki Polykreti, A. Karkani, Eirini Kardara, S. Seferli, Theofilos Valsamidis","doi":"10.21094/rg.2018.035","DOIUrl":"https://doi.org/10.21094/rg.2018.035","url":null,"abstract":"Flash floods are one of the most significant natural hazards in the Mediterranean, affecting most basins in the region. Flash floods usually occur in ephemeral streams after particularly heavy rainfall. Although the average annual rainfall in the Cycladic islands (Greece) does not exceed 400 mm, flash floods are frequent, since most of that rainfall is often concentrated in few but very intense events. The case study is the drainage basin of Paratrechos or Peritsi stream in Naxos Island. This particular basin was selected due to the recorded flood events, the stream's proximity to the city that intensifies the flood impact, the slopes' gradient abrupt changes and the diverse infiltration rate of the geological formations. Furthermore, some parts of the basin are intact by human activities, while others are severely affected. This study investigates the relationship between rain and runoff through Unitary Hydrographs, in order to estimate and evaluate the flood potential of the aforementioned hydrologic basin and to determine the causes of the hazard and vulnerability. The Clark method was implemented and its results were further evaluated by field measurements.","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41444169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Gournelos, N. Evelpidou, A. Karkani, Eirini Kardara
There is a wide range of alternative approaches to study erosion processes. In this paper, we describe the construction of a model based on the interaction of Geographical Information System (GIS) and Artificial Neural Networks (ANN). The neural model uses supervised competitive learning process. The whole process begins with the digitization of collected data and the definition of the input variables, such as slope form and gradient, susceptibility to erosion and protective cover. The input variables are transformed into the erosion risk output variable using the neural model. The last stage is the development of a map of erosion risk zones. As a case study the island of Corfu (Ionian Sea, Greece) was chosen, which consists of lithologies very vulnerable to erosion and receives considerable amounts of rainfall, especially in comparison to the rest of Greece. Finally, the whole model was validated and its proper function was confirmed by field data observations.
{"title":"Recognition of erosion risk areas using Neural Network Technology: an application to the Island of Corfu","authors":"T. Gournelos, N. Evelpidou, A. Karkani, Eirini Kardara","doi":"10.21094/RG.2018.020","DOIUrl":"https://doi.org/10.21094/RG.2018.020","url":null,"abstract":"There is a wide range of alternative approaches to study erosion processes. In this paper, we describe the construction of a model based on the interaction of Geographical Information System (GIS) and Artificial Neural Networks (ANN). The neural model uses supervised competitive learning process. The whole process begins with the digitization of collected data and the definition of the input variables, such as slope form and gradient, susceptibility to erosion and protective cover. The input variables are transformed into the erosion risk output variable using the neural model. The last stage is the development of a map of erosion risk zones. As a case study the island of Corfu (Ionian Sea, Greece) was chosen, which consists of lithologies very vulnerable to erosion and receives considerable amounts of rainfall, especially in comparison to the rest of Greece. Finally, the whole model was validated and its proper function was confirmed by field data observations.","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43704211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The information contained by historical maps provides a good source of understanding the complex transformation of a deltaic environment by human activity. Using the Danube delta as an example, here we show that a artographic diagnosis for river deltas is based on four main steps that outline the learning stages for every similar area: 1) exploring coasts (for the early stages of the portolan and Ptolemaic maps); 2) exploring depths (for the succeeding imperial and military maps which focused on the access along the deltaic distributaries); 3) exploring deltaic networks (when economic and ecological reasons led to detailed topographic maps based on field measurements and aerial photos); 4) ecological protectionism (when ecological reasons dictate land use patterns and determine land use change). This synopsis is applicable to other river deltas with some adaptations imposed by the local context. We interpret the four stages in the description of the Delta as resting on and further reinforcing the power of the centre to dictate the uses of the periphery. We further argue that the way the territory is lived by local inhabitants is continuously marginalized and effaced. This stands in the way of future adaptive strategies.
{"title":"Simplifying a deltaic labyrinth: anthropogenic imprint on river deltas","authors":"Ş. Constantinescu, Mihnea Tănăsescu","doi":"10.21094/RG.2018.023","DOIUrl":"https://doi.org/10.21094/RG.2018.023","url":null,"abstract":"The information contained by historical maps provides a good source of understanding the complex transformation of a deltaic environment by human activity. Using the Danube delta as an example, here we show that a artographic diagnosis for river deltas is based on four main steps that outline the learning stages for every similar area: 1) exploring coasts (for the early stages of the portolan and Ptolemaic maps); 2) exploring depths (for the succeeding imperial and military maps which focused on the access along the deltaic distributaries); 3) exploring deltaic networks (when economic and ecological reasons led to detailed topographic maps based on field measurements and aerial photos); 4) ecological protectionism (when ecological reasons dictate land use patterns and determine land use change). This synopsis is applicable to other river deltas with some adaptations imposed by the local context. We interpret the four stages in the description of the Delta as resting on and further reinforcing the power of the centre to dictate the uses of the periphery. We further argue that the way the territory is lived by local inhabitants is continuously marginalized and effaced. This stands in the way of future adaptive strategies.","PeriodicalId":52661,"journal":{"name":"Revista de Geomorfologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48236154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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