Upper limits of flash flood stream power in Europe

Geomorphology ◽  
2016 ◽  
Vol 272 ◽  
pp. 68-77 ◽  
Author(s):  
Lorenzo Marchi ◽  
Marco Cavalli ◽  
William Amponsah ◽  
Marco Borga ◽  
Stefano Crema
Keyword(s):  
Flash Flood ◽  
Stream Power ◽  
Upper Limits

scholarly journals Estimation of flash flood hazard in the Pidima-Arfara area (Messinia, SW Greece), based on the study of instantaneous unitary hydrographs, longitudinal profilesand stream power

2007 ◽  
Vol 40 (4) ◽  
pp. 1621
Author(s):  
E. Sambaziotis ◽  
I. Fountoulis
Keyword(s):  
Flash Flood ◽  
Flood Hazard ◽  
Flash Floods ◽  
Topographic Map ◽  
Stream Power ◽  
Longitudinal Gradient ◽  
Hydrological Simulation ◽  
Small Catchment ◽  
Map Scale ◽  
Good Agreement

In this paper it is an effort to combine different methodologies in order to locate the sensitive sites in flash flood phenomena in a relatively small catchment located north of Kalamata (Messinia SW Péloponnèse, Greece). Based on digitised topographic map (scale 1/5.000) the longitudinal, gradient and stream power profiles of the watercourses were constructed and the results (possibly sensitive to flash floods sites) were compared to ones that came from applying hydrological simulation, hydrographs as well as Instantaneous Unitary Hydrographs. The comparison showed that the results were in good agreement.

scholarly journals Towards an increase of flash flood geomorphic effects due to gravel mining and ground subsidence in Nogalte stream (Murcia, SE Spain)

2016 ◽  
Vol 16 (10) ◽  
pp. 2273-2286 ◽  
Author(s):  
Jose Antonio Ortega-Becerril ◽  
Guillermina Garzón ◽  
Marta Béjar-Pizarro ◽  
Jose Jesús Martínez-Díaz
Keyword(s):  
Flash Flood ◽  
Time Lag ◽  
Alluvial Fan ◽  
Ground Subsidence ◽  
Flood Event ◽  
Stream Power ◽  
Base Level ◽  
Gravel Mining ◽  
Collateral Effects ◽  
Aquifer Overexploitation

Abstract. Transition from endorheic alluvial fan environments to well-channelized fluvial systems in natural conditions may occur in response to base-level fluctuations. However, human-induced changes in semi-arid regions can also be responsible for similar unforeseen modifications. Our results confirm that in-channel gravel mining and aquifer overexploitation over the last 50 years in the case study area have changed the natural stability of the Nogalte stream and, as a result, its geomorphic parameters including channel depth and longitudinal profile have begun to adapt to the new situation. Using interferometric synthetic aperture radar (InSAR) data we obtain maximum values for ground subsidence in the Upper Guadalentín Basin of  ∼ 10 cm yr−1 for the period 2003–2010. In this context of a lowered base level, the river is changing its natural flood model to a more powerful one. A comparison of the 1973 flood event, the most dramatic flood event ever recorded in the area, with the 2012 event, where there was a similar discharge but a sediment load deficit, reveals greater changes and a new flooding pattern and extension. In-channel gravel mining may be responsible for significant local changes in channel incision and profile. This, together with the collateral effects of aquifer overexploitation, can favour increased river velocity and stream power, which intensify the consequences of the flooding. The results obtained here clearly demonstrate an existing transition from the former alluvial pattern to a confined fluvial trend, which may become more pronounced in the future due to the time lag between the drop in aquifer level and ground subsidence, and introduce a new scenario to be taken into consideration in future natural hazard planning in this area.

scholarly journals Towards an increase of flash-flood geomorphic effects due to gravel mining and ground subsidence in Nogalte stream (SE Spain, Murcia)

2016 ◽  
Author(s):  
Jose A. Ortega-Becerril ◽  
Guillermina Garzón ◽  
Marta Béjar-Pizarro ◽  
Jose Jesús Martínez-Díaz
Keyword(s):  
Flash Flood ◽  
Time Lag ◽  
Alluvial Fan ◽  
Ground Subsidence ◽  
Stream Power ◽  
Fluvial Systems ◽  
Base Level ◽  
Gravel Mining ◽  
Collateral Effects ◽  
Aquifer Overexploitation

Abstract. Transition from endorheic alluvial fan environments to well-channelized fluvial systems in natural conditions may occur in response to base-level fluctuations. However, human-induced changes in semi-arid regions can also be responsible for similar unforeseen modifications. Our results confirm that in-channel gravel mining and aquifer overexploitation over the last 50 years in the case study area have changed the natural stability of the Nogalte stream and, as a result, its geomorphic parameters including channel depth and longitudinal profile have begun to adapt to the new situation. Using interferometric synthetic aperture radar (InSAR) data we obtain maximum values for ground subsidence in the Upper Guadalentín basin of ~ 10 cm yr−1 for the period 2003–2010. In this context of a lowered base level, the river is changing its natural flood model to a more energetic one. A comparison of the 1973 flood event, the most dramatic ever recorded in the area, with the 2012 event, where there was a similar discharge but a sediment load deficit, reveals greater changes and a new flooding pattern and extension. In-channel gravel mining may be responsible for significant local changes in channel incision and profile. This, together with the collateral effects of aquifer overexploitation, can favor increased river velocity and stream power, which intensify the consequences of the flooding. The results obtained here clearly demonstrate an existing transition from the former alluvial pattern to a confined fluvial trend, which may become more pronounced in the future due to the time-lag between the drop in aquifer level and ground subsidence, and introduce a new scenario to be taken into consideration in future natural hazard planning in this area.

scholarly journals Results of the post flash-flood disaster investigations in the Transylvanian Depression (Romania) during the last decade (2001–2010)

2013 ◽  
Vol 1 (6) ◽  
pp. 6199-6225
Author(s):  
V. Arghiuş ◽  
A. Ozunu ◽  
I. Samara ◽  
G. Roşian
Keyword(s):  
Flash Flood ◽  
Flash Floods ◽  
Flood Risk Management ◽  
Maximum Intensity ◽  
Stream Power ◽  
Negative Effects ◽  
Hydrological Data ◽  
Low Intensity ◽  
Management Measures ◽  
Peak Discharges

Abstract. Flash flood disasters are very rare in the Transylvanian Depression. In the last decades just three events were signalled in the study area, all of them during the last 10 yr. The flash floods occurring in the study area during the last decade had a significant impact on several localities situated at the Transylvanian Depression border. Based on the post flash flood investigation, the present study intends to find out the main characteristics of the flash-floods and the causes that have led to disasters in a region rarely affected by such kind of events. Analyzing the hydrological data, has been seen that the maximum intensity of the flash floods was observed in the upper and middle basins. By comparing the unit peak discharges from the studied region with other specific peak discharges related to the significant flash floods from Romania, it was noticed that the events from the Transylvanian Depression have moderate to low intensity. On the other hand, the results showed that beside high stream power and unexpected character common to flash floods, the inappropriate flood risk management measures increased the dimension of negative effects, leading to tens of life losses and economical damages of tens million dollars.

scholarly journals Hydrogeomorphic Impacts of Floods in a First-Order Catchment: Integrated Approach Based on Dendrogeomorphic Palaeostage Indicators, 2D Hydraulic Modelling and Sedimentological Parameters

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 212 ◽  
Author(s):  
Radek Tichavský ◽  
Stanislav Ruman ◽  
Tomáš Galia
Keyword(s):  
Peak Flow ◽  
Flash Flood ◽  
Integrated Approach ◽  
Hydraulic Modelling ◽  
Channel Stability ◽  
Stream Channels ◽  
Stream Power ◽  
First Order ◽  
Fine Sediments ◽  
Critical Unit

Floods represent frequent hazards in both low- and first-order catchments; however, to date, the investigation of peak flow discharges in the latter catchments has been omitted due to the absence of gauging stations. The quantification of flood parameters in a first-order catchment (1.8 km2) was realised in the moderate relief of NE Czechia, where the last flash flood event in 2014 caused considerable damage to the infrastructure. We used an integrated approach that included the dendrogeomorphic reconstruction of past flood activity, hydraulic modelling of the 2014 flash flood parameters using a two-dimensional IBER model, and evaluation of the channel stability using sedimentological parameters. Based on 115 flood scars, we identified 13 flood events during the period of 1955 to 2018, with the strongest signals recorded in 2014, 2009 and 1977. The modelled peak flow discharge of the last 2014 flood was equal to 4.5 m3·s−1 (RMSE = 0.32 m) using 26 scars as palaeostage indicators. The excess critical unit stream power was observed at only 24.2% of the reaches, representing predominantly bedrock and fine sediments. Despite local damage during the last flood, our results suggest relatively stable geomorphic conditions and gradual development of stream channels under discharges similar to that in 2014.

scholarly journals Recent human impacts and change in dynamics and morphology of ephemeral rivers

2013 ◽  
Vol 1 (2) ◽  
pp. 917-956 ◽  
Author(s):  
J. A. Ortega ◽  
L. Razola ◽  
G. Garzón
Keyword(s):  
Flash Flood ◽  
Human Impacts ◽  
Morphological Changes ◽  
Flood Event ◽  
Stream Power ◽  
Fluvial Systems ◽  
Before And After ◽  
Ephemeral Rivers ◽  
Natural Dynamics ◽  
Channel Patterns

Abstract. Ephemeral streams induce flash-flood events which cause dramatic morphological changes and impacts on population, due the intermittent activity of these fluvial systems. Human pressure changes the fluvial environment and so enhances the effects of natural dynamics. Local human-induced modifications can be latent over long periods of time. These changes can be studied after the flood event, to quantify their effects and detect which are most harmful. In this paper we study flash-flood effects at two sites in Spain and compare the results before and after a~flood event. Erosion is associated with areas where there have been more anthropogenic changes in floodplains and channels. Deposition is related to erosional processes in the watershed and to the tributaries. Disruption of river channel patterns changes connectivity and scouring appears due to energy excess. This excess tends to concentrate at weak points downstream produced by anthropic disturbances. Riparian vegetation is an energy sink and reaches with more cover show less erosion than those with deforestation. Infrastructures perpendicular to the direction of flow increase stream power, but peaks of erosion on the floodplain appear displaced downstream. It is important to detect human changes by analysis of hydraulic variables before the occurrence of an extraordinary event in order to anticipate catastrophic consequences resulting from inappropriate fluvial management.

scholarly journals Results of the post flash-flood disaster investigations in the Transylvanian Depression (Romania) during the last decade (2001–2010)

2014 ◽  
Vol 14 (3) ◽  
pp. 535-544 ◽  
Author(s):  
V. Arghiuş ◽  
A. Ozunu ◽  
I. Samara ◽  
G. Roşian
Keyword(s):  
Flash Flood ◽  
Flash Floods ◽  
Flood Risk Management ◽  
Maximum Intensity ◽  
Stream Power ◽  
Negative Effects ◽  
Hydrological Data ◽  
Low Intensity ◽  
Management Measures ◽  
Peak Discharges

Abstract. Flash-flood disasters are very rare in the Transylvanian Depression. In the last decades just three events were signalled in the study area, all of them during the last 10 years. The flash floods occurring in the study area during the last decade had a significant impact on several localities situated at the Transylvanian Depression border. Based on the post flash-flood investigation, the present study intends to find out the main characteristics of the flash floods and the causes that have led to disasters in a region rarely affected by such kinds of events. Analyzing the hydrological data, it has been seen that the maximum intensity of the flash floods was observed in the upper and middle basins. By comparing the unit peak discharges from the studied region with other specific peak discharges related to the significant flash floods from Romania, it was noticed that the events from the Transylvanian Depression have moderate to low intensity. On the other hand, the results showed that besides high stream power and unexpected character common to flash floods, the inappropriate flood risk management measures increased the dimension of the negative effects, leading to tens of lives lost and economical damages of tens of millions of dollars.

scholarly journals PERFORMANCE OF MACHINE LEARNING ALGORITHMS FOR MAPPING AND FORECASTING OF FLASH FLOOD SUSCEPTIBILITY IN TETOUAN, MOROCCO

2022 ◽  
Vol XLVI-4/W3-2021 ◽  
pp. 305-313
Author(s):  
E. M. Sellami ◽  
M. Maanan ◽  
H. Rhinane
Keyword(s):  
Industrial Revolution ◽  
Flash Flood ◽  
Machine Learning Algorithms ◽  
Slope Aspect ◽  
Support Vector ◽  
Kappa Statistics ◽  
Kappa Index ◽  
Stream Power ◽  
Topographic Wetness Index ◽  
Flood Susceptibility

Abstract. Since the industrial revolution, the world is experiencing a huge change in its climate, which causes many imbalances such as flash floods (FF). The aim of this study is to propose a new approach for detection and forecasting of flash flood susceptibility in the city of Tetouan, Morocco. For this regard, support vector machine (SVM), logistic regression (LR), random forest (RF), Naïve Bayes (NB) and Artificial neural network (ANN) are used based on 1101 points (680 flood points and 421 non-flood points) and 9 flash-flood predictors (Elevation , Slope , Aspect , LU/LC , Stream Power Index , Plan curvature , Profile Curvature , Topographic Position Index and Topographic Wetness Index ) that were extracted from the DEM (10m resolution) and satellite imagery (Sentinel 2B) of the study area . Models were trained on 70% and tested on 30% of this dataset also they were evaluated using several metrics such as the Receiver Operating Characteristic (ROC) Curve, precision, recall, score and kappa index. The result demonstrated that RF (AUC = 0.99, Accuracy = 96%, Kappa statistics = 0.92) has the highest performance, followed by ANN (AUC = 0.98, Accuracy = 95%, Kappa statistics = 0.89) and SVM (AUC = 0.96, Accuracy = 92%, Kappa statistics = 0.80). The proposed approach is an effective tool for forecasting and predicting FF that can help reduce the severity of this disaster.

Vitamin-A-Exzess durch Pferdefleischprodukte mit hohen Leberanteilen

2013 ◽  
Vol 41 (01) ◽  
pp. 31-36
Author(s):  
E. Kienzle ◽  
N. Becker
Keyword(s):  
Vitamin A ◽  
Eine Analyse ◽  
Upper Limit ◽  
Upper Limits

ZusammenfassungIm Rahmen einer Eliminationsdiät wird regelmäßig Pferdefleisch eingesetzt. Aus Gründen der Praktikabilität verwenden Tierbesitzer häufig kommerziell erhältliches Pferdefleisch aus der Dose. Aufgrund eines Berichts von Zervikalspondylosen bei einer auf Futtermittel allergischen Katze erfolgte eine Analyse verschiedener auf Pferdefleisch basierender Produkte hinsichtlich des Vitamin-AGehalts.In 14 Pferdefleischerzeugnissen wurde der Vitamin-A-Gehalt (Retinol) analysiert. Der Gehalt an umsetzbarer Energie wurde mithilfe von Schätzformeln auf Basis der Deklaration berechnet.In Produkten mit deklarierten Anteilen von Leber, Innereien oder tierischen Nebenprodukten konnten zum Teil erhebliche Vitamin-A-Gehalte festgestellt werden. Bei alleiniger Verfütterung eines dieser Produkte (Deckung des durchschnittlichen Energiebedarfs) würde die Vitamin-A-Versorgung nur knapp unter dem Safe Upper Limit der Katze sowie oberhalb des Safe Upper Limits beim Hund liegen.Bei All-Meat-Produkten sollte nicht nur die Deklaration, sondern auch der Inhalt näher betrachtet werden, um einen Hinweis auf eventuell hohe Leberanteile zu erhalten.Aufgrund der Ergebnisse ist eine exzessive Vitamin-A-Aufnahme bei langfristiger Verfütterung von Pferdefleischprodukten mit hohen Leberanteilen nicht auszuschließen.

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